Semi-interpenetrating Polymer Network Research Articles

Preparation and application of self-healing elastomers and coatings at ambient temperature based on semi-interpenetrating polymer networks

Self-healing coatings materials have a wide application in various fields, but achieving a high self-healing property and efficiency at ambient temperature without any additional power is still a big challenge. In this work, a series of elastomers (named LPU-1/EP) were successfully prepared based on a concept of semi-interpenetrating polymer networks. Linear polyurethane (LPU) is used as the “dynamic flow” component, while, epoxy networks provide the necessary mechanical strength. The formation of semi-interpenetrating polymer networks and dynamic hydrogen bonds are conducive to balance self-healing performance and high mechanical strength of the prepared elastomers from the results of rheological test and surface analysis. The typical sample, i.e., LUP-1/EP-3 elastomer, had the highest tensile strength of 1.43 MPa and outstanding ambient temperature self-healing efficiency. The mechanical strength of self-healing LUP-1/EP-3 elastomer was good, and the biggest loading could be more than 1500 mL water after 5 min of self-healing. The toughness of the broken LUP-1/EP-3 elastomer had a recovery value of 81.8% compared to the intact specimen. Furthermore, the LUP-1/EP self-healing coatings were prepared, and the scratch line of LUP-1/EP-3 coatings turned out to be blurry and eliminated after 96 h of self-healing at 30 °C. Electrochemical measurements indicated that both the intact and self-healing LUP-1/EP-3 coatings had a high corrosion protection effect after 75 d of testing in 3.5 wt.% NaCl solution and their impedance values had the same change tendency. LPU-1/EP-3 conductive coating also had a good self-healing performance from the tests of conductive property.

Highly deformable and strongly magnetic semi-interpenetrating hydrogels based on alginate or cellulose

The effective implementation of many of the applications of magnetic hydrogels requires the development of innovative systems capable of withstanding a substantial load of magnetic particles to ensure exceptional responsiveness, without compromising their reliability and stability. To address this challenge, double-network hydrogels have emerged as a promising foundation, thanks to their extraordinary mechanical deformability and toughness. Here, we report a semi-interpenetrating polymer networks (SIPNs) approach to create diverse magnetic SIPNs hydrogels based on alginate or cellulose, exhibiting remarkable deformability under certain stresses. Achieving strong responsiveness to magnetic fields is a key objective, and this characteristic is realized by the incorporation of highly magnetic iron microparticles at moderately large concentrations into the polymer network. Remarkably, the SIPNs hydrogels developed in this research accommodate high loadings of magnetic particles without significantly compromising their physical properties. This feature is essential for their use in applications that demand robust responsiveness to applied magnetic fields and overall stability, such as a hydrogel luminescent oxygen sensor controlled by magnetic fields that we designed and tested as proof-of-concept. These findings underscore the potential and versatility of magnetic SIPNs hydrogels based on carbohydrate biopolymers as fundamental components in driving the progress of advanced hydrogels for diverse practical implementations.

Development of a polyethyleneimine/poly(N-isopropylacrylamide) semi-IPN hydrogel for use in the temperature-swing adsorption and selective desorption of hydrophobic organic compounds

BackgroundA novel polyethyleneimine/poly(N-isopropylacrylamide) semi-interpenetrating polymer network (PEI/poly(NIPA) semi-IPN) hydrogel was developed as a high-performance adsorbent for use in purifying wastewater containing multiple organic compounds and recovering each organic compound. Thermosensitive poly(NIPA) with a lower critical solution temperature (LCST) of ∼33 °C in water can perform the temperature-swing adsorption, i.e., reversibly adsorb/desorb adsorbates as the temperature varies across the LCST owing to its hydrophilic/hydrophobic transition. In addition, PEI, which is a branched polymer with primary, secondary, and tertiary amine groups, can adsorb acidic adsorbates via acid-base interactions. Thus, the developed hydrogel can adsorb adsorbates via hydrophobic and/or acid-base interactions. MethodsThe PEI/poly(NIPA) semi-IPN hydrogel was prepared by free radical polymerization of NIPA and a cross-linking monomer in an aqueous solution dissolving PEI, and characterized as an adsorbent for hydrophobic organic compounds in aqueous media. FindingsThe removal (water purification) and mutual separation (recovery) of binary components (p-nitrophenol and 4-iodoaniline as model adsorbates) were demonstrated via adsorption at 50°C, followed by two-step desorption at 20°C in water and an aqueous HCl solution. This process was based on the presence or absence of hydrophobic and acid-base interactions.

Poly(amidoxime)/polyzwitterionic semi-interpenetrating network hydrogel with robust salt-shrinkage resistance for enhanced uranium extraction from seawater

Effective uranium extraction from seawater can contribute greatly for meeting the needs of low carbon energy. Extensive studies have been conducted on polyamidoxime-based (PAO-based) adsorbents for their exceptional uranium adsorption capabilities. However, the salt-shrinkage effect severely hinders the extraction of uranium from seawater using traditional PAO-based adsorbents. This study synthesizes a novel semi-interpenetrating polymer network hydrogel, designated as PAO/PMPC-SH, using a free-radical polymerization approach utilizing PAO and zwitterionic poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC). The incorporation of the PMPC component endows the adsorbent with exceptional resistance to salt shrinkage owing to the antipolyelectrolyte effect. This characteristic facilitates the diffusion of uranyl ions within PAO/PMPC-SH, even in a high-salt environment with a salt concentration as high as 25 wt%, thereby exposing the uranium binding sites in the adsorbent. Moreover, PAO/PMPC-SH exhibits exceptional antibacterial activity. After 28 days of test in natural seawater, PAO/PMPC-SH demonstrates a high uranium extraction capacity of 6.26 mg g−1, representing only a 9.14 % decrease compared with the capacity of adsorbing in marine microorganism-removed natural seawater. Overall, the notable performance of PAO/PMPC-SH in uranium extraction highlights its potential as a highly effective adsorbent for uranium extraction from seawater.

Tailoring Plant Cell Growth with Collagen-Starch Biomatrices with Calcium bioMOFs

Biomatrices designed to stimulate the growth of tomato cells were prepared in this study. These biomatrices were composed of collagen-starch (CA) through a system of semi-interpenetrating polymer networks, allowing the inclusion of calcium metal-organic frameworks (MOFs) to facilitate plant metabolic stimulation. BioCaMOFs were prepared under hydrothermal conditions (100°C, 48 h) using Ca(NO3)2 and the essential amino acids L-phenylalanine, L-histidine, and L-tryptophan. A 1 mg of each bioCaMOF was dispersed in the collagen-starch matrix, generating the biomatrices CA-MOFCaF, CA-MOFCaH, and CA-MOFCaT, respectively. Infrared spectroscopy was employed to identify the chemical bonds present in each component of the biomatrices. The results indicated that the CA-MOFCaT biomatrix exhibited increased water swelling capacity (2900 ± 180 %) and the highest crosslinking index (74 ± 4 %). Tomato cells derived from sterile seeds (50,000 cells per biomatrix), both red and green varieties, migrated within the biomatrices, enhancing their metabolic activity. The biomatrices containing bioactive calcium MOFs actively stimulated the metabolism of plant cells for up to 48 hours upon contact. Determining that the biomatrix CA-MOFCaF promotes greater stimulation in green tomato cells, while CA-MOFCaT does so with red tomato cells. Such biomatrices hold promise as effective 3D cultures that promote the metabolism of plant cells and could lead to innovative formulations of biofertilizers.

Anionic starch-based hybrid cryogel-embedded ZnO nanoparticles: tuning the elasticity and pH-functionality of biocomposites with dicarboxylic acid units.

Weakly anionic semi-interpenetrating polymer network (semi-IPN) biocomposites based on starch (ST)-incorporated poly(acrylamide-co-itaconic acid)/ZnO (ST-PAI/ZnO) were synthesized by a simple one-pot method via free radical aqueous polymerization. Hybrid biocomposites exhibited lower equilibrium swelling compared with neat copolymer gel. For both hydrogels and cryogels, swelling followed a decreasing order as copolymer PAI > starch-free PAI/ZnO > ST-PAI/ZnO gels. With the addition of 9% ST and ZnO, the swelling ratio of gels decreased from 898 to 68.3, resulting in a significant increase in elastic modulus. Compared with a fixed amount of ST, biocomposite cryogels exhibited significantly higher modulus than hydrogels. With the addition of 9% ST, the elastic modulus of cryogels reached 22.2 kPa while it was 2.7 kPa for the hydrogels. An equation expressing the effective cross-linking density of semi-IPNs presented by a cubic polynomial as a function of starch was obtained. As pH increased with the presence of dicarboxylic acid units, a gradual increase in swelling occurred at two different pH values. A gradually reproducible swelling change of semi-IPNs was depicted with pH ranging from 2.1 to 11.2. Biocomposite cryogels showed rapid swelling in a buffer solution of pH 11.2 and rapid shrinking in pH 2.1. Salt-induced swelling testing showed that the ability to reduce the degree of swelling and solubility of starch was Br- > Cl- > NO3- > SO42- for anions consistent with the Hofmeister series. Adsorption efficiency for the removal of methyl violet (MV) dye was analyzed using Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherm models. The results confirmed that the Langmuir isotherm and pseudo-second-order model are suitable for describing MV adsorption on semi-IPN biocomposites. The synthesized biocomposites with good swelling/deswelling kinetics in different pH-buffer solutions, high saline absorbency, desirable adsorption efficiency, and acceptable pH-dependent swelling reversibility can be considered as smart hybrid materials for the adsorption of the dye in water purification tasks.

Reusable semi-IPN polymer networks as long-term antibacterial coatings.

The current study aimed to develop a reusable antibacterial coating that can be employed for efficient bacterial killing. We synthesized a water-soluble methacrylamide-based copolymer consisting of cationic and hydrophobic groups and coated it onto a glass surface through the formation of semi-interpenetrating polymer networks (semi-IPN) of aminopropyl triethoxysilane and glutaraldehyde. The coated surface was exposed to Gram-negative and Gram-positive bacteria, where the surface exhibited rapid bacterial killing ability within 5-15 min. The substrates displayed a minimal loss of antibacterial activity even after two water rinse cycles. The coatings were able to kill both the bacterial strains even after 5 weeks, suggesting excellent longevity. The surfaces were stable after repeated wiping cycles with 70% IPA using Kim wipes and 5 min sonication in DI water as no bactericidal activity was lost. Thus, a sustainable antibacterial copolymer coating was developed, and it is stable and reusable against bacterial contamination and could be employed as a long-term antibacterial coating.

Impact of Incorporating Silver Nanoparticles (AgNPs) into Collagen-PU-PEG Hydrogels for Superior Antibacterial Efficacy in Severe Wounds

Wound healing is a complex process often hindered by microbial infections, particularly in severe wounds like diabetic ulcers and burns. Collagen-based hydrogels offer potential solutions but lack mechanical support and antibacterial properties. This study explores the incorporation of silver nanoparticles (AgNPs) into Collagen-Polyethylene Glycol (PEG) hydrogels crosslinked with polyurethane (PU) for enhanced wound healing. The hydrogels, labeled CPEG-Ag, revealed a dense fibrillar structure resulting from an interconnected matrix; they exhibited superabsorbent swelling capacity (up to 2100%), which increased with AgNPs content from 0 to 5 wt.%, with no significant effects on the crosslinking (%). FTIR spectroscopy demonstrated the formation of a semi-interpenetrating polymeric network, chemically linked by urea bonds and physically by hydrogen bond interactions. In vitro cell viability studies showed non-cytotoxic effects on monocytes and fibroblast cells, with the former displaying the best metabolic activity after 48 hours of evaluation, while the latter exhibited high proliferation during the first 24 hours, indicating the safe use of CPEG-Ag hydrogels. The effective antibacterial activity against Gram-negative bacteria, E. coli, was also studied, demonstrating that even low contents of AgNPs are sufficient for significant bacterial inhibition. These results highlight the potential of CPEG-Ag hydrogels for wound dressings, especially in complex wounds, and pave the way for future tissue regeneration applications.

Effect of Linear Polyacrylamide on the Properties of semi–IPN Hydrogels Based on N, N’–Dimethylacrylamide, and Maleic Acid

In this work, the semi–interpenetrating polymer network hydrogels based on Polyacrylamide; N, N’–Dimethylacrylamide, and Maleic acid were synthesized and investigated by changing the content of linear polyacrylamide in the obtained materials. The chemical properties, morphology, swelling behaviors in distilled water, and mechanical properties of the hydrogels were investigated. Fourier transform infrared spectra confirmed the polymerization ability of monomers, scanning electronic microscopy images showed that the pore size could be controlled by the added volume of linear polyacrylamide was in the range of 252.8 ± 5.0 ~ 888.5 ± 3.5 µm. The swelling ratio and the mechanical properties of the hydrogels increased with increasing linear polyacrylamide content. All of the results in this work showed that semi–interpenetrating polymer network hydrogels based on Polyacrylamide; N, N’–Dimethylacrylamide, and Maleic acid had a high swelling ratio, good water retention, thermal properties, and mechanical properties. Potential applications of the obtained hydrogels are in progress.

Removal of cationic dye pollutants from wastewater with HS loaded semi-IPN composites: kinetic and thermodynamic studies.

In this study, methylene blue (MB) pollutant in water was removed using produced hazelnut shell loaded semi-interpenetrating polymer networks (HS loaded semi-IPN) adsorbent. The physical and chemical characterizations of the adsorbents were investigated using TGA, DSC, FT-IR, BET, FE-SEM, and EDX. Experimental parameters such as temperature, swelling, dye concentration, contact time, pH solution, and adsorbent dosage for MB adsorption were thoroughly investigated. It was determined that the HS loaded semi-IPN adsorbent removed 92.1% of MB dye. Subsequently, the adsorption properties between the adsorbent and dye were investigated in detail using several different kinetic, isotherm, and thermodynamic models. As a result of the obtained data, the interaction between adsorbent and dye molecules is discussed. Moreover, studies on the industrial usability of the adsorbent have been carried out, and it has been observed that the adsorbent can be employed even after four cycles.

Highly Robust Conductive Organo-Hydrogels with Powerful Sensing Capabilities Under Large Mechanical Stress.

The low mechanical strength of conductive hydrogels (<1MPa) has been a significant hurdle in their practical application, as they are prone to fracturing under complex conditions, limiting their effectiveness. Here, this work fabricates a strong and tough conductive hierarchical poly(vinyl alcohol) (PEDOT:PSS/PVA) organo-hydrogel (PPS organo-hydrogel) via a facile combining strategy of self-assembly and stretch training. With PVA/PEDOT:PSS microlayers and aligned PVA/PEDOT:PSS nanofibers, PVA and PEDOT:PSS nanocrystalline domains, and semi-interpenetrating polymer networks, PPS organo-hydrogels display outstanding mechanical performances (strength: 54.8MPa, toughness: 153.97MJ m-3 ). Additionally, PPS organo-hydrogels also exhibit powerful sensing capabilities (gauge factor (GF): 983) due to the aligned hierarchical structures and organic liquid phase of DMSO. Notably, with the synergy of such mechanical and sensing properties, organo-hydrogels can even detect objects as light as 1 gram, despite bearing a tensile strength of ≈23MPa. By incorporating these materials into human-machine interfaces, such as controlling artificial arms for grabbing objects and monitoring sport behaviors in soccer training, this work has unlocked a new realm of possibilities for these high-performance hierarchical organo-hydrogels. This approach to designing hierarchical structures has the potential to lead to even more high-performance hydrogels in the future.

Emulsion templating of simultaneously-synthesized interpenetrating polymers with degradable components for hierarchical porosities

Hierarchically porous polymers are of interest for a variety applications including adsorption, catalysis, scaffolds, energy storage, and controlled release. In this work, two simultaneous, mutually exclusive reactions within the external phases of water-in-oil high internal phase emulsions (HIPEs) were used to generate macroporous semi-interpenetrating polymer network (semi-IPN) polyHIPE monoliths. The styrenic copolymer of vinylbenzyl chloride (VBC) and divinylbenzene (DVB) was synthesized using free radical polymerization. The non-crosslinked poly(urethane urea) (PUU), based on a polycaprolactone (PCL) triol, was synthesized using step-growth polymerization. The open-cell, semi-IPN polyHIPEs had densities of ∼0.17 g/cm3, corresponding to porosities of ∼84 %. The semi-IPN polyHIPE with the higher P(VBC-co-DVB) content (75 wt %) exhibited a porous structure typical of polyHIPEs, with an average void diameter of ∼10 μm. The porous structure of the semi-IPN polyHIPE with the lower P(VBC-co-DVB) content (50 wt %) resembled a network of channels. Hierarchical porosities were generated by either etching the flexible PCL-based non-crosslinked PUU to generate mesoporosity or by hypercrosslinking the stiff styrenic copolymer framework to generate microporosity. Etching the semi-IPN polyHIPEs in 3 M NaOH removed most of the PUU. Hypercrosslinking generated microporosity and specific surface areas of 445 and 176 m2/g for 75 and 50 wt % P(VBC-co-DVB), respectively. In the semi-IPNs, the hypercrosslinking process also generated mesoporosity from the removal of some of the PUU.

Biobased Semi-Interpenetrating Polymer Networks of Poly(ε-caprolactone) and Epoxidized Soybean Oil with Nanoscale Morphology, Shape-Memory Effect, and Biocompatibility

Biobased Semi-Interpenetrating Polymer Networks of Poly(ε-caprolactone) and Epoxidized Soybean Oil with Nanoscale Morphology, Shape-Memory Effect, and Biocompatibility

Solid Polymer Electrolytes with Dual Anion Synergy and Twofold Reinforcement Effect for All-Solid-State Lithium Batteries.

Solid polymer electrolytes (SPEs) have emerged as a viable alternative to traditional organic liquid-based electrolytes for high energy density and safer lithium batteries. Poly(ethylene oxide) (PEO)-based SPEs are considered one of the mainstream SPE materials with excellent dissociation ability of lithium salts. However, the inferior ionic conductivity at room temperature and poor dimensional stability at high temperature limit their utilization. In this work, a semi-interpenetrating polymer network (semi-IPN) forming a precursor based on an ionic liquid (IL) monomer and linear PEO chains were introduced into an electrospun poly(acrylonitrile) (PAN) fibrous mat with subsequent thermal-initiated cross-linking. 1,4-Diazabicyclo [2.2.2] octane (DABCO) and 4-(chloromethyl) styrene were used to synthesize the styrenic-DABCO-based IL monomer with bis(trifluoromethane sulfonyl)imide (TFSI-) or bis(fluoromethane sulfonyl)imide (FSI-) as the anion, named as SDTFSI and SDFSI, respectively. Together, the FSI- and TFSI- anions demonstrate a synergistic effect in providing ion-conductive LiF and Li3N-rich inorganic SEI layer with enhanced lithium dendrite suppression ability. The twofold reinforcement effect is achieved collectively from the semi-IPN structure and the three-dimensional (3D) PAN network that help to construct highly efficient and uniform ion transport channels with excellent flexibility, further suppressing the lithium dendrite growth. The SPEs were dimensionally stable even at elevated temperatures of 150 °C. Moreover, the SPEs show an ionic conductivity of 4.4 × 10-4 S cm-1 at 25 °C and 1.81 × 10-3 S cm-1 at 55 °C and a lithium-ion transference number of 0.56. The favorable electrochemical performance of the SPEs was verified by operating LiFePO4/Li and NMC/Li cells.

Konjac glucomannan photocrosslinked hydrogels for in vitro 3D cell culture

Konjac glucomannan (KGM) is an attractive naturally-derived polysaccharide commercially available for use in food industry, but with limited application in tissue engineering (TE) as a standalone polymer. We successfully purified and chemically modified KGM, developing innovative covalently crosslinked, fast-forming and degradable KGM hydrogels with tunable mechanical properties for 3D cell culture. Human dermal fibroblasts embedded in KGM matrices remained viable and metabolically active, supporting its good biocompatibility. We further innovated by grafting a bioactive peptide to KGM backbone applying two different chemical approaches, one of them culminating in the synthesis of a novel pH-responsive KGM derivative. Cells embedded in biofunctionalized KGM hydrogels were able to adhere, spread and establish cell-to-cell interactions, encouraging the formation of a cellular network. This work reports different chemical approaches for targeting the fabrication of bioactive KGM-derived hydrogels for 3D cell culture and compares the biological performance of obtained KGM's covalent and semi-interpenetrating polymer networks (SIPN). These results will pave the way for further exploitation of KGM in TE, where it has been commonly applied as blended scaffold formulations rather than as stable extracellular matrix (ECM)-mimicking materials.

Semi-IPN hydrogels with enhanced performance by layered double hydroxide for selective anionic dye removal

The wastewater from the textile industry not only leads to environmental issues but also damages human life. To remove dyes from wastewater, semi-interpenetrating polymer network (sIPN) hydrogels, with or without layered double hydroxide (LDH), were designed and prepared by the polyvinylpyrrolidone-assisted copolymerization of [2-(methacryloyloxy)ethyl]trimethylammonium chloride and acrylamide. The successful fabrication of sIPN hydrogels was confirmed through Fourier transform infrared and diffraction (XRD) techniques. The optimized samples exhibited outstanding selectivity towards anionic dyes, with adsorption capacity values for methyl orange (MO) exceeding 500 mg g−1. Moreover, the incorporation of LDH significantly improved the fragility issue of pure sIPN hydrogels. The adsorption kinetics and isotherm analyses indicated that the adsorption process of the optimized samples adhered well to the pseudo-second-order kinetic model and Freundlich model, suggesting a strong electrostatic interaction mechanism and multilayered adsorption behavior. Notably, the sIPN hydrogel containing LDH could withstand at least 5 consecutive cycles with a regeneration efficiency of 91.3%. Consequently, it is believed that the developed sIPN hydrogels hold great potential as adsorbent materials for anionic dyes.

Regulating electrostatic phenomena by cationic polymer binder for scalable high-areal-capacity Li battery electrodes

Despite the enormous interest in high-areal-capacity Li battery electrodes, their structural instability and nonuniform charge transfer have plagued practical application. Herein, we present a cationic semi-interpenetrating polymer network (c-IPN) binder strategy, with a focus on the regulation of electrostatic phenomena in electrodes. Compared to conventional neutral linear binders, the c-IPN suppresses solvent-drying-induced crack evolution of electrodes and improves the dispersion state of electrode components owing to its surface charge-driven electrostatic repulsion and mechanical toughness. The c-IPN immobilizes anions of liquid electrolytes inside the electrodes via electrostatic attraction, thereby facilitating Li+ conduction and forming stable cathode–electrolyte interphases. Consequently, the c-IPN enables high-areal-capacity (up to 20 mAh cm–2) cathodes with decent cyclability (capacity retention after 100 cycles = 82%) using commercial slurry-cast electrode fabrication, while fully utilizing the theoretical specific capacity of LiNi0.8Co0.1Mn0.1O2. Further, coupling of the c-IPN cathodes with Li-metal anodes yields double-stacked pouch-type cells with high energy content at 25 °C (376 Wh kgcell−1/1043 Wh Lcell–1, estimated including packaging substances), demonstrating practical viability of the c-IPN binder for scalable high-areal-capacity electrodes.

Preparation of a controlled drug release system from semi-interpenetrating polymeric network hydrogel of NaAlg-g-poly(NaA)/PVP

Preparation of a controlled drug release system from semi-interpenetrating polymeric network hydrogel of NaAlg-g-poly(NaA)/PVP

Capsaicin-based silicone antifouling coating with enhanced interlocking adhesion via SIPN

Silicone-based coatings generally exhibit excellent dynamic fouling release due to their low surface energy and elastic modulus. However, the poor adhesion of these coatings at the interface between the coating and the substrate, as well as deficient static antifouling capabilities, severely deteriorate their antifouling properties over extended periods. Herein, an epoxy-poly(dimethylsiloxane)/capsaicin (EP-PDMS/CAP) coating with highly enhanced interfacial adhesion and remarkable antifouling performances was prepared. The coating adhesion strength of the EP-PDMS/CAP has been improved by more than 5 times compared to a PDMS control coating (from 0.4 MPa to 2.04 MPa) by forming a semi-interpenetrating polymer network (SIPN) structure between the epoxy and PDMS layers. The EP-PDMS/CAP coating achieved the superior antifouling effects in both static and dynamic conditions, the anti-bacterial rate was as high as 96.8 %, and the anti-algal adhesion rate to the green algae Chlorella increased by 95.7 %, due to the synergistic effects of the fouling release performance from the PDMS coating and the fouling prevention of capsaicin. Furthermore, the EP-PDMS/CAP coating was proven to be extremely stable in different treatments such as acid/basic solutions, air oven heating test, and cyclic sand abrasion, showing great potential for anti-biofouling under aggressive conditions. This work provides a promising pathway towards the development of high-performance silicone-based composite coatings for efficient marine anti-biofouling.

Characterization of Stimuli-Responsive Acrylamide/Sodium Methacrylate/Kaolin Semi-Interpenetrating Polymer Network Composite Hydrogels

With the advantages of their self-healing, stimuli-response ability, water sorption capacity and shape memory, hydrogels have been commonly utilized. However, new strategies have been developed to enhance mechanical and thermal properties of hydrogels in addition to increase their water sorption. In this study, stimuli-responsive acrylamide/sodium methacrylate based hydrogels were synthesized with the optimization of sodium methacrylate amount by free radical polymerization. With the incorporation of optimum amount of polyethylene glycol 400 (PEG-400) into the hydrogel network, semi-interpenetrating polymer network (semi-IPN) hydrogels were prepared. With the addition of kaolin, swelling properties of the semi-IPN composite hydrogels were investigated in water under the effect of different pH and temperature. Maximum swelling percent of the semi-IPN composite hydrogels was determined as 24214% at pH 7 and 25 °C. Fourier transform infrared spectroscopy (FTIR) analyses revealed that hydrogel samples were successfully synthesized. Morphological structure of hydrogel samples was examined by scanning electron microscopy (SEM) analyses. Both of the water motion through the hydrogel layered structure and water diffusion into the pores made the semi-IPN composite hydrogel more swollen material compared to the acrylamide/sodium methacrylate based hydrogel.