Search Results (77)

This work investigates the incorporation of sewage sludge-derived biochar (BC) into a recycled poly(ethylene terephthalate) (rPET) matrix at loadings ranging from 0.5 to 5% wt. in order to develop sustainable nanocomposite materials. The materials were comprehensively characterized using complementary structural, thermal, and morphological techniques to evaluate the effect of BC on the properties of the recycled polymer. XRD, DSC, and PLM analyses demonstrated that BC acts as a heterogeneous nucleating agent, without significantly altering the final crystalline fraction of rPET, while SEM observations confirmed the homogeneous dispersion of particles within the matrix. TGA and Py–GC/MS further indicated that BC moderates thermal degradation, reducing the relative formation of low-molecular-weight degradation products and promoting the retention of larger terephthalate-containing fragments. Accelerated UV irradiation experiments further demonstrated the protective role of BC against photo-induced degradation. Intrinsic viscosity (IV) measurements showed that BC-containing nanocomposites exhibited a smaller molecular-weight reduction after UV exposure compared to neat rPET, indicating reduced chain scission, while complementary DSC analyses confirmed improved preservation of thermal transitions after aging. Overall, sewage sludge-derived biochar is demonstrated to be a promising multifunctional additive for rPET, acting both as a nucleating agent and a UV stabilizer. This approach provides an alternative route for the valorization of two waste streams, contributing to enhanced materials in a circular economy framework. Full article

Background/Objectives: α-lipoic acid (ALA) shows therapeutic potential but faces poor aqueous solubility (BCS Class II), gastric instability, and low oral bioavailability (~30%). This work investigated the formulation of cyclodextrin (CD) inclusion complexes of ALA to overcome the aforementioned limitations and improve nutraceutical applications. Methods: Phase solubility studies in simulated gastric and intestinal fluids screened for optimal CD, followed by molecular dynamics simulations and MM-PBSA binding free energy calculations. Inclusion complexes of choice were prepared by grinding, spray-drying, and lyophilization, followed by solid-state characterization (DSC/XRPD/FTIR). Further analysis was performed using pH-shift dissolution (USP II), permeability (PermeaPad^®, Caco-2), and (photo)stability according to ICH. Results: Hydroxypropyl-β-cyclodextrin (HPβCD) emerged as the optimal host due to favorable complexation, as confirmed by phase solubility studies and supported by molecular modeling, which revealed a favorable balance between inclusion complex stability and pH-triggered drug release. Formulations based on spray-dried and lyophilized HPβCD–ALA complexes (HPβALA-sd and HPβALA-lyo), in which ALA was fully amorphized, achieved near-complete dissolution within five minutes under biorelevant pH-shift conditions. This performance markedly exceeded that of free ALA (approximately 66% dissolution at pH 7.4) while maintaining moderate permeability (Papp 8–9 × 10⁻⁶ cm/s). Storage stability was enhanced markedly (88–90% ALA retention after 6 months at 40 °C/75% RH vs. 36% for free ALA) while UV stability was not improved through CD-complexation, probably due to interaction of UV-VIS light with the exposed portion of ALA. Conclusions: Even though the permeability of ALA–CD inclusion complexes remained medium (Papp ~ 8–9 × 10⁻⁶ cm/s) and unaffected by complexation, a significantly improved dissolution profile indicates better expected bioavailability compared to pure ALA. Full article

This study investigates the development and performance of polyolefin-based packaging materials reinforced with industrial mineral residues, specifically slate powder (SP) and bivalve shell powder (BSP). High-density polyethylene (HDPE) and polypropylene (PP) matrices were compounded with these fillers and processed by extrusion blow moulding to produce final prototypes. Thermal analyses (TGA and DSC) showed that incorporating SP and BSP does not compromise the thermal stability of the polymer matrices and increases stiffness in the filled formulations. Accelerated ageing (QUV, 200 h) revealed distinct photo-oxidative behaviours. PP and PP + BSP (30%) exhibited increased fragility and moderate colour changes, whereas PP + SP (10%) retained flexibility, indicating a partial protective effect of SP. HDPE-based formulations showed higher intrinsic UV resistance, with HDPE + BSP (30%) displaying excellent colour stability. Tensile tests before and after QUV exposure confirmed that fillers increase stiffness with limited influence on tensile strength. Air permeability results indicated that neat PP and HDPE were below the detection limit. At the same time, filled formulations exhibited measurable permeability, suggesting that filler incorporation may influence gas transport through interfacial effects. Overall, the results show that SP and BSP act as reinforcing additives and can modify functional properties such as stiffness and ageing resistance. However, their influence on barrier performance depends on the formulation and permeation mechanism. Full article

Heterogeneous photocatalysis increasingly requires rapid polymer degradation tests relevant to aqueous conditions. In this study, a multi-technique approach was developed to monitor the early-stage photo-oxidation of polyethylene (PE) and polystyrene (PS) microplastics in an aqueous ZnO–TiO₂ suspension under combined ultraviolet A and ultraviolet B (UV-A/B) irradiation. The changes were analyzed by ATR-FTIR and Raman spectroscopy, DSC, and gravimetric measurements. For PE, the carbonyl index increased from 0.0189 to 0.1350 after 12 h, mass loss reached 16.98%, and crystallinity decreased from 32.05% to 25.36% after 8 h. The Raman spectra of PE showed band broadening and intensity redistribution, indicating increasing structural disorder. In contrast, PS showed weaker Raman changes, while FTIR revealed a non-monotonic carbonyl-index response, and DSC showed a 2.2 °C increase in Tg after 12 h. Gravimetric analysis also showed measurable mass loss in PS, reaching 18.62% after 12 h. The results demonstrate that the combined use of ATR-FTIR, Raman, DSC, and gravimetry enables reliable distinction between early oxidation, surface modification, and material erosion in photocatalytically treated microplastics. Full article

Photo-thermo-refractive (PTR) glass is a key material for optical devices, yet the synergistic mechanism between its raw material precursors remains unclear. This study systematically investigates the individual and combined effects of silver precursors (Ag₂O and AgNO₃) and sodium salts (Na₂CO₃ and NaNO₃) on the structural evolution and crystallization behavior of Si-Na-Al-Zn-based PTR glasses. Through a combination of spectroscopic (UV-Vis, FTIR, Raman), thermal (DSC), and microscopic (SEM) characterizations, we demonstrate that the precursor combination profoundly influences the glass network homogeneity, ion mobility, and phase separation behavior. The results reveal that the AgNO₃ and NaNO₃ combination fosters a highly homogeneous and thermally stable network, facilitating the formation of a uniform distribution of silver nanoparticles and, subsequently, a dense nanoscale precipitation of NaF crystals. This work elucidates the critical synergistic mechanism between precursors, providing a fundamental basis for the precise composition design of high-performance PTR glasses for advanced optical applications. Full article

In this study, we report a reproducible in situ photochemical method for the simultaneous synthesis of metallic and hybrid metal/metal oxide nanoparticles (NPs) within a UV–curable polymer matrix. A series of epoxy diacrylate-based formulations (BEA) was prepared, consisting of Epoxy diacrylate, Di(Ethylene glycol)ethyl ether acrylate (DEGEEA), and Phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (BAPO), which served as a Type I photoinitiator. These formulations were designed to enable the simultaneous photopolymerization and photoreduction of metal precursors at various Ag⁺/Co²⁺ ratios, resulting in nanocomposites containing in situ-formed Ag NPs, cobalt oxide NPs, and hybrid Ag–Co₃O₄ nanostructures. The photochemical, magnetic, and dielectric properties of the resulting nanocomposites were evaluated in comparison with those of the pure polymer using UV–Vis and Fourier Transform Infrared Spectroscopy (FT-IR), Photo-Differential Scanning Calorimetry (Photo-DSC), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Impedance Analysis, and Vibrating Sample Magnetometry (VSM). Photo-DSC studies revealed that the highest conversion values were obtained for the BEA-Ag₁Co₁, BEA-Co, and BEA-Ag₁Co₂ samples, demonstrating that the presence of Co₃O₄ NPs enhances polymerization efficiency because of cobalt species participating in redox-assisted radical generation under UV irradiation, increasing the number of initiating radicals and leading to faster curing and higher final conversion. On the other hand, the Ag NPs, due to the SPR band formation at around 400 nm, compete with photoinitiator absorbance and result in a gradual decrease in conversion values. Crystal structures of the NPs were confirmed by XRD analyses. The dielectric and magnetic characteristics of the nanocomposites suggest potential applicability in energy-storage systems, electromagnetic interference mitigation, radar-absorbing materials, and related multifunctional electronic applications. Full article

This work characterizes hybrid hydrogels prepared via the combination of natural and synthetic polymers. By incorporating a biocompatible compound, poly(ethylene glycol) diacrylate (PEGDA, M_n = 400), into alginate and carboxymethyl cellulose (CMC)-based hydrogels, the in situ UV crosslinking of these materials was assessed. A custom direct-write (DW) 3D bioprinter was utilized to prepare hybrid hydrogel constructs and scaffolds. A control sample, which consisted of 4% w/v alginate and 4% w/v CMC, was prepared and evaluated in addition to three PEGDA (4.5, 6.5, and 10% w/v)-containing hybrid hydrogels. Rotational rheology was utilized to evaluate the thixotropic behavior of these materials. Filament fusion tests were employed to generate bilayer constructs of various pore sizes, providing metrics for the printability and diffusion rate of hydrogels post-extrusion. Printability indicates the shape fidelity of pore geometry, whereas diffusion rate represents material spreading after deposition. Curing kinetics of PEGDA-containing hydrogels were evaluated using photo-Differential Scanning Calorimetry (DSC) and photorheology. The Kamal model was fitted to photo-DSC results, enabling an assessment and comparison of the curing kinetics for PEGDA-containing hydrogels. Photorheological results highlight the increase in hydrogel stiffness concomitant with PEGDA content. The range of obtained complex moduli (G*) provides utility for the development of brain, kidney, and heart tissue (620–4600 Pa). The in situ UV irradiation of PEGDA-containing hydrogels improved the shape fidelity of printed bilayers and decreased filament diffusion rates. In situ UV irradiation enabled 10-layer scaffolds with 1 × 1 mm pore sizes to be printed. Ultimately, this study highlights the utility of PEGDA-containing hybrid hydrogels for high-resolution DW 3D bioprinting and potential application toward customizable tissue analogs. Full article

The article presents the results of a study of the possibility of using heat-treated ethylene-vinyl acetate copolymer (EVA) as a thermoplastic modifier in a photosensitive composition based on tert-butyl acrylate (tBA). The use of such a modifier in 3D printing compositions is important for improving their physical and mechanical properties at low temperatures. An attempt was also made to use EVA as a polymer chain brancher. The molecular structure of the components and their compositions, rheology, curing kinetics, and phase organization of photocured systems were studied using FTIR and NMR spectroscopy, spectrophotometry, rheometry, Photo-DSC, and scanning electron microscopy. It was found that heat treatment of EVA allows the formation of single C=C bonds in macromolecules, which are necessary for a potential crosslinking agent with tBA. It was shown that EVA effectively functions as a thickener and modifier: with an increase in the modifier concentration, the nature of the composition flow changes from Newtonian to pseudoplastic, the rate of the photochemical polymerization reaction decreases, and the degree of conversion of the system decreases. However, the formation of a heterogeneous phase structure and the absence of a continuous spatial network of chemical bonds prevent the use of EVA simultaneously as a functional additive and crosslinking agent. Full article

This study reports on the preparation and comprehensive characterisation of new brominated hydrogen-bonded liquid crystalline (HBLC) materials. Two distinct series of supramolecular complexes were prepared by hydrogen-bond formation between 3-bromo-4-pentyloxybenzoic acid as the proton donor and non-fluorinated and fluorinated azopyridines with variable terminal chains as proton acceptors. The successful formation of a hydrogen bond was confirmed by FTIR spectroscopy. The impact of alkyl chain length and fluorination on the mesomorphic properties of the HBLCs was systematically investigated. The molecular self-assembly was thoroughly examined using polarised optical microscopy (POM) and differential scanning calorimetry (DSC), revealing the presence of smectic C (SmC), smectic A (SmA), and nematic (N) phases, with thermal stability being highly dependent on the molecular architecture. Notably, the introduction of fluorine atoms significantly influenced the phase transition temperatures and the overall mesophase range. Using bromine as a lateral substituent induces the formation of SmC phases in these HBLCs, a feature absent in their non-brominated analogues. Further structural insights were obtained through X-ray diffraction (XRD) investigations, confirming the nature of the observed LC phases. Additionally, the photo-responsive characteristics of these HBLCs were explored via UV-Vis spectroscopy, demonstrating their ability to undergo reversible photoisomerisation upon light irradiation. These findings underscore the critical role of precise molecular design in tailoring the properties of HBLCs for potential applications such as optical storage devices. Full article

Bio-based polymeric composites were prepared by dispersing different amounts of olive pit (OP) powder within an acrylate epoxidized soybean oil (AESO) photocurable resin using tetrahydrofurfuryl acrylate (THFA) as diluent and (2,4,6-trimethylbenzoyl), phosphine oxide (BAPO) as photo-initiator, and they were photocured by Vat Photopolymerization (VP) using a Liquid Crystal Display (LCD) 3D printer. Formulation viscosity was studied because of its important role in a VP process able to influence the printability of the final parts. Different 3D printed architectures were successfully realized with good resolution and accuracy, high level of detail, and flexibility. The effect of OP addition was investigated by thermal (TGA and DSC), morphological (SEM and PSD), viscoelastic (DMA), and mechanical (tensile testing) characterization. The filler led to an increase in the T_g, storage modulus, and tensile properties, underlining the stiffening effect induced by the OP particles onto the polymeric starting resin. This underlines the possibility to apply these bio-based composites in many application fields by valorizing agro-wastes, developing more sustainable materials, and taking advantages of VP 3D printing, such as low costs, minimal wastage, and customized geometry. Biocompatibility tests were also successfully carried out. The results clearly indicate that the AESO-based composites promote cell adhesion and viability. Full article

We report on the preparation and characterization of a new family of hydrogen-bonded nematogenic liquid crystalline dimers. The dimers are supramolecular complexes that consist of a benzoic acid derivative, acting as the proton donor, featuring a spacer with seven methylene groups and a terminal decyloxy chain, paired with an azopyridine derivative as the proton acceptor. The latter was either fluorinated or nonfluorinated with variable alkoxy chain length. The formation of a hydrogen bond between the individual components was confirmed using FTIR and ¹H NMR spectroscopy. All supramolecules were investigated for their liquid crystalline behaviour via a polarized optical microscope (POM) and differential scanning calorimetry (DSC). All materials exhibit enantiotropic nematic phases as confirmed by X-ray diffraction (XRD) and POM investigations. The nematic phase range depends strongly on the degree and position of fluorine atoms. Additionally, the supramolecules demonstrated a rapid and reversible transition between the liquid crystal phase and the isotropic liquid state because of trans-cis photoisomerization upon light irradiation. Therefore, this study presents a straightforward approach to design photo-responsive nematic materials, which could be of interest for nonlinear optics applications. Full article

Cured-in-place pipe (CIPP) technology is a trenchless rehabilitation method for damaged pipelines in which a resin-saturated liner (often a fiber-reinforced type) is inserted into a host pipe and cured in situ, typically using a UV light beam or steam. This study investigates the influence of selected photoreactive diluents on the photopolymerization process of a styrene-free vinyl ester resin designed for the CIPP applications by evaluating the rheological properties, photopolymerization kinetics (photo-DSC), thermal characteristics (DSC), crosslinking density (gel content), and mechanical properties of thick (15 mm) UV-cured layers. The tested diluents included monofunctional (i.e., methyl methacrylate and vinyl neodecanoate), difunctional (1,6-hexanediol diacrylate, aliphatic urethane acrylates, and an epoxy acrylate), and trifunctional monomers (trimethylolpropane triacrylate, pentaerythritol triacrylate, and trimethylolpropane ethoxylate triacrylate). The key findings demonstrate that the addition of pentaerythritol triacrylate (the most attractive diluent) increases the flexural strength (+6%) and deflection at strength (+28%) at the unchanged flexural modulus value (ca. 2.1 GPa). The difunctional epoxy acrylate caused an even greater increase in the deflection (+52%, at a 5% increase in the flexural strength). Full article

Background: Nabumetone (NAB) is a poorly soluble nonsteroidal anti-inflammatory prodrug (BCS class II drug) whose solubility is significantly improved by complexation with cyclodextrins (CDs). Methods: The solid complexes, in a 1:1 molar ratio, were prepared by mechanochemical activation by grinding, using β-cyclodextrin (β-CD) and its derivatives, hydroxypropyl- and sulfobutylether-β-cyclodextrin (HP-β-CD and SBE-β-CD). The complexation was confirmed by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and attenuated total reflectance Fourier-transformed infrared spectroscopy (ATR–FTIR). Obtained products were further characterized regarding their solubility, in vitro dissolution, permeability and chemical stability. Results: Co-grinding with HP-β-CD and SBE-β-CD yielded products that showed in vitro dissolution profiles in hydrochloric acid medium (pH 1.2) that were substantially different from that of pure NAB, yielding dissolution efficiency enhancements of 34.86 ± 1.64 and 58.30 ± 0.28 times, respectively, for the optimized products. Their in vitro dissolution and gastrointestinal permeability were also studied in a low-volume environment at pH 6.8, corresponding to the intestinal environment. Both β-CD derivatives increased NAB dissolution rate and NAB mass transport across the biomimetic membrane. The effect of β-CD derivatives on NAB chemical stability was studied under the stress conditions by the developed and validated UHPLC–DAD–HRMS method. In acidic conditions, pure and complexed NAB was prone to hydrolytic degradation, yielding one degradation product—pharmacologically inactive NAB metabolite. However, under the oxidative conditions at elevated temperatures, 10 NAB degradation products were identified from co-ground samples. All systems were stable during photo- and long-term stability studies. Conclusions: NAB complexes with HP-β-CD and SBE-β-CD are promising candidates for pharmaceutical product development. Full article

Ionic liquid crystals (ILCs), a class of soft matter materials whose properties can be tuned by the wise pairing of the cation and anion, have recently emerged as promising candidates for different applications, combining the characteristics of ionic liquids and liquid crystals. Among those potential uses, this review aims to cover chromogenic ILCs. In this context, examples of photo-, electro- and thermochromism based on ILCs are provided. Furthermore, thermotropic and lyotropic ionic liquid crystals are also summarised, including the most common chemical and phase structures, as well as the advantages of confining these materials. This manuscript also comprises the following main experimental techniques used to characterise ILCs: Differential Scanning Calorimetry (DSC), Polarised Optical Microscopy (POM) and X-Ray Powder Diffraction (XRD). Chromogenic ILCs can be interesting smart materials for energy and health purposes. Full article

A novel photopolymerizable (meth)acrylate oligomer syrup modified with ferulic acid (FA) was verified as an antimicrobial coating binder against a biofilm of Staphylococcus epidermidis. A solution-free UV-LED-initiated photopolymerization process of aliphatic (meth)acrylates and styrene was performed to prepare the oligomer syrup. The influence of ferulic acid on the UV crosslinking process of the varnish coatings (kinetic studies using photo-DSC) as well as their chemical structure (FTIR) and mechanical (adhesion, hardness), optical (gloss, DOI parameter), and antibacterial properties against S. epidermidis were investigated. The photo-DSC results revealed that FA has a positive effect on reducing the early occurrence of slowing processes and has a favorable effect on the monomer conversion increment. It turned out, unexpectedly, that the more FA in the coating, the greater its adhesion to a glass substrate and hardness. The coating containing 0.9 wt. part of FA exhibited excellent antimicrobial properties against S. epidermidis, i.e., the bacterial number after 24 h was only 1.98 log CFU/mL. All the coatings showed relatively high hardness, gloss (>80 G.U.), and DOI parameter values (30–50 a.u.). Full article