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37 pages, 10299 KiB

Open AccessArticle

Microporous Activated Carbon from Pisum sativum Pods Using Various Activation Methods and Tested for Adsorption of Acid Orange 7 Dye from Water

by Mohamed A. El-Nemr, Ahmed El Nemr, Mohamed A. Hassaan, Safaa Ragab, Luigi Tedone, Giuseppe De Mastro and Antonio Pantaleo

Molecules 2022, 27(15), 4840; https://doi.org/10.3390/molecules27154840 - 28 Jul 2022

Cited by 35 | Viewed by 3168

Abstract

This work demonstrates the preparation of high-surface-area activated carbon (AC) from Pisum sativum pods using ZnCl₂ and KOH as activating agents. The influence of CO₂ and N₂ gases during the carbonization process on the porosity of AC were studied. The [...] Read more.

This work demonstrates the preparation of high-surface-area activated carbon (AC) from Pisum sativum pods using ZnCl₂ and KOH as activating agents. The influence of CO₂ and N₂ gases during the carbonization process on the porosity of AC were studied. The highest specific surface area of AC was estimated at 1300 to 1500 m²/g, which presented characteristics of microporous materials. SEM micrographs revealed that chemical activation using an impregnation reagent ZnCl₂ increases the porosity of the AC, which in turn leads to an increase in the surface area, and the SEM image showed that particle size diameter ranged between 48.88 and 69.95 nm. The performance of prepared AC for adsorption of Acid Orange 7 (AO7) dye was tested. The results showed that the adsorption percentage by AC (2.5 g/L) was equal to 94.76% after just 15 min, and the percentage of removal increased to be ~100% after 60 min. The maximum adsorption capacity was 473.93 mg g⁻¹. A Langmuir model (LM) shows the best-fitted equilibrium isotherm, and the kinetic data fitted better to the pseudo-second-order and Film diffusion models. The removal of AO7 dye using AC from Pisum sativum pods was optimized using a response factor model (RSM), and the results were reported. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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16 pages, 7676 KiB

Open AccessArticle

Nano-Silica Modified with Diamine for Capturing Azo Dye from Aqueous Solutions

by Enshirah Da’na

Molecules 2022, 27(11), 3366; https://doi.org/10.3390/molecules27113366 - 24 May 2022

Cited by 7 | Viewed by 1773

Abstract

Nano-silica particles decorated with amine groups (S-DA) were prepared via a simple, one-pot method, and under very mild conditions in an attempt to improve the affinity of the silica nanoparticles toward capturing anionic organic dye, namely, methyl orange (MO). The prepared sample was [...] Read more.

Nano-silica particles decorated with amine groups (S-DA) were prepared via a simple, one-pot method, and under very mild conditions in an attempt to improve the affinity of the silica nanoparticles toward capturing anionic organic dye, namely, methyl orange (MO). The prepared sample was characterized by different techniques such as XRD for crystallinity, SEM for morphological structure, TGA for thermal stability, BET surface area, and FTIR for surface functional groups. The prepared sample was tested for the removal of MO under different conditions including the mass of adsorbent, pH, initial concentration, and time. Results showed that the adsorption of MO was very fast with equilibrium achieved in less than 30 min and a maximum removal efficiency of 100% for a mass to volume ratio of 10 g/3 L, a pH of 2.5, initial concentration of 10 mgL⁻¹, and under stagnant conditions. These results were compared with a bare nano-silica, which was not able to adsorb more than 3% after 24 h, indicating the important effect of amine groups. Furthermore, recycling the adsorbent was achieved by rinsing the MO-loaded adsorbent with a dilute solution of KOH. The adsorbent maintained 50% of its initial removal efficiency after four adsorption–desorption cycles. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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14 pages, 3533 KiB

Open AccessArticle

Coffee Beverage: A New Strategy for the Synthesis of Polymethacrylates via ATRP

by Karolina Surmacz, Paweł Błoniarz and Paweł Chmielarz

Molecules 2022, 27(3), 840; https://doi.org/10.3390/molecules27030840 - 27 Jan 2022

Cited by 13 | Viewed by 3292

Abstract

Coffee, the most popular beverage in the 21st century society, was tested as a reaction environment for activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) without an additional reducing agent. Two blends were selected: pure Arabica beans and a proportional [...] Read more.

Coffee, the most popular beverage in the 21st century society, was tested as a reaction environment for activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) without an additional reducing agent. Two blends were selected: pure Arabica beans and a proportional blend of Arabica and Robusta beans. The use of the solution received from the mixture with Robusta obtained a high molecular weight polymer product in a short time while maintaining a controlled structure of the synthesized product. Various monomers with hydrophilic characteristics, i.e., 2-(dimethylamino)ethyl methacrylate (DMAEMA), oligo(ethylene glycol) methyl ether methacrylate (OEGMA₅₀₀), and glycidyl methacrylate (GMA), were polymerized. The proposed concept was carried out at different concentrations of coffee grounds, followed by the determination of the molar concentration of caffeine in applied beverages using DPV and HPLC techniques. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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12 pages, 2186 KiB

Open AccessArticle

Antimicrobial Efficacy of Glass Ionomer Cement in Incorporation with Biogenic Zingiber officinale Capped Silver-Nanobiotic, Chlorhexidine Diacetate and Lyophilized Miswak

by Amal Adnan Ashour, Sakeenabi Basha, Nayef H. Felemban, Enas T. Enan, Amal Ahmed Alyamani and Sanaa M. F. Gad El-Rab

Molecules 2022, 27(2), 528; https://doi.org/10.3390/molecules27020528 - 14 Jan 2022

Cited by 13 | Viewed by 2486

Abstract

In the present study, Zingiber officinale is used for the synthesis of Zingiber officinale capped silver nanoparticles (ZOE-AgNPs) and compares the antimicrobial efficacy and compressive strength of conventional glass ionomer cement (GIC) combined with ZOE-AgNPs, lyophilized miswak, and chlorhexidine diacetate (CHX) against oral [...] Read more.

In the present study, Zingiber officinale is used for the synthesis of Zingiber officinale capped silver nanoparticles (ZOE-AgNPs) and compares the antimicrobial efficacy and compressive strength of conventional glass ionomer cement (GIC) combined with ZOE-AgNPs, lyophilized miswak, and chlorhexidine diacetate (CHX) against oral microbes. Five groups of the disc-shaped GIC specimens were prepared. Group A: lyophilized miswak and GIC combination, Group B: ZOE-AgNPs and GIC combinations, Group C: CHX and GIC combination, Group D: ZOE-AgNPs + CHX + GIC; Group E: Conventional GIC. Results confirmed the successful formation of ZOE-AgNPs that was monitored by UV-Vis sharp absorption spectra at 415 nm. The X-ray diffractometer (XRD) and transmission electron microscope (TEM) results revealed the formation of ZOE-AgNPs with a mean size 10.5–14.12 nm. The peaks of the Fourier transform infrared spectroscopy (FTIR) were appearing the involvement of ZOE components onto the surface of ZOE-AgNPs which played as bioreducing, and stabilizing agents. At a 24-h, one-week and three-week intervals, Group D showed the significantly highest mean inhibitory zones compared to Group A, Group B, and Group C. At microbe-level comparison, Streptococcus mutans and Staphylococcus aureus were inhibited significantly by all the specimens tested except group E when compared to Candida albicans. Group D specimens showed slightly higher (45.8 ± 5.4) mean compressive strength in comparison with other groups. The combination of GIC with ZOE-AgNPs and chlorhexidine together enhanced its antimicrobial efficacy and compressive strength compared to GIC with ZOE-AgNPs or lyophilized miswak or chlorhexidine combination alone. The present study revealed that The combination of GIC with active components of ZOE-AgNPs and chlorhexidine paves the way to lead its effective nano-dental materials applications. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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12 pages, 4139 KiB

Open AccessArticle

Monolayer and Bilayer Formation of Molecular 2D Networks Assembled at the Liquid/Solid Interfaces by Solution-Based Drop-Cast Method

by Xingming Zeng, Yi Hu, Rongbin Xie, Sadaf Bashir Khan and Shern-Long Lee

Molecules 2021, 26(24), 7707; https://doi.org/10.3390/molecules26247707 - 20 Dec 2021

Cited by 5 | Viewed by 3265

Abstract

In recent years, extending self-assembled structures from two-dimensions (2D) to three-dimensions (3D) has been a paradigm in surface supramolecular chemistry and contemporary nanotechnology. Using organic molecules of p-terphenyl-3,5,3′,5′-tetracarboxylic acid (TPTC), and scanning tunneling microscopy (STM), we present a simple route, that is the [...] Read more.

In recent years, extending self-assembled structures from two-dimensions (2D) to three-dimensions (3D) has been a paradigm in surface supramolecular chemistry and contemporary nanotechnology. Using organic molecules of p-terphenyl-3,5,3′,5′-tetracarboxylic acid (TPTC), and scanning tunneling microscopy (STM), we present a simple route, that is the control of the solute solubility in a sample solution, to achieve the vertical growth of supramolecular self-assemblies, which would otherwise form monolayers at the organic solvent/graphite interface. Presumably, the bilayer formations were based on π-conjugated overlapped molecular dimers that worked as nuclei to induce the yielding of the second layer. We also tested other molecules, including trimesic acid (TMA) and 1,3,5-tris(4-carboxyphenyl)-benzene (BTB), as well as the further application of our methodology, demonstrating the facile preparation of layered assemblies. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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18 pages, 3552 KiB

Open AccessArticle

Carbon Nanotubes Hybrid Hydrogels for Environmental Remediation: Evaluation of Adsorption Efficiency under Electric Field

by Giuseppe Cirillo, Manuela Curcio, Lorenzo Francesco Madeo, Francesca Iemma, Giovanni De Filpo, Silke Hampel and Fiore Pasquale Nicoletta

Molecules 2021, 26(22), 7001; https://doi.org/10.3390/molecules26227001 - 19 Nov 2021

Cited by 6 | Viewed by 1937

Abstract

The performance of Carbon Nanotubes hybrid hydrogels for environmental remediation was investigated using Methylene Blue (MB), Rhodamine B (RD), and Bengal Rose (BR) as model contaminating dyes. An acrylate hydrogel network with incorporated CNT was synthesized by photo-polymerization without any preliminary derivatization of [...] Read more.

The performance of Carbon Nanotubes hybrid hydrogels for environmental remediation was investigated using Methylene Blue (MB), Rhodamine B (RD), and Bengal Rose (BR) as model contaminating dyes. An acrylate hydrogel network with incorporated CNT was synthesized by photo-polymerization without any preliminary derivatization of CNT surface. Thermodynamics, isothermal and kinetic studies showed favorable sorption processes with the application of an external 12 V electric field found to be able to influence the amount of adsorbed dyes: stronger interactions with cationic MB molecules (

q_{e x p}

and

q_{e x p}^{12}

of 19.72 and 33.45 mg g⁻¹, respectively) and reduced affinity for anionic RD (

q_{e x p}

and

q_{e x p}^{12}

of 28.93 and 13.06 mg g⁻¹, respectively) and neutral BR (

q_{e x p}

and

q_{e x p}^{12}

of 36.75 and 15.85 mg g⁻¹, respectively) molecules were recorded. The influence of pH variation on dyes adsorption was finally highlighted by reusability studies, with the negligible variation of adsorption capacity after five repeated sorption cycles claiming for the suitability of the proposed systems as effective sorbent for wastewater treatment. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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16 pages, 4971 KiB

Open AccessArticle

Phosphate and Ammonium Removal from Wastewaters Using Natural-Based Innovative Bentonites Impacting on Resource Recovery and Circular Economy

by Miltiadis Zamparas, Grigorios L. Kyriakopoulos, Marios Drosos and Vasilis C. Kapsalis

Molecules 2021, 26(21), 6684; https://doi.org/10.3390/molecules26216684 - 4 Nov 2021

Cited by 12 | Viewed by 2096

Abstract

The research objective of the study is the estimation of a novel low-cost composite material f-MB (Fe-modified bentonite) as a P and N adsorbent from wastewaters. Τhe present study aimed at examining the phosphate and ammonium removal efficiency from different types of [...] Read more.

The research objective of the study is the estimation of a novel low-cost composite material f-MB (Fe-modified bentonite) as a P and N adsorbent from wastewaters. Τhe present study aimed at examining the phosphate and ammonium removal efficiency from different types of wastewater using f-MB, by conducting bench-scale batch experiments to investigate its equilibrium characteristics and kinetics. The SEM analysis revealed that the platelets of bentonite in f-MB do not form normal bentonite sheets, but they have been restructured in a more compact formation with a great porosity. Regarding the sorption efficiencies (Qm), the maximum phosphate sorption efficiencies (Qm) calculated using the Langmuir model were 24.54, 25.09, 26.13, 24.28, and 23.21 mg/g, respectively, for a pH range of 5 to 9. In addition, the maximum NH₄⁺-N adsorption capacities (Qm) calculated from the Langmuir model were 131.8, 145.7, 168.5, 156.7, and 159.6 mg/g, respectively, for a pH range from 5 to 9. Another important finding of this study is that f-MB can recover P from treated wastewater impacting on resource recovery and circular economy (CE). The modified clay f-MB performed the phosphate and ammonium recovery rates of 80% and 78.5%, respectively. Finally, f-MB can slowly release the largest proportion of phosphate and ammonium ions for a long time, thus extending the application of the f-MB material as a slow-release fertilizer and soil improver. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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14 pages, 10160 KiB

Open AccessArticle

Innovative Development of Batch Dyed 3D Printed Acrylonitrile/Butadiene/Styrene Objects

by Suzana Kutnjak-Mravlinčić, Ana Sutlović, Martinia Ira Glogar, Sanja Ercegović Ražić and Damir Godec

Molecules 2021, 26(21), 6637; https://doi.org/10.3390/molecules26216637 - 2 Nov 2021

Cited by 2 | Viewed by 2847

Abstract

According to the great impact of additive technology on the development of modern industry, a lot of research is being done to obtain 3D printed parts with better properties. This research is extremely important because there are no scientific papers in the field [...] Read more.

According to the great impact of additive technology on the development of modern industry, a lot of research is being done to obtain 3D printed parts with better properties. This research is extremely important because there are no scientific papers in the field of post dyeing of acrylonitrile/butadiene/styrene (ABS) 3D printed parts. The experiment was carried out using disperse dyes on ABS specimens. The obtained coloration of the specimens was in the primary colors (yellow, red, and blue) in the specified dyestuff concentration range and was evaluated using an objective CIELab system. Based on the obtained color parameters, remission values and Kubelka-Munk coefficient, dye mixtures and an ombre effect were performed to obtain patterns in the desired hues. Abrasion resistance of disperse dyed specimens was tested using different abrasive materials over a wide range of fineness to simulate different indoor and outdoor soils and was compared to abrasion resistance of specimens produced from the industrially dyed wire with the master batch. The results show that 3D printed ABS products can be produced in one or more desired shades with satisfactory abrasion resistance. This undoubtedly represents the added value of 3D printed ABS parts and extends their application to the field of creative industries and design, specifically footwear design. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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16 pages, 2268 KiB

Open AccessArticle

Concentration-Dependent Multi-Potentiality of L-Arginine: Antimicrobial Effect, Hydroxyapatite Stability, and MMPs Inhibition

by Mohammed Nadeem Bijle, Mallikarjuna Rao Pichika, Kit-Kay Mak, Abhishek Parolia, Muneer Gohar Babar, Cynthia Yiu and Umer Daood

Molecules 2021, 26(21), 6605; https://doi.org/10.3390/molecules26216605 - 31 Oct 2021

Cited by 7 | Viewed by 2625

Abstract

This study’s objective was to examine L-arginine (L-arg) supplementation’s effect on mono-species biofilm (Streptococcus mutans/Streptococcus sanguinis) growth and underlying enamel substrates. The experimental groups were 1%, 2%, and 4% arg, and 0.9% NaCl was used as the vehicle control. [...] Read more.

This study’s objective was to examine L-arginine (L-arg) supplementation’s effect on mono-species biofilm (Streptococcus mutans/Streptococcus sanguinis) growth and underlying enamel substrates. The experimental groups were 1%, 2%, and 4% arg, and 0.9% NaCl was used as the vehicle control. Sterilised enamel blocks were subjected to 7-day treatment with test solutions and S. mutans/S. sanguinis inoculum in BHI. Post-treatment, the treated biofilms stained for live/dead bacterial cells were analysed using confocal microscopy. The enamel specimens were analysed using X-ray diffraction crystallography (XRD), Raman spectroscopy (RS), and transmission electron microscopy (TEM). The molecular interactions between arg and MMP-2/MMP-9 were determined by computational molecular docking and MMP assays. With increasing arg concentrations, bacterial survival significantly decreased (p < 0.05). The XRD peak intensity with 1%/2% arg was significantly higher than with 4% arg and the control (p < 0.05). The bands associated with the mineral phase by RS were significantly accentuated in the 1%/2% arg specimens compared to in other groups (p < 0.05). The TEM analysis revealed that 4% arg exhibited an ill-defined shape of enamel crystals. Docking of arg molecules to MMPs appears feasible, with arg inhibiting MMP-2/MMP-9 (p < 0.05). L-arginine supplementation has an antimicrobial effect on mono-species biofilm. L-arginine treatment at lower (1%/2%) concentrations exhibits enamel hydroxyapatite stability, while the molecule has the potential to inhibit MMP-2/MMP-9. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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17 pages, 4461 KiB

Open AccessArticle

Significantly Improved Colossal Dielectric Properties and Maxwell—Wagner Relaxation of TiO₂—Rich Na_1/2Y_1/2Cu₃Ti_4+xO₁₂ Ceramics

by Pariwat Saengvong, Narong Chanlek, Bundit Putasaeng, Atip Pengpad, Viyada Harnchana, Sriprajak Krongsuk, Pornjuk Srepusharawoot and Prasit Thongbai

Molecules 2021, 26(19), 6043; https://doi.org/10.3390/molecules26196043 - 5 Oct 2021

Cited by 13 | Viewed by 1781

Abstract

In this work, the colossal dielectric properties and Maxwell—Wagner relaxation of TiO₂–rich Na_1/2Y_1/2Cu₃Ti_4+xO₁₂ (x = 0–0.2) ceramics prepared by a solid-state reaction method are investigated. A single phase of Na [...] Read more.

In this work, the colossal dielectric properties and Maxwell—Wagner relaxation of TiO₂–rich Na_1/2Y_1/2Cu₃Ti_4+xO₁₂ (x = 0–0.2) ceramics prepared by a solid-state reaction method are investigated. A single phase of Na_1/2Y_1/2Cu₃Ti₄O₁₂ is achieved without the detection of any impurity phase. The highly dense microstructure is obtained, and the mean grain size is significantly reduced by a factor of 10 by increasing Ti molar ratio, resulting in an increased grain boundary density and hence grain boundary resistance (R_gb). The colossal permittivities of ε′ ~ 0.7–1.4 × 10⁴ with slightly dependent on frequency in the frequency range of 10²–10⁶ Hz are obtained in the TiO₂–rich Na_1/2Y_1/2Cu₃Ti_4+xO₁₂ ceramics, while the dielectric loss tangent is reduced to tanδ ~ 0.016–0.020 at 1 kHz due to the increased R_gb. The semiconducting grain resistance (R_g) of the Na_1/2Y_1/2Cu₃Ti_4+xO₁₂ ceramics increases with increasing x, corresponding to the decrease in Cu⁺/Cu²⁺ ratio. The nonlinear electrical properties of the TiO₂–rich Na_1/2Y_1/2Cu₃Ti_4+xO₁₂ ceramics can also be improved. The colossal dielectric and nonlinear electrical properties of the TiO₂–rich Na_1/2Y_1/2Cu₃Ti_4+xO₁₂ ceramics are explained by the Maxwell–Wagner relaxation model based on the formation of the Schottky barrier at the grain boundary. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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16 pages, 1860 KiB

Open AccessArticle

Effects of Temperature on Enantiomerization Energy and Distribution of Isomers in the Chiral Cu₁₃ Cluster

by Cesar Castillo-Quevedo, Carlos Emiliano Buelna-Garcia, Edgar Paredes-Sotelo, Eduardo Robles-Chaparro, Edgar Zamora-Gonzalez, Martha Fabiola Martin-del-Campo-Solis, Jesus Manuel Quiroz-Castillo, Teresa del-Castillo-Castro, Gerardo Martínez-Guajardo, Aned de-Leon-Flores, Manuel Cortez-Valadez, Filiberto Ortiz-Chi, Tulio Gaxiola, Santos Jesus Castillo, Alejandro Vásquez-Espinal, Sudip Pan and Jose Luis Cabellos

Molecules 2021, 26(18), 5710; https://doi.org/10.3390/molecules26185710 - 21 Sep 2021

Cited by 8 | Viewed by 3663

Abstract

In this study, we report the lowest energy structure of bare Cu₁₃ nanoclusters as a pair of enantiomers at room temperature. Moreover, we compute the enantiomerization energy for the interconversion from minus to plus structures in the chiral putative global minimum for [...] Read more.

In this study, we report the lowest energy structure of bare Cu₁₃ nanoclusters as a pair of enantiomers at room temperature. Moreover, we compute the enantiomerization energy for the interconversion from minus to plus structures in the chiral putative global minimum for temperatures ranging from 20 to 1300 K. Additionally, employing nanothermodynamics, we compute the probabilities of occurrence for each particular isomer as a function of temperature. To achieve that, we explore the free energy surface of the Cu₁₃ cluster, employing a genetic algorithm coupled with density functional theory. Moreover, we discuss the energetic ordering of isomers computed with various density functionals. Based on the computed thermal population, our results show that the chiral putative global minimum strongly dominates at room temperature. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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13 pages, 2670 KiB

Open AccessFeature PaperArticle

Systematic Exploration of the Synthetic Parameters for the Production of Dynamic VO₂(M1)

by Giulia Bragaggia, Andrea Cacciatore, Elisa Poffe, Claudia Capone, Federico Zorzi, Valerio Causin and Silvia Gross

Molecules 2021, 26(15), 4513; https://doi.org/10.3390/molecules26154513 - 27 Jul 2021

Cited by 7 | Viewed by 2112

Abstract

Thermochromic dynamic cool materials present a reversible change of their properties wherein by increasing the temperature, the reflectance, conductivity, and transmittance change due to a reversible crystalline phase transition. In particular, vanadium (IV) dioxide shows a reversible phase transition, accompanied by a change [...] Read more.

Thermochromic dynamic cool materials present a reversible change of their properties wherein by increasing the temperature, the reflectance, conductivity, and transmittance change due to a reversible crystalline phase transition. In particular, vanadium (IV) dioxide shows a reversible phase transition, accompanied by a change in optical properties, from monoclinic VO₂(M1) to tetragonal VO₂(R). In this paper, we report on a systematic exploration of the parameters for the synthesis of vanadium dioxide VO₂(M1) via an easy, sustainable, reproducible, fast, scalable, and low-cost hydrothermal route without hazardous chemicals, followed by an annealing treatment. The metastable phase VO₂(B), obtained via a hydrothermal route, was converted into the stable VO₂(M1), which shows a metal–insulator transition (MIT) at 68 °C that is useful for different applications, from energy-efficient smart windows to dynamic concrete. Within this scenario, a further functionalization of the oxide nanostructures with tetraethyl orthosilicate (TEOS), characterized by an extreme alkaline environment, was carried out to ensure compatibility with the concrete matrix. Structural properties of the synthesized vanadium dioxides were investigated using temperature-dependent X-ray Diffraction analysis (XRD), while compositional and morphological properties were assessed using Scanning Electron Microscopy, Energy Dispersive X-ray Analysis (SEM-EDX), and Transmission Electron Microscopy (TEM). Differential Scanning Calorimetry (DSC) analysis was used to investigate the thermal behavior. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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23 pages, 3572 KiB

Open AccessArticle

Theoretical Prediction of Structures, Vibrational Circular Dichroism, and Infrared Spectra of Chiral Be₄B₈ Cluster at Different Temperatures

by Carlos Emiliano Buelna-García, Eduardo Robles-Chaparro, Tristan Parra-Arellano, Jesus Manuel Quiroz-Castillo, Teresa del-Castillo-Castro, Gerardo Martínez-Guajardo, Cesar Castillo-Quevedo, Aned de-León-Flores, Gilberto Anzueto-Sánchez, Martha Fabiola Martin-del-Campo-Solis, Ana Maria Mendoza-Wilson, Alejandro Vásquez-Espinal and Jose Luis Cabellos

Molecules 2021, 26(13), 3953; https://doi.org/10.3390/molecules26133953 - 28 Jun 2021

Cited by 12 | Viewed by 4212

Abstract

Lowest-energy structures, the distribution of isomers, and their molecular properties depend significantly on geometry and temperature. Total energy computations using DFT methodology are typically carried out at a temperature of zero K; thereby, entropic contributions to the total energy are neglected, even though [...] Read more.

Lowest-energy structures, the distribution of isomers, and their molecular properties depend significantly on geometry and temperature. Total energy computations using DFT methodology are typically carried out at a temperature of zero K; thereby, entropic contributions to the total energy are neglected, even though functional materials work at finite temperatures. In the present study, the probability of the occurrence of one particular Be₄B₈ isomer at temperature T is estimated by employing Gibbs free energy computed within the framework of quantum statistical mechanics and nanothermodynamics. To identify a list of all possible low-energy chiral and achiral structures, an exhaustive and efficient exploration of the potential/free energy surfaces is carried out using a multi-level multistep global genetic algorithm search coupled with DFT. In addition, we discuss the energetic ordering of structures computed at the DFT level against single-point energy calculations at the CCSD(T) level of theory. The total VCD/IR spectra as a function of temperature are computed using each isomer’s probability of occurrence in a Boltzmann-weighted superposition of each isomer’s spectrum. Additionally, we present chemical bonding analysis using the adaptive natural density partitioning method in the chiral putative global minimum. The transition state structures and the enantiomer–enantiomer and enantiomer–achiral activation energies as a function of temperature evidence that a change from an endergonic to an exergonic type of reaction occurs at a temperature of 739 K. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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19 pages, 5552 KiB

Open AccessArticle

Thermal Charging Optimization of a Wavy-Shaped Nano-Enhanced Thermal Storage Unit

by Mohammad Ghalambaz, S.A.M. Mehryan, Ahmad Hajjar, Mohammad Yacoub Al Shdaifat, Obai Younis, Pouyan Talebizadehsardari and Wahiba Yaïci

Molecules 2021, 26(5), 1496; https://doi.org/10.3390/molecules26051496 - 9 Mar 2021

Cited by 5 | Viewed by 2320

Abstract

A wavy shape was used to enhance the thermal heat transfer in a shell-tube latent heat thermal energy storage (LHTES) unit. The thermal storage unit was filled with CuO–coconut oil nano-enhanced phase change material (NePCM). The enthalpy-porosity approach was employed to model the [...] Read more.

A wavy shape was used to enhance the thermal heat transfer in a shell-tube latent heat thermal energy storage (LHTES) unit. The thermal storage unit was filled with CuO–coconut oil nano-enhanced phase change material (NePCM). The enthalpy-porosity approach was employed to model the phase change heat transfer in the presence of natural convection effects in the molten NePCM. The finite element method was applied to integrate the governing equations for fluid motion and phase change heat transfer. The impact of wave amplitude and wave number of the heated tube, as well as the volume concertation of nanoparticles on the full-charging time of the LHTES unit, was addressed. The Taguchi optimization method was used to find an optimum design of the LHTES unit. The results showed that an increase in the volume fraction of nanoparticles reduces the charging time. Moreover, the waviness of the tube resists the natural convection flow circulation in the phase change domain and could increase the charging time. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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17 pages, 2122 KiB

Open AccessArticle

Effect of Propolis Nanoparticles against Enterococcus faecalis Biofilm in the Root Canal

by Abhishek Parolia, Haresh Kumar, Srinivasan Ramamurthy, Thiagarajan Madheswaran, Fabian Davamani, Malikarjuna Rao Pichika, Kit-Kay Mak, Amr S Fawzy, Umer Daood and Allan Pau

Molecules 2021, 26(3), 715; https://doi.org/10.3390/molecules26030715 - 30 Jan 2021

Cited by 29 | Viewed by 4958

Abstract

To determine the antibacterial effect of propolis nanoparticles (PNs) as an endodontic irrigant against Enterococcus faecalis biofilm inside the endodontic root canal system. Two-hundred-ten extracted human teeth were sectioned to obtain 6 mm of the middle third of the root. The root canal [...] Read more.

To determine the antibacterial effect of propolis nanoparticles (PNs) as an endodontic irrigant against Enterococcus faecalis biofilm inside the endodontic root canal system. Two-hundred-ten extracted human teeth were sectioned to obtain 6 mm of the middle third of the root. The root canal was enlarged to an internal diameter of 0.9 mm. The specimens were inoculated with E. faecalis for 21 days. Following this, specimens were randomly divided into seven groups, with 30 dentinal blocks in each group including: group I—saline; group II—propolis 100 µg/mL; group III—propolis 300 µg/mL; group IV—propolis nanoparticle 100 µg/mL; group V—propolis nanoparticle 300µg/mL; group VI—6% sodium hypochlorite; group VII—2% chlorhexidine. Dentin shavings were collected at 200 and 400 μm depths, and total numbers of CFUs were determined at the end of one, five, and ten minutes. The non-parametric Kruskal–Wallis and Mann–Whitney tests were used to compare the differences in reduction in CFUs between all groups, and probability values of p < 0.05 were set as the reference for statistically significant results. The antibacterial effect of PNs as an endodontic irrigant was also assessed against E. faecalis isolates from patients with failed root canal treatment. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were also performed after exposure to PNs. A Raman spectroscope, equipped with a Leica microscope and lenses with curve-fitting Raman software, was used for analysis. The molecular interactions between bioactive compounds of propolis (Pinocembrin, Kaempferol, and Quercetin) and the proteins Sortase A and β-galactosidase were also understood by computational molecular docking studies. PN300 was significantly more effective in reducing CFUs compared to all other groups (p < 0.05) except 6% NaOCl and 2% CHX (p > 0.05) at all time intervals and both depths. At five minutes, 6% NaOCl and 2% CHX were the most effective in reducing CFUs (p < 0.05). However, no significant difference was found between PN300, 6% NaOCl, and 2% CHX at 10 min (p > 0.05). SEM images also showed the maximum reduction in E. faecalis with PN300, 6% NaOCl, and 2% CHX at five and ten minutes. CLSM images showed the number of dead cells in dentin were highest with PN300 compared to PN100 and saline. There was a reduction in the 484 cm⁻¹ band and an increase in the 870 cm⁻¹ band in the PN300 group. The detailed observations of the docking poses of bioactive compounds and their interactions with key residues of the binding site in all the three docking protocols revealed that the interactions were consistent with reasonable docking and IFD docking scores. PN300 was equally as effective as 6% NaOCl and 2% CHX in reducing the E. faecalis biofilms. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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16 pages, 24534 KiB

Open AccessArticle

The Effects of a Trace Amount of Manganese and the Homogenization on the Recrystallization of Al–7Mg–0.15Ti Alloys

by Yang-Chun Chiu, Tse-An Pan, Guan-Ming Chen, Xin-Cheng Jiang, Hui-Yun Bor, Yu-Chih Tzeng and Sheng-Long Lee

Molecules 2021, 26(1), 168; https://doi.org/10.3390/molecules26010168 - 31 Dec 2020

Cited by 4 | Viewed by 2096

Abstract

The aim of this study is to explore the effects of Manganese addition and homogenization treatment on the microstructures and mechanical properties of the Al–7Mg–0.15Ti (B535.0) alloy. The optical microscopy, electrical conductivity measurements, transmission electron microscopy, scanning electron microscopy (SEM + EBSD), as [...] Read more.

The aim of this study is to explore the effects of Manganese addition and homogenization treatment on the microstructures and mechanical properties of the Al–7Mg–0.15Ti (B535.0) alloy. The optical microscopy, electrical conductivity measurements, transmission electron microscopy, scanning electron microscopy (SEM + EBSD), as well as Rockwell hardness and tensile tests, were exploited for this purpose. The main objectives are to refine the grain size, inhibit grain growth in the annealed state, and enhance the mechanical strength of the alloy. The results show that the addition of manganese to the Al–7Mg–0.15Ti alloys refined the as-cast and recrystallized grains of the alloys. During the homogenization process, Al₄Mn high-temperature stable dispersoids were precipitated in the aluminum matrix. After annealing, the Al₄Mn particles blocked the movement of grain boundaries during the growth of the recrystallized grains and inhibited grain growth. Consequently, the annealed alloys showed grain refinement and dispersion strengthening. The Al₄Mn dispersoids of the alloys with manganese added were smaller and denser after a two-stage homogenization process compared to those that underwent a one-stage homogenization process. By contrast, for the alloys without the addition of manganese, the recrystallized grains showed normal growth after annealing, and different homogenization processes had no significantly different effects. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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10 pages, 2699 KiB

Open AccessArticle

A Study of the Effect of Sintering Conditions of Mg_0.95Ni_0.05Ti₃ on Its Physical and Dielectric Properties

by Chun-Hsu Shen, Chung-Long Pan and Shih-Hung Lin

Molecules 2020, 25(24), 5988; https://doi.org/10.3390/molecules25245988 - 17 Dec 2020

Cited by 4 | Viewed by 2058

Abstract

Mg_0.95Ni_0.05TiO₃ ceramics were prepared by traditional solid-state route using sintering temperatures between 1300 and 1425 °C and holding time of 2–8 h. The sintered samples were characterized for their phase composition, micro-crystalline structure, unit–cell constant, and dielectric properties. [...] Read more.

Mg_0.95Ni_0.05TiO₃ ceramics were prepared by traditional solid-state route using sintering temperatures between 1300 and 1425 °C and holding time of 2–8 h. The sintered samples were characterized for their phase composition, micro-crystalline structure, unit–cell constant, and dielectric properties. A two-phase combination region was identified over the entire compositional range. The effect of sintering conditions was analyzed for various properties. Both permittivity (ε_r) and Q factor (Q_f) were sensitive to sintering temperatures and holding times, and the optimum performance was found at 1350 °C withholding time of 4 h. The temperature coefficient of resonant frequency (τ_f) in a range from −45.2 to −52 (ppm/°C) and unit–cell constant were not sensitive to both the sintering temperature and holding time. An optimized Q factor of 192,000 (GHz) related with a permittivity (ε_r) of 17.35 and a temperature coefficient (τ_f) of −47 (ppm/°C) was realized for the specimen sintered at 1350 °C withholding time of 4 h. For applications of 5G communication device (filter, antennas, etc.), Mg_0.95Ni_0.05TiO₃ is considered to be a suitable candidate for substrate materials. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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12 pages, 3322 KiB

Open AccessCommunication

Pandemic-Driven Development of a Medical-Grade, Economic and Decentralized Applicable Polyolefin Filament for Additive Fused Filament Fabrication

by Felix Burkhardt, Carl G. Schirmeister, Christian Wesemann, Massimo Nutini, Stefano Pieralli, Erik H. Licht, Marc Metzger, Frederik Wenz, Rolf Mülhaupt and Benedikt C. Spies

Molecules 2020, 25(24), 5929; https://doi.org/10.3390/molecules25245929 - 15 Dec 2020

Cited by 10 | Viewed by 3757

Abstract

A polyolefin with certified biocompatibility according to USP class VI was used by our group as feedstock for filament-based 3D printing to meet the highest medical standards in order to print personal protective equipment for our university hospital during the ongoing pandemic. Besides [...] Read more.

A polyolefin with certified biocompatibility according to USP class VI was used by our group as feedstock for filament-based 3D printing to meet the highest medical standards in order to print personal protective equipment for our university hospital during the ongoing pandemic. Besides the chemical resistance and durability, as well as the ability to withstand steam sterilization, this polypropylene (PP) copolymer is characterized by its high purity, as achieved by highly efficient and selective catalytic polymerization. As the PP copolymer is suited to be printed with all common printers in fused filament fabrication (FFF), it offers an eco-friendly cost–benefit ratio, even for large-scale production. In addition, a digital workflow was established focusing on common desktop FFF printers in the medical sector. It comprises the simulation-based optimization of personalized print objects, considering the inherent material properties such as warping tendency, through to validation of the process chain by 3D scanning, sterilization, and biocompatibility analysis of the printed part. This combination of digital data processing and 3D printing with a sustainable and medically certified material showed great promise in establishing decentralized additive manufacturing in everyday hospital life to meet peaks in demand, supply bottlenecks, and enhanced personalized patient treatment. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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10 pages, 1749 KiB

Open AccessArticle

Interactive Field Effect of Atomic Bonding Forces on the Equivalent Elastic Modulus Estimation of Micro-Level Single-Crystal Copper by Utilizing Atomistic-Continuum Finite Element Simulation

by Chang-Chun Lee and Jing-Yan He

Molecules 2020, 25(21), 5107; https://doi.org/10.3390/molecules25215107 - 3 Nov 2020

Viewed by 2261

Abstract

This study uses the finite element analysis (FEA)-based atomistic-continuum method (ACM) combined with the Morse potential of metals to determine the effects of the elastic modulus (E) of a given example on atomic-level single-crystal copper (Cu). This work aims to overcome [...] Read more.

This study uses the finite element analysis (FEA)-based atomistic-continuum method (ACM) combined with the Morse potential of metals to determine the effects of the elastic modulus (E) of a given example on atomic-level single-crystal copper (Cu). This work aims to overcome the estimated drawback of a molecular dynamic calculation applied to the mechanical response of macro in-plane-sized and atomic-level-thick metal-based surface coatings. The interactive energy of two Cu atoms within a face-centered metal lattice was described by a mechanical response of spring stiffness. Compared with the theoretical value, the parameters of the Morse potential dominated the predicted accuracy through the FEA-based ACM. Moreover, the analytic results indicated that the effective E of a single-crystal Cu was significantly sensitive to the given range of the interactive force field among atoms. The reliable elastic moduli of 86.8, 152.6, and 205.2 GPa along the Cu(100), Cu(110), and Cu(111) orientations of the Cu metal were separately acquired using the presented FEA-based ACM methodology. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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17 pages, 15000 KiB

Open AccessArticle

Process Optimization of Ultra-High Molecular Weight Polyethylene/Cellulose Nanofiber Bionanocomposites in Triple Screw Kneading Extruder by Response Surface Methodology

by Nur Sharmila Sharip, Hidayah Ariffin, Yoshito Andou, Yuki Shirosaki, Ezyana Kamal Bahrin, Mohammad Jawaid, Paridah Md Tahir and Nor Azowa Ibrahim

Molecules 2020, 25(19), 4498; https://doi.org/10.3390/molecules25194498 - 30 Sep 2020

Cited by 8 | Viewed by 2831

Abstract

Incorporation of nanocellulose could improve wear resistance of ultra-high molecular weight polyethylene (UHMWPE) for an artificial joint application. Yet, the extremely high melt viscosity of the polymer may constrict the mixing, leading to fillers agglomeration and poor mechanical properties. This study optimized the [...] Read more.

Incorporation of nanocellulose could improve wear resistance of ultra-high molecular weight polyethylene (UHMWPE) for an artificial joint application. Yet, the extremely high melt viscosity of the polymer may constrict the mixing, leading to fillers agglomeration and poor mechanical properties. This study optimized the processing condition of UHMWPE/cellulose nanofiber (CNF) bionanocomposite fabrication in triple screw kneading extruder by using response surface methodology (RSM). The effect of the process parameters—temperature (150–190 °C), rotational speed (30–60 rpm), and mixing time (30–45 min)—on mechanical properties of the bionanocomposites was investigated. Homogenous filler distribution, as confirmed by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis, was obtained through the optimal processing condition of 150 °C, 60 rpm, and 45 min. The UHMWPE/CNF bionanocomposites exhibited improved mechanical properties in terms of Young’s and flexural modulus by 11% and 19%, respectively, as compared to neat UHMWPE. An insignificant effect was observed when maleic anhydride-grafted-polyethylene (MAPE) was added as compatibilizer. The obtained results proved that homogenous compounding of high melt viscosity UHMWPE with CNF was feasible by optimizing the melt blending processing condition in triple screw kneading extruder, which resulted in improved stiffness, a contributing factor for wear resistance. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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16 pages, 8192 KiB

Open AccessArticle

Conversion of Non-Optical Material to Photo-Active Nanocomposites through Non-Conventional Techniques for Water Purification by Solar Energy

by Osama Saber, Adil Alshoaibi, Mohammed Al-Yaari and Mostafa Osama

Molecules 2020, 25(19), 4484; https://doi.org/10.3390/molecules25194484 - 30 Sep 2020

Cited by 9 | Viewed by 2423

Abstract

Development of optical materials has attracted strong attention from scientists across the world to obtain low band gap energy and become active in field of solar energy. This challenge, which cannot be accomplished by the usual techniques, has overcome through the current study [...] Read more.

Development of optical materials has attracted strong attention from scientists across the world to obtain low band gap energy and become active in field of solar energy. This challenge, which cannot be accomplished by the usual techniques, has overcome through the current study using non-conventional techniques. This study has used explosive reactions to convert non-optical alumina to series of new optical nanocomposites with very low band gap energy for the first time. In this trend, alumina nanoparticles were prepared and modified by explosive reactions using ammonium nitrate as a solid fuel. By using methanol or ethanol as a source of carbon species, three nanocomposites were produced indicating a gradual reduction of the band gap energy of alumina from 4.34 eV to 1.60 eV. These nanocomposites were obtained by modifying alumina via two different carbon species; core-shell structure and carbon nanotubes. This modification led to sharp reduction for the band gap energy to become very sensitive in sunlight. Therefore, these nanocomposites caused fast decolorization and mineralization of green dyes after illuminating in sunlight for ten minutes. Finally, it can be concluded that reduction of the band gap energy introduces new optical materials for developing optical nano-devices and solar cells. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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18 pages, 9551 KiB

Open AccessArticle

Hybrid Cellulose–Basalt Polypropylene Composites with Enhanced Compatibility: The Role of Coupling Agent

by Claudia Sergi, Francesca Sbardella, Matteo Lilli, Jacopo Tirillò, Andrea Calzolari and Fabrizio Sarasini

Molecules 2020, 25(19), 4384; https://doi.org/10.3390/molecules25194384 - 24 Sep 2020

Cited by 21 | Viewed by 2838

Abstract

This study deals with the development and optimization of hybrid composites integrating microcrystalline cellulose and short basalt fibers in a polypropylene (PP) matrix to maximize the mechanical properties of resulting composites. To this aim, the effects of two different coupling agents, endowed with [...] Read more.

This study deals with the development and optimization of hybrid composites integrating microcrystalline cellulose and short basalt fibers in a polypropylene (PP) matrix to maximize the mechanical properties of resulting composites. To this aim, the effects of two different coupling agents, endowed with maleic anhydride (MA-g(grafted)-PP) and acrylic acid (AA-g-PP) functionalities, on the composite properties were investigated as a function of their amount. Tensile, flexural, impact and heat deflection temperature tests highlighted the lower reactivity and effectiveness of AA-g-PP, regardless of reinforcement type. Hybrid formulations with basalt/cellulose (15/15) and with 5 wt. % of MA-g-PP displayed remarkable increases in tensile strength and modulus, flexural strength and modulus, and notched Charpy impact strength, of 45% and 284%, 97% and 263%, and 13%, in comparison with neat PP, respectively. At the same time, the thermo-mechanical stability was enhanced by 65% compared to neat PP. The results of this study, if compared with the ones available in the literature, reveal the ability of such a combination of reinforcements to provide materials suitable for automotive applications with environmental benefits. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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14 pages, 3894 KiB

Open AccessArticle

Greener Synthesis of Zinc Oxide Nanoparticles: Characterization and Multifaceted Applications

by Ali Aldalbahi, Seham Alterary, Ruba Ali Abdullrahman Almoghim, Manal A. Awad, Noura S. Aldosari, Shouq Fahad Alghannam, Alhanouf Nasser Alabdan, Shaden Alharbi, Budur Ali Mohammed Alateeq, Atheer Abdulrahman Al Mohsen, Munirah A. Alkathiri and Raghad Abdulrahman Alrashed

Molecules 2020, 25(18), 4198; https://doi.org/10.3390/molecules25184198 - 14 Sep 2020

Cited by 75 | Viewed by 6363

Abstract

Nanoparticles (NPs) have unique properties compared to their bulk counterparts, and they have potentials for various applications in many fields of life science. Green-synthesized NPs have garnered considerable interest due to their inherent features such as rapidity, eco-friendliness and cost-effectiveness. Zinc oxide nanoparticles [...] Read more.

Nanoparticles (NPs) have unique properties compared to their bulk counterparts, and they have potentials for various applications in many fields of life science. Green-synthesized NPs have garnered considerable interest due to their inherent features such as rapidity, eco-friendliness and cost-effectiveness. Zinc oxide nanoparticles (ZnO NPs) were synthesized using an aqueous extract of Kalanchoe blossfeldiana as a reducing agent. The resulting nanoparticles were characterized via X-ray diffraction (XRD), dynamic light scattering (DLS), UV-Vis spectroscopy, photoluminescence (PL), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The antimicrobial potential of the synthesized ZnO NPs against bacterial and fungal strains was examined by the disk diffusion method, and they showed a promising antibacterial and antifungal potential. The catalytic activity of the synthesized ZnO NPs in reducing methylene blue (MB) and eosin was studied via UV-Vis spectroscopy. The decolorization percentages of the MB and Eosin Y dyes were 84% and 94%, respectively, which indicate an efficient degradation of the ZnO NPs. In addition, the cytotoxic activity of the ZnO NPs on the HeLa cell line was evaluated via in vitro assay. The MTT assay results demonstrate a potent cytotoxic effect of the ZnO NPs against the HeLa cancer cell line. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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12 pages, 4404 KiB

Open AccessArticle

Fabrication and Biological Analysis of Highly Porous PEEK Bionanocomposites Incorporated with Carbon and Hydroxyapatite Nanoparticles for Biological Applications

by P. D. Swaminathan, Md. Nizam Uddin, P. Wooley and Ramazan Asmatulu

Molecules 2020, 25(16), 3572; https://doi.org/10.3390/molecules25163572 - 6 Aug 2020

Cited by 20 | Viewed by 2961

Abstract

Bone regeneration for replacing and repairing damaged and defective bones in the human body has attracted much attention over the last decade. In this research, highly porous polyetheretherketone (PEEK)/hydroxyapatite (HA) bionanocomposite scaffolds reinforced with carbon fiber (CF) and carbon nanotubes (CNTs) were fabricated, [...] Read more.

Bone regeneration for replacing and repairing damaged and defective bones in the human body has attracted much attention over the last decade. In this research, highly porous polyetheretherketone (PEEK)/hydroxyapatite (HA) bionanocomposite scaffolds reinforced with carbon fiber (CF) and carbon nanotubes (CNTs) were fabricated, and their structural, mechanical, and biological properties were studied in detail. Salt porogen (200–500 µm size) leaching methods were adapted to produce porous PEEK structures with controlled pore size and distribution, facilitating greater cellular infiltration and biological integration of PEEK composites within patient tissue. In biological tests, nanocomposites proved to be non-toxic and have very good cell viability. In addition, bone marrow cell growth was observed, and PEEK/HA biocomposites with carbon particles showed increased cell attachment over the neat PEEK/HA composites. In cell viability tests, bionanocomposites with 0.5 wt% CNTs established good attachment of cells on disks compared to neat PEEK/HA biocomposites. A similar performance was seen in culture tests of bone marrow cells (osteoblasts and osteoclasts). The 0.5 wt% CF for osteoblasts and 1 wt% CNTs for osteoclasts showed higher cell attachment. The addition of carbon-based nanomaterials into PEEK/HA has been identified as an effective approach to improve cell attachment as well as mechanical and biological properties. With confirmed cell attachment and sustained viability and proliferation of the fabricated PEEK/HA/CNTs, CF bionanocomposites were confirmed to possess excellent biocompatibility and will have potential uses in bone scaffolding and other biomedical applications. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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12 pages, 4517 KiB

Open AccessArticle

Preparation, Characterization, and In Vitro Sustained Release Profile of Resveratrol-Loaded Silica Aerogel

by Lili Qin, Yiwei He, Xinyu Zhao, Ting Zhang, Yao Qin and Ai Du

Molecules 2020, 25(12), 2752; https://doi.org/10.3390/molecules25122752 - 15 Jun 2020

Cited by 36 | Viewed by 3551

Abstract

Silica aerogel, a kind of nanoporous material, is regarded as a desired drug carrier for its low toxicity, high specific surface area, and excellent biocompatibility. Using silica aerogel in a drug carrier may be an appropriate method to improve the performance of pure [...] Read more.

Silica aerogel, a kind of nanoporous material, is regarded as a desired drug carrier for its low toxicity, high specific surface area, and excellent biocompatibility. Using silica aerogel in a drug carrier may be an appropriate method to improve the performance of pure resveratrol. In this study, resveratrol-loaded silica aerogel (RSA) as a drug delivery system was prepared by the sol-gel method. Before gelling, resveratrol was added into the hydrolyzed tetraethyl orthosilicate (TEOS) ethanol solution then dispersed by stir and ultrasound. The results showed that RSA has a high loading rate of 19% with low cost and excellent biocompatibility. The SEM images showed that silica aerogel wraps up outside the resveratrol. Sustained releasing effect could be observed in RSA after 1 h, while pure resveratrol did not display this. The release of RSA lasted for over 6 h, and the release amount reached over 90% and 80% in either simulated gastric fluid (pH = 2.0) or phosphate-buffered saline (pH = 7.4) at 37 °C. Preliminary in vitro toxicity test revealed RSA to be biocompatible and stable; and when coupled with the anti-inflammatory effects of resveratrol, showed good potential for osteoarthritis treatment. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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16 pages, 6413 KiB

Open AccessFeature PaperArticle

Effect of Intra-Ply Hybrid Patches and Hydrothermal Aging on Local Bending Response of Repaired GFRP Composite Laminates

by J. Jefferson Andrew, Vellayaraj Arumugam and Hom N. Dhakal

Molecules 2020, 25(10), 2325; https://doi.org/10.3390/molecules25102325 - 16 May 2020

Cited by 6 | Viewed by 2795

Abstract

This study investigates the influence of intra-ply hybrid patches and hydrothermal aging on the indentation properties of patch repaired GFRP composites. Fabrics with various proportions of glass and Kevlar fibers were employed as the patches to achieve enhanced mechanical properties by hybridizing Kevlar [...] Read more.

This study investigates the influence of intra-ply hybrid patches and hydrothermal aging on the indentation properties of patch repaired GFRP composites. Fabrics with various proportions of glass and Kevlar fibers were employed as the patches to achieve enhanced mechanical properties by hybridizing Kevlar and glass fibers together. Hydrothermal aging behavior of repaired composite laminates modified with water-resistant glass fibers in the outer layers was further investigated. Specimens were immersed in an environmental chamber containing seawater at temperatures of 30 (ambient), 50, and 70 °C until up to saturation. Damage mechanisms of repaired laminates were monitored using real-time acoustic emission (AE) technique. The experimental results showed that specimens repaired with 50G:50K patches offered superior performance than the virgin specimens. The hydrothermal aging effect on indentation behavior of the modified repaired specimens showed a considerable reduction in indentation properties, with higher strength retention exhibited by the repaired specimens modified with chopped glass fibers compared to the particulate fibers. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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Review

Jump to: Research

24 pages, 4324 KiB

Open AccessReview

Benzil Photoperoxidations in Polymer Films and Crosslinking by the Resultant Benzoyl Peroxides in Polystyrene and Other Polymers

by Ivan Lukáč, Branislav Husár, Martin Danko and Richard G. Weiss

Molecules 2021, 26(17), 5154; https://doi.org/10.3390/molecules26175154 - 25 Aug 2021

Cited by 1 | Viewed by 2845

Abstract

Benzil (BZ) can be converted almost quantitatively to benzoyl peroxide (BP) in aerated polymer films upon irradiation at >400 nm (i.e., the long-wavelength edge of the n→π* absorption band of BZ, where BP does not absorb). [...] Read more.

Benzil (BZ) can be converted almost quantitatively to benzoyl peroxide (BP) in aerated polymer films upon irradiation at >400 nm (i.e., the long-wavelength edge of the n→π* absorption band of BZ, where BP does not absorb). Here, we summarize results for the photoperoxidation of BZ structures with molecular oxygen, principally in glassy polymer matrices. Some of the polymers are doped directly with BZ or its derivatives, and others, contain covalently attached BZ pendant groups from which BP groups are derived. While the decomposition of low-molecular-weight BP doped into polymer films (such as those of polystyrene (PS)) results in a net decrease in polymer molecular weight, thermal decomposition of pendant BP groups is an efficient method for chain crosslinking. Crosslinking of PS films doped with a molecule containing two covalently linked BZ or BP groups proceeds in a similar fashion. Free radicals from the covalently attached BP allow grafting of new monomers, as well. Additionally, the use of radiation filtered through masks has been used to create patterns of polymers on solid surfaces. Crosslinking of photodegradable poly(phenyl vinyl ketone) with BP structures obtained by photoperoxidation of BZ structures for the preparation of photodegradable polymer networks is described as well. In sum, the use of BZ and BP and their derivatives offers simple and convenient routes for modifying polymer chains and, especially, for crosslinking them. Specific applications of each use and process are provided. Although applications with PS are featured here, the methodologies described are amenable to a wide variety of other polymers. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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19 pages, 2895 KiB

Open AccessReview

Infrared Polaritonic Biosensors Based on Two-Dimensional Materials

by Guangyu Du, Xiaozhi Bao, Shenghuang Lin, Huan Pang, Shivananju Bannur Nanjunda and Qiaoliang Bao

Molecules 2021, 26(15), 4651; https://doi.org/10.3390/molecules26154651 - 31 Jul 2021

Cited by 3 | Viewed by 3894

Abstract

In recent years, polaritons in two-dimensional (2D) materials have gained intensive research interests and significant progress due to their extraordinary properties of light-confinement, tunable carrier concentrations by gating and low loss absorption that leads to long polariton lifetimes. With additional advantages of biocompatibility, [...] Read more.

In recent years, polaritons in two-dimensional (2D) materials have gained intensive research interests and significant progress due to their extraordinary properties of light-confinement, tunable carrier concentrations by gating and low loss absorption that leads to long polariton lifetimes. With additional advantages of biocompatibility, label-free, chemical identification of biomolecules through their vibrational fingerprints, graphene and related 2D materials can be adapted as excellent platforms for future polaritonic biosensor applications. Extreme spatial light confinement in 2D materials based polaritons supports atto-molar concentration or single molecule detection. In this article, we will review the state-of-the-art infrared polaritonic-based biosensors. We first discuss the concept of polaritons, then the biosensing properties of polaritons on various 2D materials, then lastly the impending applications and future opportunities of infrared polaritonic biosensors for medical and healthcare applications. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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16 pages, 783 KiB

Open AccessReview

Advances of Anti-Caries Nanomaterials

by Hui Chen, Lisha Gu, Binyou Liao, Xuedong Zhou, Lei Cheng and Biao Ren

Molecules 2020, 25(21), 5047; https://doi.org/10.3390/molecules25215047 - 30 Oct 2020

Cited by 34 | Viewed by 6016

Abstract

Caries is the most common and extensive oral chronic disease. Due to the lack of anti-caries properties, traditional caries filling materials can easily cause secondary caries and lead to treatment failure. Nanomaterials can interfere with the bacteria metabolism, inhibit the formation of biofilm, [...] Read more.

Caries is the most common and extensive oral chronic disease. Due to the lack of anti-caries properties, traditional caries filling materials can easily cause secondary caries and lead to treatment failure. Nanomaterials can interfere with the bacteria metabolism, inhibit the formation of biofilm, reduce demineralization, and promote remineralization, which is expected to be an effective strategy for caries management. The nanotechnology in anti-caries materials, especially nano-adhesive and nano-composite resin, has developed fast in recent years. In this review, the antibacterial nanomaterials, remineralization nanomaterials, and nano-drug delivery systems are reviewed. We are aimed to provide a theoretical basis for the future development of anti-caries nanomaterials. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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29 pages, 1809 KiB

Open AccessReview

Hybrid Polymer Composites of Bio-Based Bast Fibers with Glass, Carbon and Basalt Fibers for Automotive Applications—A Review

by Anjum Saleem, Luisa Medina, Mikael Skrifvars and Lena Berglin

Molecules 2020, 25(21), 4933; https://doi.org/10.3390/molecules25214933 - 25 Oct 2020

Cited by 42 | Viewed by 4941

Abstract

Composites with reinforcements based on bast fibers such as flax, hemp and kenaf offer many advantages such as weight reduction, improved specific impact, flexural, acoustic properties, and balanced performance to cost that can be achieved by properly designing the material composition. Their position [...] Read more.

Composites with reinforcements based on bast fibers such as flax, hemp and kenaf offer many advantages such as weight reduction, improved specific impact, flexural, acoustic properties, and balanced performance to cost that can be achieved by properly designing the material composition. Their position is well established, especially in the nonstructural automotive applications. However, in structural applications of composites, their mechanical property profile is not comparable to the dominant reinforcements such as glass and carbon fibers. The low mechanical properties of these composites could be improved by hybridization that involves adding high-performance fibers to the bast fiber composites that could improve the low mechanical performance of the bast fiber composites. The review presented in this article provides an overview of the developments in the field of hybrid polymer composites composed of bio-based bast fibers with glass, carbon, and basalt fibers. The focus areas are the composite manufacturing methods, the influence of hybridization on the mechanical properties, and the applications of hybrid composites. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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19 pages, 1374 KiB

Open AccessReview

All-Cellulose Composites: A Review of Recent Studies on Structure, Properties and Applications

by Behnaz Baghaei and Mikael Skrifvars

Molecules 2020, 25(12), 2836; https://doi.org/10.3390/molecules25122836 - 19 Jun 2020

Cited by 102 | Viewed by 9313

Abstract

Nowadays, there is greater demand for greener materials in societies due to environmental consciousness, depleting fossil fuels and growing ecological concerns. Within the foreseeable future, industries and suppliers will be required to be more aware of challenges faced due to the availability of [...] Read more.

Nowadays, there is greater demand for greener materials in societies due to environmental consciousness, depleting fossil fuels and growing ecological concerns. Within the foreseeable future, industries and suppliers will be required to be more aware of challenges faced due to the availability of resources and use more sustainable and renewable raw materials. In this context, cellulose can be expected to become a vital resource for materials owing to its abundance, versatility as a biopolymer, several different forms and potential applications. Thus, all-cellulose composites (ACCs) have gained significant research interest in recent years. ACC is a class of biocomposites in which the matrix is a dissolved and regenerated cellulose, while the reinforcement is undissolved or partly dissolved cellulose. This review paper is intended to provide a brief outline of works that cover recent progress in the manufacturing and processing techniques for ACCs, various cellulose sources, solvents and antisolvents, as well as their properties. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Materials Chemistry)

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