Copolymer Hydrogels Research Articles

Structure-based design and screening of hydrogel copolymer/Fe3O4 composite microspheres for magnetic solid phase extraction of bisphenol A from aqueous samples

It is of great significance to monitor bisphenol A (BPA) in the environment because of its potential environmental and health risks. However, the detection of trace or ultratrace BPA in complicated environmental samples is challenging due to the relatively low affinity and poor selectivity of existing adsorbents used in sample pretreatment. Herein, we report a high-affinity, low environment-dependent and strong interference-resistant abiotic affinity ligand, a N-methacryloyl-l-lysine-NH2 (MLys)-based hydrogel copolymer (HP 17) screened from a small focused polymer library engineered by incorporating various combinations and ratios of candidate functional monomers. The selection of these monomers was guided by molecular mechanism between BPA and the ligand-binding pocket of its estrogen receptors. The BPA–HP17 binding is mainly a synergistic effect of π-cation and hydrophobic interactions. The screened HP 17 has high adsorption capacity (349.4 mg/g) for BPA under wide pH (3.0–10.0) and ionic strength (0–150 mM) range. To improve its practicability, a hydrogel copolymer/Fe3O4 composite microspheres (Fe3O4@HP 17) was synthesized and applied for magnetic solid phase extraction–high-performance liquid chromatography (MSPE–HPLC) analysis of BPA in tap water, lake water and industrial effluents. The method shows wide linear range (2.5⁓100 ng/mL), high sensitivity (detection limit of 0.22 ng/mL even without further concentration after desorption), high accuracies (92.6⁓103.0 %) and good precisions (0.57⁓4.53 %), indicating a great potential of this material and method in the detection of trace or ultratrace BPA in complex environmental water samples.

Fabrication of Zinc(II) Mediated Poly(Acrylamide Co Acrylic Acid) Hydrogel with Thixotropic and Tribological Properties.

Hydrogels have emerged as promising candidates for biomedical applications, such as replacing natural articular cartilage, owing to their unique viscoelastic properties. However, sufficient mechanical properties, self-healing ability, and adhesive nature are some issues limiting its application window. Here, a facile one-pot synthesis of dual cross-linked zinc-coordinated copolymer hydrogels is presented. The network structure of the copolymer hydrogels is strategically developed via dynamic and reversible physical cross-linking by Zn2+ ions and simultaneous covalent cross-linking through a covalent cross-linker viz methylene bisacrylamide. Fourier-transform infrared (FTIR), X-ray diffraction (XRD) scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analysis have thoroughly characterized the structure of the synthesized hydrogels. The introduction of Zn2+ offers dynamic and reversible complexation, leading to excellent mechanical properties and self-healing features. Moreover, the percentage of the equilibrium water content of zinc-coordinated copolymer hydrogel samples is comparable with that of natural articular cartilage. The Shear sliding study shows the dominant adhesive behavior of HGel-Zn(NO3)2 sample compared to the parent HGel sample. This facile dual cross-linked hydrogel, HGel-Zn(NO3)2, with a combination of good mechanical properties, efficient self-recovery, adequate water content, and favorable adhesive nature, seems very promising to mimic the articular cartilage.

Reprocessible, Reusable, and Self-Healing Polymeric Adsorbent for Removing Perfluorinated Pollutants

Here, we report a reprocessible, reusable, self-healing, and form-switching polymeric adsorbent for remediating fluorinated pollutants in water. The copolymer hydrogel is designed to contain fluorophilic segments and cationic segments to induce strong binding with perfluorinated pollutants. The sorption performance reveals rapid and quantitative removal of these pollutants, driven by the synergistic effect of fluorophilic and electrostatic interaction. Importantly, a disulfide-containing dynamic crosslinker plays a crucial role in imparting multifunctionality. This enables self-healing by the restoration of crosslinks at the cut surfaces by disulfide exchange reactions and allows for the repeated use of the adsorbent via multiple adsorption–desorption cycles. Furthermore, the adsorbent is reprocessible by cleaving the crosslinks to afford linear copolymers, which can be repolymerized into a hydrogel network on demand. Also, form-switching capability is showcased through the aqueous self-assembly of linear copolymers into a fluorinated micelle, serving as another form of adsorbent for pollutant removal.

Mechanically Adaptable High‐Performance p(SBMA‐MMA) Copolymer Hydrogel with Iron (II/III) Perchlorate for Wearable Thermocell Applications

AbstractQuasi‐solid‐state thermocells (QTECs) show promise as a power source for wearable devices by converting body heat into electricity. While significant progress has been made with p‐type elements for QTECs, challenges remain with their n‐type counterparts. Here, a high‐performance n‐type QTEC element is presented, using a copolymer hydrogel that outperforms conventional p‐type elements. This copolymer hydrogel combines hydrophilic zwitterionic sulfobetaine methacrylate (SBMA) for ionic conduction and hydrophobic methyl methacrylate (MMA) for structural stability. By increasing the MMA content from 35 to 100 wt.%, versatile control is achieved over the hydrogel's elastic modulus (72 kPa to 127.7 MPa) and tensile strength (54 kPa to 6.7 MPa). A high mechanical toughness of 7.2 MJ m−3 is also achieved at 68 wt.% MMA. The mechanically robust and high toughness p(SBMA‐MMA) hydrogel is then immersed in Fe(ClO4)2/3 solutions of different concentrations to evaluate its performance as an n‐type QTEC element. The hydrogel with 0.8 M Fe(ClO4)2/3 exhibits a high ionic Seebeck coefficient of −1.7 mV K−1, a power density of 1.1 mW m−2 K−2, and an elastic modulus of 1.6 MPa, which is similar to that of human skin. Finally, the optimized n‐type p(SBMA‐MMA) hydrogels demonstrate the potential application for wearable devices.

Small dop of comonomer, giant shift of dynamics: α-methyl-regulated viscoelasticity of poly(methacrylamide) hydrogels

α-Methyl groups play significant roles in the regulation of water molecules within both small molecular systems and bio-macromolecular systems. Systematically studying the influence of α-methyl on the dynamics of water molecules within hydrogel systems is therefore worthwhile. In this study, we prepared a series of hydrogen-bonded (H-bonded) hydrogels with varying densities of α-methyl groups by copolymerizing methacrylamide (MAm) with its α-methyl-absent analogue, acrylamide (Am). Introducing a small amount of Am (≤6 mol%) into the polymer chain resulted in significant shifts in the viscoelasticity of the hydrogels. The hydrogels exhibit a “time-temperature-α-methyl equivalence”, meaning that introduction of α-methyl-absent monomer has effects similar to elevating temperature and prolonging observation time on the dynamic properties. Based on low-field nuclear magnetic resonance spectroscopy and Raman scattering, a “hydrophilic defects-assisted H-bonds dissociation” mechanism is proposed, depicting that the α-methyl-absent monomer can disturb the rearrangement of water molecules surrounding the polymer chain and accelerate chain dissociation. These findings enabled the copolymer hydrogels with functions such as fast self-healing and tunable interface adhesion.

Evaluation of Dose-Response Relationship in Novel Extended Release of Targeted Nucleic Acid Nanocarriers to Treat Secondary Cataracts.

Purpose: The present study aimed to determine the dose-response relationship between targeted nanocarriers released from a novel, sustained release formulation and their ability to specifically deplete cells responsible for the development of posterior capsular opacification (PCO) in month-long, dynamic cell cultures. Methods: Injectable, thermosensitive poly(D,L-lactic-co-glycolic acid)-b-poly(ethylene glycol)-b-poly(D,L-lactic-co-glycolic acid) triblock copolymer hydrogels were loaded with either a low or a high dose of doxorubicin-loaded antibody-targeted nanocarriers (G8:3DNA:Dox). Human rhabdomyosarcoma cells, selected for their expression of PCO marker brain-specific angiogenesis inhibitor 1 (BAI1), were kept under dynamic media flow and received either a low or high dose of nanocarriers. Cells were fixed and stained at predetermined time points to evaluate targeted depletion of BAI1+ cells. Results: A lower dose of nanocarriers in hydrogel depleted BAI1+ cells at a slower rate than the higher dose, whereas both reached over 90% BAI1+ cellular nonviability at 28 days. Both treatment groups also significantly lowered the relative abundance of BAI1+ cells in the population compared with the control group. Conclusions: Controlled release of a lower dose of nanocarriers can still achieve therapeutically relevant effects in the prevention of PCO, while avoiding potential secondary effects associated with the administration of a higher dose.

Bionic light-responsive hydrogel actuators with multiple-freedom motions in water environments

Soft actuators with biomimetic behavior have widely been utilized in intelligent robotics and artificial muscles. Herein, tannic acid (TA) non-covalently modified and γ-methacrylic trimethoxysilane (MPS) covalently modified MXene (MPS-TA-MXene) are incorporated into a poly(n-isopropylacrylamide-polyacrylamide) (PNIPAM-PAM) copolymer hydrogel to yield a light-responsive hydrogel nanocomposite, denoted as MNA. TA effectively preserves the surface characteristics of MXene while the double bonds in MPS form covalent bonding between MXene and PNIPAM-PAM copolymer, ensuring uniform dispersion of MPS-TA-MXene in MNA hydrogel. Under exposure to ultraviolet light, the resulting MNA hydrogel actuators with nematode- or starfish-shaped exhibit not only bending capabilities in various directions and angles but also demonstrate remarkable multiple-freedom rolling behavior in water environments due to their volume shrinkage induced by the phase transition of MNA hydrogel. Overall, the proposed simply assembled MNA hydrogel actuators with multiple and continuous bionic motions, distinguishing them from conventional single soft actuators limited to bending in one specific direction or performing a simple singular action of rolling, look promising for use in underwater exploration.

Synthesis of stimuli-responsive copolymeric hydrogels for temperature, reduction and pH-controlled drug delivery

Stimuli-responsive copolymeric hydrogels (CH) are synthesized for controlled drug delivery. Oxidized glycyrrhizic acid is connected to acrylamide through Schiff base reaction, which is then copolymerized with N,N-bis (acryloyl) cystamine and N-isopropylacrylamide by free-radical polymerization for the loading of 5-fluorouracil with a loading efficiency of 96.7 %. The lower critical solution temperature of the CH is 39.14 °C. The N-isopropylacrylamide unit in the CH is sensitive to temperature, endowing the CH with temperature sensitivity. The carboxyl groups of oxidized glycyrrhizic acid can be deprotonated in alkaline solutions, and the electrostatic repulsions between the resultant carboxylate can cause swelling of the CH. The disulfide bond (S–S) of the N,N-bis (acryloyl) cystamine unit can be reduced to sulfhydryl (–SH) by glutathione, and thus the CH is also reduction-sensitive. Therefore, temperature, reduction and pH-controlled delivery of 5-fluorouracil from the CH is achieved. Cytotoxicity assay reveals that the drug-free hydrogels have good biocompatibility while the CH shows high cytotoxicity against human hepatoma SMMC-7721 cells, and the cell viability is only 25 % at the CH concentration of 1 mg mL−1.

Synthesis of sodium alginate / polyvinyl alcohol / polyethylene glycol semi-interpenetrating hydrogel as a draw agent for forward osmosis desalination

Typically, hydrogels are described as three-dimensional networks of hydrophilic polymers that are able to capture a certain mass of water within their structure. Recently, hydrogels have been widely used as drawing agents in forward osmosis (FO) desalination processes. The major aim of this study is to prepare a novel semi-interpenetrating hydrogel by crosslinking sodium alginate (SA) and polyvinyl alcohol (PVA) by using the epichlorohydrin (ECH) crosslinker and polyethylene glycol (PEG) interpenetrated within the hydrogel’s network as a linear polymer. Based on the optimum composition of SA/PVA composite hydrogel obtained from our earlier research, the effect of various percentages of PEG on the response of the hydrogel was investigated. The optimal composition of SA/PVA/PEG hydrogel was characterized by scanning electron microscopy (SEM), compression strength testing, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The morphological and mechanical properties of the SA/PVA/PEG semi-interpenetrating hydrogel were also compared to those of the SA/PVA composite hydrogel. Moreover, the performance of the optimal SA/PVA/PEG hydrogel in a FO batch unit as a drawing agent was investigated based on the optimal operation conditions from our previous experiments. The results showed that the optimal PEG/polymer blend mass ratio was 0.25, which increased the swelling ratio (SR) (%) of the hydrogel from 645.42 (of the neat SA/PVA hydrogel) to 2683. The SA/PVA/PEG semi-interpenetrating hydrogel was superior to the SA/PVA copolymer hydrogel in pore structure and mechanical properties. Additionally, in terms of FO desalination, the achieved water flux by SA/PVA/PEG hydrogel is higher than that accomplished by SA/PVA hydrogel.

Designing silver nanoparticles impregnated acacia and tragacanth gum based copolymeric hydrogels for drug delivery applications

The current study investigates the utilization of gum acacia (GA) & tragacanth gum (TG) for the synthesis of silver nanoparticles (NPs) and their subsequent incorporation into hydrogels for potential applications in drug delivery (DD). Cefoperazone, an antibiotic drug, was encapsulated into hydrogels to enhance their antimicrobial activity. Copolymers were characterized by UV–Vis, TEM, FESEM, AFM, XPS, XRD, FTIR, TGA and DSC techniques. UV–Vis spectroscopy revealed the formation of NPs at a wavelength of 436 nm with an optical density of 2.65. TEM images depicted AgNPs with an average size of 37.29 ± 7.25 nm with their uniform distribution. XRD analysis demonstrated distinct crystalline peaks at 2θ = 38.34o, 43.80o, 64.60o and 77.42o attributed to AgNPs. XPS peaks observed at 368 & 374 eV, corresponding to the 3d5/2 and 3d3/2 modes of silver, respectively, confirmed the incorporation of AgNPs in the polymer matrix. Hydrogels demonstrated pH responsive sustained release of cefoperazone. The diffusion mechanism was non-Fickian and described by the Higuchi kinetic model. In the DPPH assay, copolymers exhibited a 32.36 % inhibition of free radicals, whereas in the F–C reagent assay, antioxidant activity was measured as 22.25 μg equivalent of gallic acid. The copolymers displayed blood compatible nature, as evidenced from haemolysis (2.11 ± 0.03 %) and thrombogenicity (74.71 ± 1.63 %) results. The interactions of copolymer with intestinal membrane attributed to mucoadhesive properties and required detachment force of 55.30 ± 2.80 mN to separate from the biological membrane. Growth of E. coli, P. aeruginosa and S. aureus bacteria was inhibited by copolymers with and without antibiotic drug. These characteristic properties of copolymers make them ideal materials for DD carriers.

High-Sensitivity Conductive Copolymer Hydrogel for Multifunctional Flexible Wearable Sensors Based on Salting-Out after Freeze-Casting Assisted UV-Curing

High-Sensitivity Conductive Copolymer Hydrogel for Multifunctional Flexible Wearable Sensors Based on Salting-Out after Freeze-Casting Assisted UV-Curing

Derivation of copolymer hydrogel from Salvia hispanica mucilage and its utilization in adsorption of Reactive Black-5

Derivation of copolymer hydrogel from Salvia hispanica mucilage and its utilization in adsorption of Reactive Black-5

Functional network copolymeric hydrogels derived from moringa gum: Physiochemical, drug delivery and biomedical properties

The article explores the synthesis of network hydrogels derived from moringa gum (MG) through a grafting reaction with poly (vinylsulfonic acid) and carbopol. These hydrogels are designed for use in drug delivery (DD) and wound hydrogels dressing (HYDR) applications. The copolymers were characterized by FESEM, EDX, AFM, FTIR, 13C NMR, XRD and DSC. Tetracycline release from hydrogel occurred gradually with a non-Fickian diffusion and was best described by the Hixson-Crowell kinetic model in artificial wound fluid. The HYDR demonstrated compatibility with blood, exhibited antioxidant properties and possessed tensile strength, in addition to their mucoadhesive characteristics. The copolymer dressings absorbed approximately 7 g of simulated fluid. The copolymers exhibited significant antioxidant activity, measuring at 84 % free radicals scavenging, during DPPH assay. These dressings demonstrated permeability to H2O and O2,. The hydrogel alone did not reveal antibacterial activities; however, when combined with antibiotic drug tetracycline, the dressings revealed notable antibacterial activities against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. The observed biomedical properties suggested that these hydrogels could serve as promising materials for drug delivery HYDR applications.

A new magnetically separable zwitterionic copolymer hydrogel: Synthesis, characterization, and adsorption studies

In this study, a new magnetic organic–inorganic hydrogel composite was prepared and applied as an adsorbent for the removal of contaminants from aqueous media. The composite was prepared by loading FeCo nanoparticles on a zwitterionic copolymer hydrogel (poly(4-vinylbenzenesulfonate-co-[3-(methacryloylamino) propyl] trimethylammonium chloride), poly(MPTC-co-VBS)). Three composites with different FeCo contents were prepared to find the poly(MPTC-co-SVBS): FeCo ratio that achieves the highest adsorption of reactive yellow 160 (RY160) and Ni2+ ions. The prepared materials were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffractometer (XRD), and vibrating-sample magnetometer (VSM).The characterization results revealed that the FeCo nanoparticles, poly(MPTC-co-SVBS) zwitterionic copolymer hydrogel, and FeCo-zwitterionic copolymer hydrogel composites were successfully prepared. The VSM and SEM analysis showed the ferromagnetic nature and porous structure of the FeCo-zwitterionic copolymer hydrogel composite. According to the XRD and FTIR, the FeCo was partially oxidized to CoFe2O4 during the preparation of the FeCo-zwitterionic copolymer hydrogel composite. The composite with the ratio of 2 wt% of poly(MPTC-co-SVBS) to 1 wt% of FeCo (2ZCPH-1FeCo) achieved the highest removal of both RY160 and Ni2+. The optimum removal of RY160 (92 %) was attained using 0.5 g/L of 2ZCPH-1FeCo at pH 7 after 60 min., while the optimum removal of Ni2+ (92 %) was attained using 1.0 g/L at pH 6.5 after 60 min. The PFO and PSO kinetic models described accurately the adsorption of RY160 and Ni2+,respectively. While the isotherm data of RY160 dye and Ni2+ was best described by Freundlich and Temkin models, respectively. Overall, the new FeCo-zwitterionic copolymer hydrogel composite demonstrated remarkable adsorption efficiency and simple magnetic separation post-treatment which makes it a prime contender for practical application in water treatment.

Preparation and drug delivery of hydrogels based on grafting of methacrylamide (MAAm) / vinylsulphonic acid (VSA) co monomers onto psyllium

Recently, a plethora of advancements have been made in the area of polysaccharide research to improve their properties for human health care. The present research is an attempt to develop hydrogels from through grafting of methacrylamide (MAAm) and vinyl sulphonic acid (VSA) co monomers onto psyllium for use in drug delivery (DD) applications. Copolymer hydrogels were characterized by scanning electron micrographs (SEM), Atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), 13C nuclear magnetic resonance (13C NMR), thermogravimetric analysis (TGA) and differential thermal analysis (DTG). SEM, AFM and XRD revealed heterogeneous morphology of the copolymer hydrogels with surface roughness and amorphous state of polymer chains in copolymer hydrogels due to graft-copolymerization reactions. The appearance of the FTIR bands at 1636.87 (amide-I), 1618.11 cm−1 (amide- II), 1469.58 cm−1 (amide- III) indicated presence of amide and bands at 1167.12 cm−1, 1112.06 cm−1 band (symmetric vibrations of SO3H groups and anti-symmetric & symmetric stretching modes of C–S) presence of VSA. The appearance of bands at 181.801 ppm and 62.053 ppm indicated presence of CO carbon of functional groups poly (MAAm) and −CH2–SO3H of poly (VSA) in copolymer hydrogels. Diffusion of the antibiotic drug vancomycin occurred in sustained manner with a non-Fickian diffusion mechanism. The release profile was best described by Korsmeyar-Peppas kinetic model. The copolymers exhibited biocompatible nature and revealed haemolytic index less than 5 % during polymer-blood interactions. The hydrogel demonstrated mucoadhesive character and required 0.135 ± 0.01 N force to detach from mucous membrane. These properties demonstrated the suitability of copolymer hydrogels for drug delivery applications.

Preparation and characterization of the injectable pH- and temperature-sensitive pentablock hydrogel containing human growth hormone-loaded chitosan nanoparticles via electrospraying

This research investigated the in vivo gelation, biodegradation, and drug release efficiency of a novel injectable sensitive drug delivery system for human growth hormone (HGh). This composite system comprises pH- and temperature-sensitive hydrogel, designated as oligomer serine-b-poly(lactide)-b-poly(ethylene glycol)-b-poly(lactide)-b-oligomer serine (OS-PLA-PEG-PLA-OS) pentablock copolymer, as matrix and electrosprayed HGh-loaded chitosan (HGh@CS) nanoparticles (NPs) as principal material. The proton nuclear magnetic resonance spectrum of the pH- and temperature-sensitive OS-PLA-PEG-PLA-OS pentablock copolymer hydrogel proved that this copolymer was successfully synthesized. The HGh was encapsulated in chitosan (CS) NPs by an electrospraying system in acetic acid with appropriate granulation parameters. The scanning electron microscopy images and size distribution showed that the HGh@CS NPs formed had an average diameter of 366.1 ± 214.5 nm with a discrete spherical shape and dispersed morphology. The sol–gel transition of complex gel based on HGh@CS NPs and OS-PLA-PEG-PLA-OS pentablock hydrogel was investigated at 15 °C and pH 7.8 in the sol state and gelled at 37 °C and pH 7.4, which is suitable for the physiological conditions of the human body. The HGh release experiment of the composite system was performed in an in vivo environment, which demonstrated the ability to release HGh, and underwent biodegradation within 32 days. The findings of the investigation revealed that the distribution of HGh@CS NPs into the hydrogel matrix not only improved the mechanical properties of the gel matrix but also controlled the drug release kinetics into the systematic bloodstream, which ultimately promotes the desired therapeutic body growth depending on the distinct concentration used.

Facile synthesis of an acrylic acid-co-2-acrylamide-2-methylpropanesulfonic acid copolymer / polyvinylpyrrolidone semi-IPN hydrogel with excellent swelling and anti-leakage properties

Water scarcity becomes an increasingly serious problem for humankind due to climate change and population growth, especially the water leakage in arid and semi-arid areas. Hydrogel polymers show increasingly important roles on water resources utilization. A novel hydrogel copolymer, acrylic acid-co-2-acrylamide-2-methylpropanesulfonic acid copolymer / polyvinylpyrrolidone (P(AA-co-AMPS)/PVP) semi-interpenetrating network (semi-IPN) hydrogel, was designed and successfully synthesized via a facile one-pot free radical copolymerization method. The main parameters during the synthesis process were optimized, including relative contents of polymer monomers, cross-linking agent, initiator and neutralization agent. Physical characterizations demonstrate that, P(AA-co-AMPS)/PVP hydrogel shows porous three-dimensional network structure, including a crosslinked network structure in P(AA-co-AMPS) copolymers and their intermolecular hydrogen bonding interactions with linear PVP. The as-synthesized P(AA-co-AMPS)/PVP hydrogel not only can deliver superior water absorbing capability (up to 1689.95 g g−1) and good reswelling performance, but also shows excellent water anti-leakage performance when being composed with red clay, demonstrating its multi-role applications in future sustainable agriculture.

Versatile preparation of jellyfish-inspired color transition hydrogels via polymerization induced supramolecular geletion (PISG)

Supramolecular hydrogels based on host–guest interactions constitute a class of intriguing soft matter and have attracted great attention due to their unique properties, etc. In this study, we successfully synthesized 4-methylene-7-diethylaminocoumarin methacrylate (DEACMMA) monomer and carried out reversible addition-fragmentation chain transfer (RAFT) polymerization using methylated β-cyclodextrin via a host-guest encapsulation mechanism. This process led to the formation of ternary copolymer hydrogel supramolecular photoresponsive hydrogels through polymerization induced supramolecular gelation (PISG). The encapsulation of coumarin monomers by methylated cyclodextrins was confirmed using 2D ROESY NMR and fluorescence spectroscopy. We have carefully analyzed the microstructure of these supramolecular hydrogels by rheological profiles and scanning electron microscopy (SEM). Stimulated by UV light, the copolymers transition from non-luminescence to a bright fluorescent blue color, which is reminiscent of the self-transforming colors observed in jellyfish. The development of photostimuli-responsive hydrogels based on methylated β-cyclodextrin-coated coumarin esters opens new avenues in the fields of smart materials and clinical medicine.

Flexible and thermoresponsive AEMR-pNIPAM/Cs0.33WO3 composite hydrogel film with NIR shielding potential for smart windows and smart curtains

Thermoresponsive flexible smart windows and smart curtains having high near-infrared (NIR) shielding and tuned visible light transmittance are essential for improving the energy efficiency of the buildings. The lower critical solution temperature (LCST) of the cross-linked poly(N-isopropylacrylamide) (pNIPAM) hydrogel film was precisely modified to a desired LCST value at 27.4 °C through the free radical copolymerization with 10 wt% of acrylated epoxidized methyl ricinoleate (AEMR). Cs0.33WO3 as NIR shielding nanoparticles (particle size < 200 nm) were synthesized via high energy ball milling method with AEMR as a surfactant for high NIR shielding efficiency and dispersion—the composite flexible hydrogel films with different wt% (0.3, 0.5,0.7, and 0.9 wt%) of Cs0.33WO3 nanoparticles were fabricated to analyze the NIR shielding efficiency and thermal insulation performance. The copolymeric hydrogel film with 0.7 wt% of Cs0.33WO3 nanoparticles (0.7-CWO) demonstrates a significant reduction in the NIR transmittance (15.0 % to 2.3 %) and variation in visible light transmittance from 73.6 % to 15.7 % while undergoing temperature-induced phase transition. The smart window fabricated with composite hydrogel film exhibits good integral luminous transmittance (Tlum, 380–780 nm, 68.7 %, below LCST) and justifiable solar modulation ability (ΔTsol, 300–2500 nm, 53.6 %). A model house was designed to monitor the indoor temperature difference, and a noticeable variation of 7 °C was observed in the house with and without 0.7-CWO film. Further, the developed composite material showed improvement in flexibility, water resistance, and thermal stability, confirming its usage for energy-saving smart windows or smart curtains.

Tuning Mechanical Characteristics and Permeability of Alginate Hydrogel by Polyvinyl Alcohol and Deep Eutectic Solvent Addition.

Alginate-based hydrogels are widely utilized for various applications, including enzyme immobilization and the development of drug delivery systems, owing to their advantageous characteristics, such as low toxicity, high availability and cost-effectiveness. However, the broad applicability of alginate hydrogels is hindered by their limited mechanical and chemical stability, as well as their poor permeability to hydrophobic molecules. In this study, we addressed the mechanical properties and chemical resistance of alginate hydrogels in a high-pKa environment by the copolymerization of alginate with polyvinyl alcohol (PVA). The addition of PVA resulted in a threefold improvement in the shear modulus of the copolymeric hydrogel, as well as enhanced chemical resistance to (S)-α-methylbenzylamine, a model molecule with a high pKa value. Furthermore, we addressed the permeability challenge by introducing a betaine-propylene glycol deep eutectic solvent (DES) into the PVA-alginate copolymer. This led to an increased permeability for ethyl 3-oxobutanoate, a model molecule used for bioreduction to chiral alcohols. Moreover, the addition of the DES resulted in a notable improvement of the shear modulus of the resulting hydrogel. This dual effect highlights the role of the DES in achieving the desired improvement of the hydrogel as an immobilization carrier.