Colloid and Polymer Science最新文献

Environmental pollution with organic dyes is increasing due to the discharge of industrial wastewater. Therefore, introducing an efficient adsorbent for removing organic dyes is of great value. For this purpose, a novel reusable nanocomposite hydrogel (NCH) was synthesized with high adsorption properties. This was achieved by in situ formation of ZnO nanoparticles within the κ-carrageenan/talc-g-poly (acrylic acid) hydrogel network. The resulting nanocomposite hydrogel was then applied as an effective adsorbent for removing cationic dyes from wastewater. The NCH was extensively characterized using techniques such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) analysis. The effect of pH, contact time, temperature, and dye concentration on adsorption efficiency were evaluated. The removal efficiency of crystal violet (CV) was found to be more than 98% at a concentration of 10 mg/L and pH = 6. Under optimum conditions, the maximum adsorption capacity of the NCH for CV was 350 mg/g. The adsorption isotherm follows the Temkin model. The kinetic studies demonstrated that dye adsorption follows the pseudo-second-order model. The adsorption mechanism involves strong electrostatic interactions between the anionic carboxylate groups present in the NCH and the cationic groups of the CV molecule. Additionally, the increased surface area is provided by the incorporation of ZnO nanoparticles. The thermodynamics of adsorption indicated that the adsorption is spontaneous and exothermic in nature. The reusability study indicated that about 93% of initial adsorption capacity was retained after 10 cycles. Therefore, these environmentally friendly nanocomposite hydrogels exhibit outstanding performance in the treatment of dye-contaminated wastewater.

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Since the last 50 years, PVA has been viewed as a versatile material. PVA is gaining attention due to its exceptional film forming properties, biodegradability, and chemical resistance. In the past few years, modified PVA and its composites have been explored because of their improved mechanical, optical and electrical properties. This review is a comprehensive study of PVA-based sensing materials, with a focus on recent advancements in both pristine and composite derivatives. This review is intended to explore their potential applications in emerging fields such as sensing and electrical conductivity. The development of PVA-based sensors is discussed through the review of traditional methods for functionalization of PVA, such as esterification, carbonation, and etherification. Other approaches for the development of PVA-based sensors have also been discussed, such as the preparation of composites, nanocomposites, and blends of PVA. The analysis of polymer samples can be done using a variety of characterization techniques. These include Fourier transformed infra-red spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR), UV visible spectroscopy, gel permeation chromatography (GPC), and many more. These techniques aid in determining the molecular structure and composition of the polymer. The molecular weight of the polymer can be determined by GPC. Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) are techniques that can aid in determining the thermal properties of the material. The review is centred around the existing literature on polyvinyl alcohol-based sensors to examine the current trends, shortcomings, and future scope of the field. The insights presented are intended to reveal research gaps that can lead to further innovations in the development of PVA-based sensing materials.

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The desiccation patterns of colloidal drops evaporating on solid surfaces involves multiple physico-chemical processes, mainly including the redistribution of the non-volatile materials ascribed to the moving liquid medium, the phase transition of the drop from liquid to solid, the generated mechanical stresses in the solid phase and the subsequent crack growth. The mechanisms underlying behind each of the sub-processes is not only a research attention, but also the foundation of engineering applications covering from designed manufactured surfaces to medical diagnostic screening. To understand these mechanisms, several driving forces of the redistribution of colloidal materials in the drop are introduced, for instance various types of liquid flows in the drop, the inter-particle interaction and the adsorption of colloidal particles onto substrate. One type of phase transition - “coffee ring” formation - is subsequently emphasized and its application in manufactured surfaces is also introduced. In addition, we turn our review focus to the formation mechanisms of the generated stresses in the gelled drop and highlights the observed crack growth by varying the factor of the drop contents and substrate wetting properties. However, theoretical work on the non-uniform crack morphologies linked to the non-uniform drop evaporation and stresses is mostly absent. Nevertheless, the characteristic differences between the crack patterns of bio-fluids from healthy individuals and those from patients are directly obtained through macro-scale observations, which lays the foundation of the application of medical diagnostic screening. However, the achievement of this application still requires more in-depth work to overcome the relied subjective observations of the crack patterns and the sensitivity of the crack growth to the ambient conditions. As a multi-field research topic, the colloidal drop evaporation attracts scientists and engineers from disciplines of bio-chemistry, medical science, physics and other involved subjects.

Photothermally responsive hydrogels with excellent mechanical properties are highly sought after for applications in biomedical engineering, soft actuators, and wearable devices. This work presents a simple and effective strategy to construct such hydrogels with enhanced mechanical and photothermal performance by incorporating polydopamine (PDA) and citrate-stabilized gold nanoparticles (Au NPs) via a freeze–thaw process. PDA serves as a broadband photothermal agent, while Au NPs contribute localized surface plasmon resonance (LSPR) effects. Both PDA and Au NPs also act as physical crosslinking points and stress transfer centers within the hydrogel network, and the inclusion of Au NPs further facilitates charge carrier migration, enhancing photothermal conversion. Consequently, compared with pure PVA hydrogels, the PVA@PDA@Au hydrogels exhibited markedly improved photothermal conversion efficiency after three freeze–thaw cycles due to the synergistic interactions among PDA, Au NPs, and the PVA network. In addition, the mechanical properties were significantly enhanced, with the maximum load, tensile strength, and yield stress increasing by 4.6-, 4.2-, and eightfold, respectively.

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Photothermally responsive PVA hydrogels with enhanced photothermal conversion efficiency and mechanical strength were developed via a freeze–thaw process by synergistically incorporating polydopamine (PDA) and citrate-stabilized gold nanoparticles (Au NPs).

Conductivity of water in oil microemulsions as well as reverse micelles of anionic surfactants depends on cations as charge transporters. We first use the versatile molecular system toluene/diethylhexylphosphate H_xNa_1-xDEHP/water to investigate the domains in the phase prism in which four molecular mechanisms of conductivity are identified. The reduced molar conductivity varies over six orders of magnitude. In the regime of “reverse micelles” where all water in the organic phase is bound as the first layer of hydration of head-groups, the dismutation mechanism, discovered by HF Eicke, dominates. In the w/o microemulsion regime, we identify three more conductivity regimes occurring in different regions of the phase diagram. Beyond the dynamic and static percolation, we also identify a more elusive regime: this curvature « frustration » regime is characterized by a decrease in molar conductivity observed upon the addition of water. This anti-percolation regime is due to curved film packing frustration producing an increase of tortuosity. The HDEHP/toluene/water system is the first molecular system for which all four conductivity regimes can be observed at room temperature in different regions of the phase diagram. We also identify the last three conductivity regimes in a microemulsion based on AOT. The single-phase inversion channel, studied as a function of temperature, is limited by Winsor II and Winsor I phase separation. In this domain, the three regimes that can be found are dynamic percolation, anti-percolation as well as static percolation. Therefore, we propose that all four different mechanisms can always be found in ternary w/o microemulsions containing cations as charge carriers.

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In order to solve the shortcomings of existing gel foams, such as poor stability, low strength, and weak water retention capacity, this paper first determined the concentration ranges of the gelling agent and cross-linking agent by referring to other relevant literature and preliminary experiments. Furthermore, the optimal ratio of each component was determined through compounding experiments with foam stabilizers and response surface analysis. Finally, a new high-stability fire-fighting gel foam for mining applications was prepared and its properties were experimentally investigated. The results show that the optimal ratios of gelling agent (CMC), cross-linking agent (aluminum citrate), foam stabilizer (GG:XG = 1:1), and composite foaming agent (SDS:AES = 1:1) of CMC-GG-XG gel foam are: 1.5 ~ 1.6%, 4 ~ 5%, 0.35 ~ 0.4%, and 0.7 ~ 0.8%, respectively. Gel foams prepared outside this ratio range have the problem of not being able to gel or having poor stability after gelation. Compared with ordinary foams and gel foams without adding foam stabilizers, the bubble structure of CMC-GG-XG gel foam changes slowly, and the bubble diameter distribution is concentrated. The water retention rate of CMC-GG-XG gel foam is 26.9% higher than that of gel foam without foam stabilizer when heated at 100 ℃ for 10 h. The viscosity of CMC-GG-XG gel foam changes slowly with temperature, and it can maintain a relatively high viscosity for a long time. CMC-GG-XG gel foam can form a dense three-dimensional network structure and cover the coal surface for a long time. The results of this study support the achievement of stable and efficient fireproof performance of gel foam.

Stimuli-responsive nanocarriers can reduce nonspecific drug release and instead trigger drug release selectively at specific sites or under particular conditions, thereby minimizing side effects and enhancing therapeutic efficacy. In this study, ion pair self-assembly (IPSAM) was developed using poly(allylamine) (PAA) and α-lipoic acid (ALA) through electrostatic interactions between the amino and carboxylic acid groups. The amphiphilic nature of the resulting PAA/ALA ion pairs enabled spontaneous micelle formation in aqueous media. IPSAM(6/4) exhibited the smallest particle size of 94.1 nm, the lowest polydispersity index of 0.155, and the highest zeta potential of 52.06 mV, indicating superior colloidal stability. FT-IR and ¹H-NMR analyses confirmed ion pair formation. Temperature-dependent transmittance measurements showed that the upper critical solution temperature (UCST) of IPSAM(6/4) was approximately 30.7 °C. Surface tension analysis indicated that the IPSAM exhibited amphiphilic characteristics. Reductive responsiveness was verified by treatment with dithiothreitol (DTT), which cleaved the disulfide bond of ALA, converting it to dihydrolipoic acid (DHLA) and inducing structural destabilization. Release experiments showed enhanced drug release in response to both thermal and reductive stimuli, with maximal release observed at 45 °C in the presence of 20 mM DTT. These results suggest that PAA/ALA IPSAM functions as stimuli-responsive nanocarriers and demonstrate potential for targeted drug delivery in reductive and high-temperature environments such as the tumor microenvironment.

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Schematic representation of reduction and temperature responsive IPSAM formed from poly(allylamine) and α-lipoic acid

The current blending polysiloxane softener has not excellent compatibility among molecules with different structures, which leads to an unacceptable modification effect. Regarding this issue, we designed and prepared a nonlinear polysiloxane softener that has the same long-chain, which is relatively free, with traditional polysiloxane softeners, in the hope that it can form effective intermolecular fusion with the latter for an effective and predictable blending modification. This study investigates the tactile characteristics of cotton fabrics treated with linear (SPS) and nonlinear (BPS) polyether-modified polysiloxane softeners. The intermolecular interactions between SPS and BPS were analyzed through thermal properties, particle size distribution, zeta potential, and elemental mapping. The study results demonstrate that molecular entanglement can effectively suppress microphase separation between different compound components, enabling controlled longitudinal distribution of softener components on fiber surfaces. Specifically, the intermolecular interactions between SPS and BPS molecules are clear, and the interaction directly affects the longitudinal distribution tendency of the carbon-ether and silicone-ether segments, which have a large polarity difference, on the cotton fiber surface, thus resulting in different tactile styles. Specially designed in this paper, the entanglement and fusion of softener molecules facilitate uniform longitudinal distribution on the cotton fiber surface, which will contribute to the controlled and predictable tactile properties of cotton textiles. Undoubtedly, this study provides a novel technical approach for the blending modification of traditional polysiloxane softeners.

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In this study, acrylamide (AM), acrylic acid (AA), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and 4-acrylamido-morpholine (ACMO) were used as the raw materials, and the hydrophobic monomer, hexadecyl dimethyl allyl ammonium chloride (DMAAC-C₁₆), and the cross-linking agent poly(ethylene glycol) 200 diacrylate (PEG200DA). A slow-expanding temperature- and salt-resistant polymer nanomicrospheres (PHM) were prepared by reverse-phase microemulsion polymerization. The PHM structure was characterized using infrared spectroscopy, nuclear Magnetic resonance spectroscopy, and scanning electron microscopy, and their properties were analyzed nano-laser particle sizing, and rheometry and employing the filtration factor. The results showed that the average particle size of PHM microspheres was 68.69 nm, and the swelling multiplicity of PHM microspheres was 4.34 times after dissolving in water for four days at 80 ℃. The swelling multiplicity of PHM microspheres after dissolving in mineralized water with a mineralization level of 8 × 10⁴ mg/L for four days at 25 ℃ was 2.34 times, with a blocking rate of more than 85%. The viscoelasticity test showed that the PHM microspheres have good elasticity and good injection performance. Compared with the conventional microspheres (PCM), the introduction of DMAAC-C₁₆ and PEG200DA improves the intermolecular bonding of PHM microspheres as well as the elasticity of the molecular chain, which makes PHM microspheres show excellent performance in temperature and salt resistance, slow expansion and viscoelasticity.

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PHM microsphere initial particle size of 68.69nm, in 80℃ (deionized water) in the expansion of 4 days, the expansion times for 4.34 times; 25℃ (mineralized water) in the expansion of 4 days, the expansion times for 2.34 times, the blocking rate is greater than 85%.

As bacteria are developing stronger resistance, infections caused by Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) are becoming increasingly difficult to treat. Consequently, the preparation of targeted antibacterial hydrogel materials that possess high injectable mechanical strength as well as excellent antibacterial properties has drawn significant attention in the field of antibacterial research. In this paper, Fe₃O₄ particles were used as the magnetic core and shielded by a hydrophilic carbon (C) layer. Subsequently, on the surface of the C layer, a mesoporous polydopamine (MPDA) film with favorable biocompatibility was fabricated, and small-sized Ag nanoparticles (Ag NPs) possessing excellent antibacterial performance were modified thereon. Eventually, the above composite nanoparticles were mixed with pure polyvinyl alcohol (PVA) hydrogel to formulate an injectable antibacterial hydrogel. The antibacterial properties of Fe₃O₄@C@MPDA@Ag nanoparticles at varying concentrations were evaluated through in vitro experiments. The results demonstrated that the higher the concentration of Fe₃O₄@C@MPDA@Ag nanoparticles, the more remarkable the antibacterial effect would be. Moreover, the survival rates of Fe₃O₄@C@MPDA nanoparticles and Fe₃O₄@C@MPDA@Ag nanoparticles on HL-7702 cells were evaluated via in vitro cytotoxicity experiments. The results showed that the two nanoparticles had good biocompatibility. In addition, the antibacterial properties of Fe₃O₄@C@MPDA@Ag@PVA antibacterial hydrogel in mice has been researched. The results indicated that it has good antibacterial properties and wound healing properties.