Research

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26 pages, 59916 KiB

Open AccessArticle

Alginate–Moroccan Clay, New Bio-Nanocomposite for Removal of H₂PO₄⁻, HPO₄²⁻, and NO₃⁻ Ions from Aqueous Solutions

by Rachid Aziam, Daniela Simina Stefan, Abdelali Aboussabek, Mohamed Chiban and Alexa-Maria Croitoru

Polymers 2023, 15(24), 4666; https://doi.org/10.3390/polym15244666 - 11 Dec 2023

Cited by 1 | Viewed by 767

Abstract

The aim of this work is to synthesize and characterize alginate–Moroccan clay bio-composite in order to improve our understanding of the adsorption of inorganic pollutants found in textile effluents. Characterization of the bio-composite used was carried out using a variety of techniques (IR-TF, [...] Read more.

The aim of this work is to synthesize and characterize alginate–Moroccan clay bio-composite in order to improve our understanding of the adsorption of inorganic pollutants found in textile effluents. Characterization of the bio-composite used was carried out using a variety of techniques (IR-TF, SEM, DRX, and pH_ZPC). The influence of the medium’s physico-chemical parameters (temperature, pH, initial concentration, etc.) on the retention of inorganic pollutants was also studied. Studies of adsorption and inorganic pollutants such as orthophosphate (H₂PO₄⁻ and HPO₄²⁻) and nitrate (NO₃⁻) ions were carried out, using simple solutions from the laboratory, in a batch system. This study explored the impact of adsorbent dose, contact time, solution pH, and temperature on the adsorption process. Various kinetic models, including pseudo-first-order, pseudo-second-order, intra-particle diffusion, and Elovich models, were tested and evaluated, to illustrate the adsorption kinetics. This study’s findings demonstrated that the adsorption process follows second-order kinetics, with associated rate constants successfully determined. The correlation coefficient for the pseudo-second-order kinetic model is nearly equal to 1 (>0.98), and the value of theoretical adsorption capacity (q_e_,the) is comparable to the experimental one (q_e_,the = 58.14 mg/g for H₂PO₄⁻, q_e_,the = 54.64 mg/g for HPO₄²⁻, and q_e_,the = 52.63 mg/g for NO₃⁻). Additionally, the adsorption equilibrium was investigated through the application of various mathematical models, including the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm models, to assess the mechanistic parameters associated with the adsorption process. Among these models, the Langmuir isotherm emerged as the most suitable one for characterizing the adsorption of H₂PO₄⁻, HPO₄²⁻, and NO₃⁻ ions using bio-nanocomposite beads. The maximum adsorbed amounts of metal ions by the bio-nanocomposite used were 625 mg/g for H₂PO₄⁻, 909.09 mg/g for HPO₄²⁻, and 588.23 mg/g for NO₃⁻ from the batch system. The endothermic and physical nature of the adsorption is suggested by the positive values of ΔH°, which is consistent with experimental findings. The adsorption process is spontaneous, as evidenced by the negative ΔG° values. Positive ΔS° values indicate increased randomness at the solid/liquid interface during adsorption of ion-organic ions onto the engineered bio-nanocomposite. The obtained results demonstrated that, from a scientific perspective, alginate–Moroccan clay bio-nanocomposites exhibit a highly significant adsorption capability for the removal of oxyanions in aqueous environments. Full article

(This article belongs to the Special Issue Conjugated Polymer Nanocomposites: Synthesis, Characterization, and Applications)

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15 pages, 2271 KiB

Open AccessArticle

Development of a New Clay-Based Aerogel Composite from Ball Clay from Piauí, Brazil and Polysaccharides

by Wilton C. Lopes, Francisco M. Brito, Francisco E. Neto, Alyne R. Araújo, Rodolpho C. Leite, Vicente G. Freitas Viana, Edson C. Silva-Filho and Durcilene A. Silva

Polymers 2023, 15(11), 2412; https://doi.org/10.3390/polym15112412 - 23 May 2023

Viewed by 1392

Abstract

The incorporation of polymeric components into aerogels based on clay produces a significant improvement in the physical and thermal properties of the aerogels. In this study, clay-based aerogels were produced from a ball clay by incorporation of angico gum and sodium alginate using [...] Read more.

The incorporation of polymeric components into aerogels based on clay produces a significant improvement in the physical and thermal properties of the aerogels. In this study, clay-based aerogels were produced from a ball clay by incorporation of angico gum and sodium alginate using a simple, ecologically acceptable mixing method and freeze-drying. The compression test showed a low density of spongy material. In addition, both the compressive strength and the Young’s modulus of elasticity of the aerogels showed a progression associated to the decrease in pH. The microstructural characteristics of the aerogels were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The chemical structure was studied by infrared spectroscopy with Fourier transform (FTIR). The TGA curves from a non-oxidizing atmosphere indicated that the clay had a mass loss of 9% above 500 °C and that due to the presence of polysaccharides, the aerogels presented a decomposition of 20% at temperatures above 260 °C. The DSC curves of the aerogels demonstrated a displacement in higher temperatures. In conclusion, the results showed that aerogels of ball clay with the incorporation of polysaccharides, which are still minimally studied, have potential application as thermal insulation considering the mechanical and thermal results obtained. Full article

(This article belongs to the Special Issue Conjugated Polymer Nanocomposites: Synthesis, Characterization, and Applications)

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17 pages, 5824 KiB

Open AccessArticle

Peptide-Enabled Nanocomposites Offer Biomimetic Reconstruction of Silver Diamine Fluoride-Treated Dental Tissues

by Sarah Kay Woolfolk, Aya Kirahm Cloyd, Qiang Ye, Kyle Boone, Paulette Spencer, Malcolm L. Snead and Candan Tamerler

Polymers 2022, 14(7), 1368; https://doi.org/10.3390/polym14071368 - 28 Mar 2022

Cited by 6 | Viewed by 2584

Abstract

Caries is the most ubiquitous infectious disease of mankind, and early childhood caries (ECC) is the most prevalent chronic disease in children worldwide, with the resulting destruction of the teeth recognized as a global health crisis. Recent the United States Food and Drug [...] Read more.

Caries is the most ubiquitous infectious disease of mankind, and early childhood caries (ECC) is the most prevalent chronic disease in children worldwide, with the resulting destruction of the teeth recognized as a global health crisis. Recent the United States Food and Drug Administration (FDA) approval for the use of silver diamine fluoride (SDF) in dentistry offers a safe, accessible, and inexpensive approach to arrest caries progression in children with ECC. However, discoloration, i.e., black staining, of demineralized or cavitated surfaces treated with SDF has limited its widespread use. Targeting SDF-treated tooth surfaces, we developed a biohybrid calcium phosphate nanocomposite interface building upon the self-assembly of synthetic biomimetic peptides. Here, an engineered bifunctional peptide composed of a silver binding peptide (AgBP) is covalently joined to an amelogenin derived peptide (ADP). The AgBP provides anchoring to the SDF-treated tooth tissue, while the ADP promotes rapid formation of a calcium phosphate isomorph nanocomposite mimicking the biomineralization function of the amelogenin protein. Our results demonstrate that the bifunctional peptide was effective in remineralizing the biomineral destroyed by caries on the SDF-treated tooth tissues. The proposed engineered peptide approach offers a biomimetic path for remineralization of the SDF-treated tissues producing a calcium phosphate nanocomposite interface competent to be restored using commonly available adhesive dental composites. Full article

(This article belongs to the Special Issue Conjugated Polymer Nanocomposites: Synthesis, Characterization, and Applications)

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17 pages, 10071 KiB

Open AccessArticle

Preparation of Large Conjugated Polybenzimidazole Fluorescent Materials and Their Application in Metal Ion Detection

by Xi-Ying Cao, Chu-Ming Pang, Ying Xiao, Wan-Qing Xiao, Shi-He Luo, Jin-Ping He and Zhao-Yang Wang

Polymers 2021, 13(18), 3091; https://doi.org/10.3390/polym13183091 - 14 Sep 2021

Cited by 1 | Viewed by 1890

Abstract

A new type of conjugated polybenzimidazole (CPBI) was synthesized through a simple polycondensation reaction without metal catalysis, and N-alkylation modification was carried out to solve the problems of solubility and fluorescence properties. A series of nano-microsphere polymers CPBI_n with [...] Read more.

A new type of conjugated polybenzimidazole (CPBI) was synthesized through a simple polycondensation reaction without metal catalysis, and N-alkylation modification was carried out to solve the problems of solubility and fluorescence properties. A series of nano-microsphere polymers CPBI_n with large conjugation, good solubility, and strong fluorescence has been successfully used as “turn-off” fluorescent probes for the first time. The results show that, under suitable N-alkylation conditions, the obtained CPBI_n can be used as a highly sensitive and selective fluorescent probe for the detection of Cu²⁺ and Zn²⁺ at the same time, and their detection limits are both nM levels. In addition, CPBI₂ can be designed as an ultra-sensitive IMPLICATION logic gate at the molecular level, cyclically detecting Cu²⁺. With the test paper containing CPBI₂, easy and quick on-site detection can be achieved. This research provides a new idea for the brief synthesis of multifunctional materials. Full article

(This article belongs to the Special Issue Conjugated Polymer Nanocomposites: Synthesis, Characterization, and Applications)

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13 pages, 3784 KiB

Open AccessArticle

Enhanced Chemical and Electrochemical Stability of Polyaniline-Based Layer-by-Layer Films

by Putri Bintang Dea Firda, Yoga Trianzar Malik, Jun Kyun Oh, Evan K. Wujcik and Ju-Won Jeon

Polymers 2021, 13(17), 2992; https://doi.org/10.3390/polym13172992 - 03 Sep 2021

Cited by 14 | Viewed by 3418

Abstract

Polyaniline (PANI) has been widely used as an electroactive material in various applications including sensors, electrochromic devices, solar cells, electroluminescence, and electrochemical energy storage, owing to PANI’s unique redox properties. However, the chemical and electrochemical stability of PANI-based materials is not sufficiently high [...] Read more.

Polyaniline (PANI) has been widely used as an electroactive material in various applications including sensors, electrochromic devices, solar cells, electroluminescence, and electrochemical energy storage, owing to PANI’s unique redox properties. However, the chemical and electrochemical stability of PANI-based materials is not sufficiently high to maintain the performance of devices under many practical applications. Herein, we report a route to enhancing the chemical and electrochemical stability of PANI through layer-by-layer (LbL) assembly. PANI was assembled with different types of polyelectrolytes, and a comparative study between three different PANI-based layer-by-layer (LbL) films is presented here. Polyacids of different acidity and molecular structure, i.e., poly(acrylic acid) (PAA), polystyrene sulfonate (PSS), and tannic acid (TA), were used. The effect of polyacids’ acidity on film growth, conductivity, and chemical and electrochemical stability of PANI was investigated. The results showed that the film growth of the LbL system depended on the acidic strength of the polyacids. All LbL films exhibited improved chemical and electrochemical stability compared to PANI films. The doping level of PANI was strongly affected by the type of dopants, resulting in different chemical and electrochemical properties; the strongest polyacid (PSS) can provide the highest conductivity and chemical stability of conductive PANI. However, the electrochemical stability of PANI/PAA was found to be better than all the other films. Full article

(This article belongs to the Special Issue Conjugated Polymer Nanocomposites: Synthesis, Characterization, and Applications)

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Review

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29 pages, 5817 KiB

Open AccessFeature PaperReview

Recent Developments and Implementations of Conductive Polymer-Based Flexible Devices in Sensing Applications

by Vinh Van Tran, Sanghyuck Lee, Daeho Lee and Thanh-Hai Le

Polymers 2022, 14(18), 3730; https://doi.org/10.3390/polym14183730 - 07 Sep 2022

Cited by 20 | Viewed by 6024

Abstract

Flexible sensing devices have attracted significant attention for various applications, such as medical devices, environmental monitoring, and healthcare. Numerous materials have been used to fabricate flexible sensing devices and improve their sensing performance in terms of their electrical and mechanical properties. Among the [...] Read more.

Flexible sensing devices have attracted significant attention for various applications, such as medical devices, environmental monitoring, and healthcare. Numerous materials have been used to fabricate flexible sensing devices and improve their sensing performance in terms of their electrical and mechanical properties. Among the studied materials, conductive polymers are promising candidates for next-generation flexible, stretchable, and wearable electronic devices because of their outstanding characteristics, such as flexibility, light weight, and non-toxicity. Understanding the interesting properties of conductive polymers and the solution-based deposition processes and patterning technologies used for conductive polymer device fabrication is necessary to develop appropriate and highly effective flexible sensors. The present review provides scientific evidence for promising strategies for fabricating conductive polymer-based flexible sensors. Specifically, the outstanding nature of the structures, conductivity, and synthesis methods of some of the main conductive polymers are discussed. Furthermore, conventional and innovative technologies for preparing conductive polymer thin films in flexible sensors are identified and evaluated, as are the potential applications of these sensors in environmental and human health monitoring. Full article

(This article belongs to the Special Issue Conjugated Polymer Nanocomposites: Synthesis, Characterization, and Applications)

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20 pages, 6329 KiB

Open AccessReview

Photodynamic Antimicrobial Therapy Based on Conjugated Polymers

by Huanxiang Yuan, Zelin Li, Xiaoyu Wang and Ruilian Qi

Polymers 2022, 14(17), 3657; https://doi.org/10.3390/polym14173657 - 03 Sep 2022

Cited by 12 | Viewed by 2215

Abstract

Pathogenic microorganisms have been a serious threat to human life and have become a public health problem of global concern. However, in the actual treatment there is a lack of efficient antimicrobial strategies which do not easily develop drug resistance; this can lead [...] Read more.

Pathogenic microorganisms have been a serious threat to human life and have become a public health problem of global concern. However, in the actual treatment there is a lack of efficient antimicrobial strategies which do not easily develop drug resistance; this can lead to inaccurate drug treatment that worsens the infection and even threatens life. With the emergence of a variety of drug-resistant bacteria and fungi, photodynamic therapy has gradually become one of the most promising treatment methods for drug-resistant bacteria infection; this is because it is controllable, non-invasive, and not prone to cause the development of drug resistance. Organic conjugated polymers that possess high fluorescence intensity, a large molar extinction coefficient, excellent light stability, an adjustable energy band, easy modification, good biocompatibility, and the ability to photosensitize oxygen to produce reactive oxygen species have been widely used in the fields of solar cells, highly sensitive detection systems, biological imaging, and anti-cancer and anti-microbial treatment. Photodynamic therapy is non-invasive and has high temporal and spatial resolution and is a highly effective antimicrobial treatment that does not easily induce drug resistance; it has also stimulated the scientific research enthusiasm of researchers and has become a research hotspot in the antimicrobial field. In this review, the photodynamic antibacterial applications of conjugated polymers with different structure types are summarized, and their development directions are considered. Full article

(This article belongs to the Special Issue Conjugated Polymer Nanocomposites: Synthesis, Characterization, and Applications)

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19 pages, 2653 KiB

Open AccessReview

Applications of the ROS-Responsive Thioketal Linker for the Production of Smart Nanomedicines

by Arianna Rinaldi, Riccardo Caraffi, Maria Vittoria Grazioli, Natalia Oddone, Luciana Giardino, Giovanni Tosi, Maria Angela Vandelli, Laura Calzà, Barbara Ruozi and Jason Thomas Duskey

Polymers 2022, 14(4), 687; https://doi.org/10.3390/polym14040687 - 11 Feb 2022

Cited by 36 | Viewed by 6708

Abstract

Reactive oxygen species (ROS)-sensitive drug delivery systems (DDS) specifically responding to altered levels of ROS in the pathological microenvironment have emerged as an effective means to enhance the pharmaceutical efficacy of conventional nanomedicines, while simultaneously reducing side effects. In particular, the use of [...] Read more.

Reactive oxygen species (ROS)-sensitive drug delivery systems (DDS) specifically responding to altered levels of ROS in the pathological microenvironment have emerged as an effective means to enhance the pharmaceutical efficacy of conventional nanomedicines, while simultaneously reducing side effects. In particular, the use of the biocompatible, biodegradable, and non-toxic ROS-responsive thioketal (TK) functional group in the design of smart DDS has grown exponentially in recent years. In the design of TK-based DDS, different technological uses of TK have been proposed to overcome the major limitations of conventional DDS counterparts including uncontrolled drug release and off-target effects. This review will focus on the different technological uses of TK-based biomaterials in smart nanomedicines by using it as a linker to connect a drug on the surface of nanoparticles, form prodrugs, as a core component of the DDS to directly control its structure, to control the opening of drug-releasing gates or to change the conformation of the nano-systems. A comprehensive view of the various uses of TK may allow researchers to exploit this reactive linker more consciously while designing nanomedicines to be more effective with improved disease-targeting ability, providing novel therapeutic opportunities in the treatment of many diseases. Full article

(This article belongs to the Special Issue Conjugated Polymer Nanocomposites: Synthesis, Characterization, and Applications)

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25 pages, 4291 KiB

Open AccessEditor’s ChoiceReview

Advanced Photocatalysts Based on Conducting Polymer/Metal Oxide Composites for Environmental Applications

by Vinh Van Tran, Truong Thi Vu Nu, Hong-Ryun Jung and Mincheol Chang

Polymers 2021, 13(18), 3031; https://doi.org/10.3390/polym13183031 - 08 Sep 2021

Cited by 28 | Viewed by 4387

Abstract

Photocatalysts provide a sustainable method of treating organic pollutants in wastewater and converting greenhouse gases. Many studies have been published on this topic in recent years, which signifies the great interest and attention that this topic inspires in the community, as well as [...] Read more.

Photocatalysts provide a sustainable method of treating organic pollutants in wastewater and converting greenhouse gases. Many studies have been published on this topic in recent years, which signifies the great interest and attention that this topic inspires in the community, as well as in scientists. Composite photocatalysts based on conducting polymers and metal oxides have emerged as novel and promising photoactive materials. It has been demonstrated that conducting polymers can substantially improve the photocatalytic efficiency of metal oxides owing to their superior photocatalytic activities, high conductivities, and unique electrochemical and optical properties. Consequently, conducting polymer/metal oxide composites exhibit a high photoresponse and possess a higher surface area allowing for visible light absorption, low recombination of charge carriers, and high photocatalytic performance. Herein, we provide an overview of recent advances in the development of conducting polymer/metal oxide composite photocatalysts for organic pollutant degradation and CO₂ conversion through photocatalytic processes. Full article

(This article belongs to the Special Issue Conjugated Polymer Nanocomposites: Synthesis, Characterization, and Applications)

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