Search Results (1,142)

Novel highly compressible and stretchable nanocomposite (NC) hydrogels were obtained by the free radical polymerization of N-vinylformamide (NVF) in aqueous solution in the presence of Laponite XLG (XLG) as the crosslinker and 2,2′-azobis(2-methylpropionitrile) as the initiator. The expected composition of the NC hydrogels was proved by FTIR, TEM, XRD, and TGA analyses. Swelling degree (SD) and mechanical measurements showed that the properties of the PNVF NC hydrogels were largely different from those of both PNVF hydrogels covalently crosslinked by N,N’-methylenebisacrylamide (MBA) and equivalent poly(N-vinyl-2-pyrrolidone) (PNVP) NC hydrogels. After an initial fast swelling stage, the PNVF NC hydrogels displayed a slow, but steady, SD increase with time, unlike the MBA-crosslinked and NVP hydrogels, which exhibited a much smaller SD change during their second swelling stage. The mechanical testing of the synthesized hydrogels by uniaxial compressive and tensile measurements showed much higher compressibility (>90%) and stretchability (up to ≈840%) in the PNVF NC hydrogels than both PNVP and MBA-crosslinked PNVF hydrogels (compressibility < 80%; stretchability up to ≈114%). Cyclic compression tests revealed higher values for both elastic character and mechanical stability in the PNVF NC hydrogels in comparison to the MBA-crosslinked and PNVP ones. These different mechanical properties were explained by the PNVF NC gels possessing a network made of homogeneously distributed crosslinking sites and flexible polymer chains, thus avoiding extensive chain breakage up to larger stress values. The PNVF NC hydrogels described here may find applications for water purification, due to their high clay content, as well as in the biomedical field based on the biocompatibility of both the polymer and crosslinking agent. Full article

Controlling the rheological properties of liquids allows for the regulation of effective movement, transport of substances, and processes in biological systems. This work presents an experimental investigation into the influence of the proton-exchange polymer membrane Nafion on the surface tension coefficient (STC) of distilled water, aqueous solutions of two methylene blue (MB) forms, and ascorbic acid (AA). Immediately upon membrane immersion in the solutions, a sharp decrease in the surface tension of distilled water, as well as of the oxidized and reduced forms of MB, occurs. The observed narrow time interval is associated with the formation of an exclusion zone near the membrane–solution interface, containing dissociated sulfonate groups $\left(\mathrm{S}{\mathrm{O}}_3^{-}\right)$. The value of the time interval depends on the type of aqueous solution. At long soaking of the membrane in solutions, we obtained: for the aqueous solution of Mb⁺ (blue-coloured solution) the STC value eventually increases by about 5%, and for the reduced form of methylene blue MbH⁰-colourless solution, the STC value decreases by 4%. The STC value of the solutions formed during diffusion into the membrane has a significantly lower value compared to the STC of distilled water by 20% for the Mb⁺ form and by 24% for the MbH⁰ form of MB. The presence of the membrane in the aqueous AA solution causes only an increase in the STC value of the solution. Ultimately, for the solution with a concentration of 5 g/L, this increase reached 15% relative to the STC value of the original AA solution. The change in surface tension of the investigated solutions in the presence of the membrane is due to their adsorption onto the membrane surface. Fourier-transform infrared (FTIR) spectroscopy investigation of distilled water, MB, and AA solution diffusion into the membrane across the range (370–7800) cm⁻¹ confirms the process nonlinearity and enables identification of distinct time intervals corresponding to membrane swelling stages. The positions of IR transmission minima for membranes containing water and solution components remain unchanged; only the numerical values of the transmission coefficients vary. Using spectrophotometry, absorption lines of the membrane with adsorbed components of MB and AA solutions were identified in the range of (190–900) nm. The absorption spectra of dried membranes with adsorbed Mb⁺ and AA solutions show a redshift to the IR region for the Nafion with Mb⁺ and a shift to the UV region for the Nafion soaked in an aqueous ascorbic acid solution. A surface tension gradient at the membrane–solution interface can induce concentration-capillary convection in the liquid. Full article

This study investigates the feasibility of adding gold nanoparticles (Au-NPs) to vanadium oxide (V₂O_x) serving the hole transport layer (HTL) material oin polymer solar cells to enhance cell performance. The first part of this study used Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a baseline and optimized the parameters of this HTL material. Then, the V₂O_x was substituted as the HTL material, and its parameters were optimized again. The second part involved incorporating an aqueous solution of gold nanoparticles (Au-NPs) with an average particle size of approximately 80 nm into V₂O_x. Due to the excitation of localized surface plasmon resonance (LSPR) by Au-NPs, the addition of Au-NPs to the V₂O_x layer can enhance the absorption efficiency of the P3HT:PCBM blended film. Therefore, compared with V₂O_x alone, the solar cells with Au-NPs incorporated into the V₂O₅ hole transport layer demonstrate improved power conversion efficiency (PCE). Full article

Conventional synthesis of polycarboxylate superplasticizers (PCEs) typically relies on high-temperature processes, posing challenges for sustainable production. Ethylene glycol monovinyl polyethylene glycol ether (EPEG), characterized by the high reactivity of its vinyloxy double bond, offers a promising sustainable alternative for low-temperature synthesis. This study systematically investigates the aqueous free radical copolymerization of EPEG and acrylic acid, identifying a reaction temperature of 20 °C as the kinetic optimum that achieves a macromonomer conversion rate exceeding 95% under ambient conditions. Through the variation in five key process parameters, a clear “synthesis–structure–property” relationship was established, revealing that the weight-average molecular weight (M_w) acts as the pivotal regulator of performance. High-M_w PCEs exhibited superior initial dispersion driven by strong electrostatic repulsion and high adsorption but suffered from poor slump retention due to the rapid depletion of free polymers. Conversely, low-M_w variants, regulated by chain transfer agent dosage, significantly reduced the pore solution surface tension, thereby enhancing wetting ability and workability retention. The optimal synthesis conditions (20 °C, 4:1 acid-to-ether ratio, 2.5% initiator, 1.5% chain transfer agent) yielded PCEs with an ideal balance between initial dispersion and retention. Furthermore, the synthesis demonstrated excellent process robustness with a broad dosing window (>60 min). These findings provide a vital theoretical basis for the robust and low-temperature industrial production of EPEG-based PCEs for sustainable infrastructure materials. Full article

Thick (900–1500 µm), crack-free lithium manganese oxide (LMO) electrodes with a polyvinylidene fluoride (PVDF)-based polymer electrolyte were prepared using an innovated slurry casting method. The selectivity and intercalation capacity of the thick electrodes of 900–1500 μm were evaluated in aqueous chloride solutions containing main cations in synthetic Salar de Atacama brine using cyclic voltammetry (CV) measurements. The CV data indicated that a high Li⁺ selectivity of Li/Na = 152.7 could be achieved under potentiostatic conditions. With the thickest electrode, while the mass specific intercalation capacity was 6.234 mg per gram of LMO, the area specific capacity was increased by 3–11 folds compared to that for conventional thin electrodes to 0.282 mg per square centimeter. In addition, 82% of capacity was retained over 30 intercalation/dis-intercalation cycles. XRD and electrochemical analyses revealed that both Faradaic diffusion-controlled or battery-like intercalation and Faradaic non-diffusion controlled or pseudocapacitive intercalation contributed to the capacity and selectivity. This work demonstrates a practical technology for thick electrode fabrication that promises to result in a significant reduction in manufacturing and operational costs for lithium extraction from brines. Full article

Pollution of water resources with hazardous substances of anthropogenic origin (e.g., synthetic dyes, heavy metal ions) is currently one of the most important environmental issues, and the development of not only effective and economical but also eco-friendly methods of removing these substances from aqueous solutions is one of the greatest challenges. Among the various separation methods, techniques based on the utilization of different types of polymer membranes have gained increasing interest due to their usually high efficiency, the materials’ stability and reusability, and the possibility of using “green” components for their formation. Recent research efforts have been concentrated, inter alia, on the application of natural polysaccharide polymers (e.g., cellulose, alginates, starch, cyclodextrins) and their derivatives to produce well-performing membranes. Appropriately composed polysaccharide-based membranes under optimal process conditions enable effective separation of dyes, salts, and metal ions (e.g., often with a rejection rates of >95% for dyes and metal ions and <7% for salts). This review concerns the latest developments in the formation and utilization of novel polysaccharide-based membranes for the separation of synthetic dyes and metal ions from aqueous solutions and suspensions, with emphasis on their most important advantages, limitations, and potential impact on the environment and sustainability. Full article

Hot-melt extrusion produces a solid dispersion (SD) containing a poorly water-soluble drug (k) and matrix polymer surfactant (PS), thereby enhancing k’s solubility. When dissolving the SD, the PS is first dissolved, forming micelles. The amorphous form of the solid phase k remains and is further dissolved by micellar solubilization. The goal here is to rigorously derive, on the basis of thermodynamics, a new expression for the change in the standard Gibbs free energy (${∆G}_{\Sigma }^0$). This change serves as a measure for increasing the degree of spontaneity in the dissolution of amorphous k from an SD with a polymeric surfactant relative to the dissolution of the crystalline-form k in an aqueous solution without surfactants (reference state). In the micelle-pseudophase model, it was found that ${∆G}_{\Sigma }^0$ depends on the natural logarithm of the ratio of mole fraction k in the aqueous phase to mole fraction k in the micellar pseudophase. In a simpler model, ${∆G}_{\Sigma }^0$ can be expressed as ln of the solubility ratio of the crystalline and SD forms, assuming that the activity coefficient depends on the process of incorporating k into the micellar particles and that the total amount of surfactants is many times smaller than the water amount, which is acceptable for polymeric surfactants with low values of the critical micellar concentration. Full article

Biodegradable bioplastics have emerged as a promising sustainable alternative to minimize the environmental impact of traditional plastics. Nevertheless, many of them degrade slowly under natural or industrial conditions, raising concerns about their practical biodegradability. This fact is related to the high-order structure of the polymer backbones, i.e., high molar mass and high crystallinity. Research efforts are being devoted to the development of technologies capable of reducing the length of polymer segments by accelerated chain scission, which could help improve biodegradation rates upon disposal of bioplastic products. The objective of this review is to examine the current state of the art of abiotic degradation techniques, physically driven by temperature, mechanical stress, UV/gamma/microwave irradiation, or plasma or dielectric barrier discharge, and chemically induced by ozone, water, or acidic/basic solutions, with the aim of enhancing the subsequent biodegradation of bioplastics in controlled valorization scenarios such as composting and anaerobic digestors. Particular attention is given to pretreatment degradation technologies that modify surface properties to enhance microbial adhesion and enzymatic activity. Technologies such as ozonation and plasma-driven treatments increase surface hydrophilicity and introduce functional groups with oxygen bonds, facilitating subsequent microbial colonization and biodegradation. Irradiation-based techniques directly alter the chemical bonds at the polymer surface, promoting the formation of free radicals, chain scission, and crosslinking, thereby modifying the polymer structure. Pretreatments involving immersion in aqueous solutions may induce solution sorption and diffusion, together with hydrolytic chain breakage in bulk, with a relevant contribution to the ulterior biodegradation performance. By promoting abiotic degradation and increasing the accessibility of biopolymers to microbial systems, these pretreatment strategies can offer effective tools to enhance biodegradation and, therefore, the end-of-life management of bioplastics, supporting the transition toward sustainable cradle-to-cradle pathways within a biocircular economy. Full article

Exposure to Hg²⁺-contaminated water poses severe risks to human health. Porous organic polymers (POPs) are known for removing heavy metals efficiently. However, the rapid and simple preparation of POP with efficient and selective adsorption capacities remains challenging. Herein, an effective strategy for the room-temperature preparation of TpPa-1 via a 1-step Schiff-base reaction of 2,4,6-triformylphloroglucinol (Tp) and p-phenylenediamine (Pa-1) using scandium(III) trifluromethanesulfonate as a catalyst is described. Various approaches were used to characterize TpPa-1, including SEM, TEM, XRD, FT-IR, NMR, BET, and TG analysis. TpPa-1 was applied to adsorb trace Hg²⁺ from aqueous solution, and its adsorption performance was assessed through batch adsorption experiments. The results indicated that over 94% of 100 μg L⁻¹ Hg²⁺ was removed within 90 min, with the isotherm and kinetics conforming to the Freundlich and the pseudo-second-order models, respectively. Combined with XPS analysis, the Hg²⁺ adsorption of TpPa-1 was primarily dominated by chelation, competitive, and electrostatic interactions between the carbonyl groups of TpPa-1 and Hg²⁺. Because of its benefits of facile synthesis, enhanced removal performance, good selectivity, and reusability, the prepared POP material has great potential for Hg²⁺ removal from aqueous solutions. Full article

The removal of water pollutants with high selectivity and efficiency is still a huge challenge owing to the complex composition of contaminated water. The preparation, modification of Pickering emulsion microspheres, and their application in the adsorption and removal of non-steroidal anti-inflammatory drugs (diclofenac) in water were studied. Poly(2-(diethylamino)ethyl methacrylate-divinylbenzene), (P(DEAEMA-DVB)) microspheres were prepared by Pickering emulsion polymerization. The P(DEAEMA-DVB) polymer was modified with glycidyl trimethylammonium chloride (GTAC) and phenyl glycidyl ether (PGE) to prepare the adsorbent poly(quaternized and phenyl-functionalized) (P(QP-DVB)) with a substantial quantity of quaternary ammonium functional groups. The non-steroidal anti-inflammatory drugs in aqueous solution was mainly adsorbed by the anion exchange interaction with quaternary ammonium species. The adsorption kinetics coincided with the pseudo-second-order kinetic model, and the adsorption isotherm conformed to the Langmuir isotherm model. The optimized P(QP-DVB) particles exhibited well-defined spherical morphology and a uniform particle size distribution ranging from 15 to 30 µm. Nitrogen adsorption/desorption characterization revealed a high specific surface area of 674 m² g⁻¹ and a pore size distribution from 2 to 25 nm. In addition, the aforementioned microsphere underwent chemical regeneration and exhibits good reusability, thereby reducing both the economic costs and environmental impacts. Full article

The contamination of water bodies by dye effluents from micro-scale in-house denim laundries remains a significant environmental concern in central México, particularly in the Atoyac River, where conventional treatment methods are not economically viable. This study develops and evaluates Nylon-6/pumice powder (PPw) nonwoven composites as hybrid adsorptive membranes for the removal of methylene blue (MB) from aqueous solutions. Pumice, a locally abundant siliceous mineral, was incorporated into Nylon-6 through melt-compounding and melt-blown fiber processing at 1 wt% and 5 wt% loadings. SEM, XRD, and TGA confirmed even filler distribution, structural stability, and the development of a porous, layered structure. Batch adsorption tests revealed a rapid initial dye adsorption, followed by a slower diffusion-controlled phase, with equilibrium achieved within 15 min for PPw and within 30 min for the composites. The data fitted both Langmuir and Freundlich isotherms, indicating that MB adsorption involved a combined mechanism: monolayer adsorption on uniform silanol/aluminol sites and multilayer physical adsorption at the polymer–mineral interfaces. Higher PPw content increased adsorption capacity (q_max = 1.1460 mg/g) and surface uniformity, resulting in favorable Freundlich exponents (n = 2). Finally, it was found that adsorption proceeds via chemisorption, where the pumice powder provides reactive sites. These findings demonstrate that Nylon-6/PPw nonwoven composites combine the strength of a synthetic material with the surface reactivity of a natural mineral, providing an effective and scalable Nature-Based Solution for decentralized dye removal, aligned with Sustainable Development Goals 6 and 12. Full article

This study investigates the formation, physicochemical properties, and interfacial behavior of interpolyelectrolyte complexes (IPECs) composed of chitosan (CS) and sodium alginate (ALG) in aqueous media at pH 4.5. Using a combination of turbidity, ζ-potential, conductivity, and interfacial tension measurements, we explore how mixing protocols and solution composition influence complex formation and stability. The results reveal that while ζ-potential remains largely unaffected by polymer concentration, turbidity and interfacial tension exhibit strong dependence, particularly near the stoichiometric charge equivalence point (Z ≈ 1). These findings suggest that neutral complexes formed at Z ≈ 1 display enhanced aggregation and surface activity, especially when ALG is in excess. Additionally, we extend the study to layer-by-layer (LbL) films assembled from CS and ALG, monitored via Quartz Crystal Microbalance with dissipation (QCM-D). The films exhibit quasi-linear growth and increasing elastic modulus with layer number, indicating uniform deposition and strong interlayer interactions. The viscoelastic properties of the multilayers further confirm the structural integrity and potential applicability of these systems in surface engineering and encapsulation technologies. Overall, this work provides a comprehensive understanding of CS–ALG complexation from bulk to interfacial assemblies. Full article

Choline salts represent sustainable and safe electrolyte systems. In this study, an aqueous 1 M choline nitrate solution was employed to prepare hydrogel polymer electrolytes (HPE) via in situ photopolymerization. To enhance compatibility between the electrolyte and polymer matrix, choline methacrylate was synthesized and used as a functional monomer alongside HEMA and PEGDA. The photocurable formulation contained 70 wt.% electrolyte and 30 wt.% monomer mixture. Subsequent electrolyte uptake increased the electrolyte fraction in the HPE to 87 wt.%. The use of choline methacrylate enabled the formation of transparent HPE with favorable mechanical performance, showing puncture resistance of 0.33 N and 0.28 N at elongations of 7.9 mm and 4.4 mm for samples with 70 and 87 wt.% electrolyte, respectively. High ionic conductivity was achieved, reaching ~18 mS/cm and ~34 mS/cm for HPE with 70 and 87 wt.% electrolyte. Finally, a capacitor assembled with HPE containing 87 wt.% electrolyte demonstrated good operational parameters, confirming the applicability of this system in energy storage devices. This work highlights the potential of choline-based electrolytes and polymerizable choline derivatives as functional components for the design of efficient, safe, and environmentally friendly gel polymer electrolytes. Full article

Hydroxy-functional poly(propenyl ether)s are promising thermoresponsive materials; here we establish a controlled synthesis via living cationic polymerization of silyl-protected monomers. Among the silyl protecting groups examined, only tert-butyldiphenylsilyl (TBDPS) enabled living cationic polymerization. The living cationic polymerization of tert-butyldiphenylsiloxybutyl propenyl ether (TBDPSBPE) afforded a high-molecular-weight polymer (poly(TBDPSBPE)) with a narrow molecular weight distribution (M_n = 12,900; M_w/M_n = 1.22). Additionally, chain propagation continued in monomer addition experiments, and the molecular weight increased further with a narrow molecular weight distribution, confirming the success of living cationic polymerization. Poly(TBDPSBPE) was successfully desilylated to afford poly(HBPE) with a narrow molecular weight distribution. Poly(HBPE) exhibited a glass transition temperature (T_g) of 44 °C, 82 °C higher than that of the corresponding polymer without β-methyl groups, poly(HBVE). The enhanced thermal properties of poly(HBPE) were attributed to the steric hindrance of the β-methyl group, which fixes the position of the hydroxy group and allows stronger hydrogen bonding. To investigate the aqueous thermoresponse, a hydroxylated analog with a shorter side-chain spacer (poly(HPPE)) was synthesized, and poly(HPPE) exhibited lower critical solution temperature (LCST)-type phase separation in water with a cloud-point temperature (T_cp) of 6 °C, showing reversible transitions with thermal hysteresis. Full article

Footwear is traditionally manufactured using non-biodegradable polymers and leather, raising well-documented environmental and health concerns related to their production and disposal. This study explores polyhydroxyalkanoates (PHAs) as sustainable alternatives for bio-based footwear components. A stable aqueous suspension of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) was successfully formulated and applied to cotton fabrics via knife-coating. Various formulations, with and without additives and employing natural or synthetic thickeners, were evaluated in terms of surface morphology, wettability, permeability, and durability. The 10% PHBHHx formulation provided the best balance between material efficiency, coating uniformity, and surface performance. Additives and thermal treatment both influenced wettability, reducing contact angles and enhancing water vapor permeability. Notably, coatings with additives and hot pressing exhibited the highest permeability (68.0 ± 3.1 L/m²/s; 651.0 ± 5.4 g/m²/24 h), while additive-free, non-pressed coatings showed significantly lower values (19.5 ± 4.4 L/m²/s; 245.6 ± 66.2 g/m²/24 h), likely due to excessive compaction. Abrasion resistance remained excellent across all samples, especially with thermal treatment, withstanding 51,200 cycles. Washing resistance results revealed a synergistic effect between additives and heat, promoting long-term hydrophobicity and coating adhesion. Overall, PHBHHx coatings demonstrated potential to enhance water resistance while maintaining breathability, representing a sustainable and effective solution for functional and technical footwear applications. Full article