Semi-interpenetrating Polymer Network Research Articles

Irradiation-assisted synthesis of smart hydrogels based on nanomagnetic semi-interpenetrating p(HEMA)/PVP networks for the cleaning of cultural heritage artifacts

Preservation of our cultural and historical heritage as a testimony to our shared past is a responsibility that demands significant attention. One of the most critical and delicate aspects of conserving such treasures is cleaning them safely and effectively. Chemical hydrogels specifically designed for cleaning cultural heritage artifacts allow for the containment and controlled release of water. Based on a generic approach, a smart nanomagnetic hydrogel was developed using a semi-interpenetrating polymer network (semi-IPN) of polyhydroxyethyl methacrylate (p(HEMA)) and polyvinyl pyrrolidone (PVP). Gamma irradiation was employed to perform simultaneous in-situ polymerization, crosslinking, and also immobilization of iron oxide magnetic nanoparticles (MNPs). The chemical and structural characteristics of the nanomagnetic hydrogel were investigated using gel content, equilibrium water content, field-emission scanning electron microscopy, magnetic properties, compressive strength, dehydration kinetics, and adhesion tests. The optimal formula for smart hydrogel was a ratio of monomer to polymer 50:50, a water content of 60 wt.%, a gamma radiation dose of 20 kGy, and 3 wt.% of MNP. Two cotton canvas case studies demonstrate the versatility and effectiveness of the selected hydrogel in removing dirt and confining the water-based cleaning system. It was found that no color leaching occurred during the cleaning process.

Repair of acrylic/glass composites by liquid resin injection and press moulding

This paper presents repair methods for in-situ polymerised acrylic (Elium®)/glass fibre (GF) composites focusing on mode-I fracture toughness recovery. GF/acrylic composites were first subjected to double cantilever beam (DCB) tests to measure their Mode-I fracture toughness. The delaminated samples after DCB tests were repaired and rejoined. Two repair methods were performed: liquid resin injection and press moulding at two different temperatures (130 °C and 160 °C). The repaired samples were subjected to a second set of DCB tests. The fracture behaviours of the four specimen groups (virgin, resin-injected, pressed at 130 °C, and pressed at 160 °C) were evaluated in terms of strain energy release rates (GIC) during crack initiation and propagation. The results showed that specimens repaired by resin injection exhibited the highest GIC values, about 30 % higher than the virgin state, due to the formation of a semi-interpenetrating polymer network (semi-IPN) at the joining interface. Scanning electron microscopy images provided insight into distinctive fracture behaviours for each test group.

An investigation on the mechanical and corrosion protection properties of poly(arylene ether nitrile) reinforced epoxy coating

To follow the current industrial demand, epoxy coatings which feature extraordinary comprehensive properties have been considered as a versatile and promising thermosetting resin for application in various middle and high-end sectors of multitudinous industries. Regrettably, epoxy coatings possess the inherent shortcoming of poor durability to external force and deformation, severely restricting further introjection in various fields. Herein, this study employs poly(arylene ether nitrile) with bisphenol A structure (PENBA) as superior intensifying agent to ameliorate the toughness and corrosion resistance of brittle epoxy coatings. As a linear thermoplastic polymer with satisfying mechanical performances, PENBA serves as epoxy's energy-dissipating medium and forms a semi-interpenetrating polymer network (SIPN) with epoxy matrix, efficiently impeding epoxy's fracture and crack propagation. As a result, the tensile strength, elongation at break, impact strength, and flexural strength of PENBA-modified epoxy possess considerable increments of 214 %, 360 %, 148 %, and 295 % in sequence by contrast with the pristine epoxy. Meanwhile, according to the potentiodynamic polarization analysis, the PENBA with outstanding chemical resistance also significantly promoted the epoxy's corrosion resistance, endowing the epoxy coating with the most positive Ecorr and icorr of −0.453 V and 9.439 × 10−10 A/cm2 when PENBA reached 15 % (mass percent) at the end of entire soaking process.

Impact of Modifications from Potassium Hydroxide on Porous Semi-IPN Hydrogel Properties and Its Application in Cultivation.

This study synthesized and modified a semi-interpenetrating polymer network hydrogel from polyacrylamide, N,N'-dimethylacrylamide, and maleic acid in a potassium hydroxide solution. The chemical composition, interior morphology, thermal properties, mechanical characteristics, and swelling behaviors of the initial hydrogel (SH) and modified hydrogel (SB) in water, salt solutions, and buffer solutions were investigated. Hydrogels were used as phosphate fertilizer (PF) carriers and applied in farming techniques by evaluating their impact on soil properties and the growth of mustard greens. Fourier-transform infrared spectra confirmed the chemical composition of SH, SB, and PF-adsorbed hydrogels. Scanning electron microscopy images revealed that modification increased the largest pore size from 817 to 1513 µm for SH and SB hydrogels, respectively. After modification, the hydrogels had positive changes in the swelling ratio, swelling kinetics, thermal properties, mechanical and rheological properties, PF absorption, and PF release. The modification also increased the maximum amount of PF loaded into the hydrogel from 710.8 mg/g to 770.9 mg/g, while the maximum % release of PF slightly increased from 84.42% to 85.80%. In addition, to evaluate the PF release mechanism and the factors that influence this process, four kinetic models were applied to confirm the best-fit model, which included zero-order, first-order, Higuchi, and Korsmeyer-Peppas. In addition, after six cycles of absorption and release in the soil, the hydrogels retained their original shapes, causing no alkalinization or acidification. At the same time, the moisture content was higher as SB was used. Finally, modifying the hydrogel increased the mustard greens' lifespan from 20 to 32 days. These results showed the potential applications of modified semi-IPN hydrogel materials in cultivation.

Electro-induced biochar-embedded-SIPN hydrogel as discrete bipolar electrodes for selective oxidation and enrichment of trace thallium(Ι)

Electrochemical techniques for thallium (Tl) treatment face a substantial challenge linked to the concentration of Tl(I), hindering the efficient removal and recovery of trace Tl(I) (μg L−1). In response, we synthesized hydrogel particles incorporating biochar (BC) within semi-interpenetrating polymer networks (SIPN), showcasing robust selectivity for Tl(I). These biochar-embedded-SIPN hydrogel particles (BC-SIPN particles), employed as dispersed electrodes, facilitated the targeted oxidation and enrichment of Tl(I) through electro-induction. Research outcomes elucidate the adept mitigation of the “efficiency-dependent concentration” behavior by electro-induced BC-SIPN particles during the reaction process. Under optimized conditions (pH 12, 2 V cm−1, 30 min), Tl(I) removal efficiency surpassed 98 % at an initial concentration of 100 μg L−1. The SIPN structure enhanced particle stability, and after seven cycles of enrichment in a 100 μg L−1 Tl(I) environment, BC-SIPN particles achieved a Tl content of 0.073 %, meeting Tl mineral content standards and promoting the recovery of scarce Tl resources. First-principles calculations underscore the pivotal role of hydrogen bond-electrostatic interactions between TlOH(aq) and particles in driving selective Tl(I) adsorption. Insights from quenching and capture reactions reveal a predominant direct oxidation pathway of Tl(I) to Tl(Ⅲ), complemented by indirect oxidation driven by reactive oxygen species, including OH, O- 2 and 1O2. This study presents an innovative approach for trace Tl(I) wastewater treatment, simultaneously mitigating the “efficiency-dependent concentration” phenomenon, and underscores the transformative potential of electro-induced BC-SIPN hydrogel particles in offering sustainable solutions for Tl(I) removal and resource recovery in environmental stewardship.

Collagen-polyurethane-dextran hydrogels enhance wound healing by inhibiting inflammation and promoting collagen fibrillogenesis.

Diabetic foot ulcers are a serious complication of uncontrolled diabetes, emphasizing the need to develop wound healing strategies that are not only effective but also biocompatible, biodegradable, and safe. We aimed to create biomatrices composed of semi-interpenetrated polymer networks of collagen, polyurethane, and dextran, to enhance the wound healing process. The hydrogels were extensively characterized by various analytical techniques, including analysis of their structure, crystallinity, thermal properties, gelation process, reticulation, degradation, cell proliferation, and healing properties, among others. Semi-interpenetrated hydrogels containing dextran at levels of 10%, 20%, and 30% exhibited porous interconnections between collagen fibers and entrapped dextran granules, with a remarkable crosslinking index of up to 94% promoted by hydrogen bonds. These hydrogels showed significant improvements in mechanical properties, swelling, and resistance to proteolytic and hydrolytic degradation. After 24 h, there was a significant increase in the viability of several cell types, including RAW 264.7 cells, human peripheral blood mononuclear cells, and dermal fibroblasts. In addition, these hydrogels demonstrated an increased release of interleukin-10 and transforming growth factor-beta1 while inhibiting the release of monocyte chemotactic protein-1 and tumor necrosis factor-alpha after 72 h. Furthermore, these hydrogels accelerated the wound healing process in diabetic rats after topical application. Notably, the biomaterial with 20% dextran (D20) facilitated wound closure in only 21 days. These results highlight the potential of the D20 hydrogel, which exhibits physicochemical and biological properties that enhance wound healing by inhibiting inflammation and fibrillogenesis while remaining safe for application to the skin.

Removing Aged Polymer Coatings from Porous Stone Surfaces Using the Gel Cleaning Method

Acrylic polymers were extensively used in past restoration practices, usually as consolidants or protecting agents. Their removal is often required because polymer coatings can improve some decay processes of stone substrates and, after ageing, may generate undesirable materials on the surface of artifacts. Therefore, the removal of old polymer coating from the surface of artifacts has become a common operation in the conservation of cultural heritage. As with other cleaning operations, it is a delicate process that may irreversibly damage the artifacts if not correctly carried out. The main aim of this study was to determine the appropriate cleaning procedure for efficiently removing old acrylic polymers (e.g., Paraloid B-72) from the surface of historical buildings. For this purpose, a polymer was applied to two different porous stone substrates (bio-calcarenite and arenaria stone). The hydrogel cleaning approach was used for the present study, as preliminary results suggested that it is the most promising polymer-removing method. The considered hydrogel (based on a semi-interpenetrating polymer network involving poly(2-hydroxyethyl methacrylate) and polyvinylpyrrolidone) was prepared and characterized using different techniques in order to assess the gel’s properties, including the gel content, equilibrium water content, retention capability, hardness, Young’s modulus, and morphology. After that, the hydrogel was loaded with appropriate amounts of nano-structured emulsions (NSEs) containing a surfactant (EcoSufTM), organic solvents, and H2O, then applied onto the coated surfaces. Moreover, plain EcoSurfTM in a water emulsion (EcoSurf/H2O) was also used to understand the polymer-removing behavior of the surfactant without any organic solvent. A comparative study was carried out on artificially aged and unaged polymer-coated samples to better understand the cleaning effectiveness of the considered emulsions for removing decayed polymer coatings. The experimental results showed that the NSE-loaded hydrogel cleaning method was more effective than other common cleaning procedures (e.g., cellulose pulp method). In fact, only one cleaning step was enough to remove the polymeric material from the stone surfaces without affecting their original properties.

Fabrication of cellulose-collagen based biosorbent as eco-friendly scavengers for uranyl ions

The aim of the present research is to fabricate a biosorbent using agricultural waste for removal of uranium from contaminated water i.e. “waste to wealth” approach. Cellulose extracted from wheat straw was mercerized and a novel semi-interpenetrating polymer network (semi-IPN) was fabricated through graft copolymerization of polyvinyl alcohol onto hybrid mercerized cellulose + collagen backbone. Response surface methodology was used for optimization of different reaction parameters as a function of % grafting (195.1 %) was carried out. Semi-IPN was found to possess higher thermal stability. Adsorption results revealed that the optimum parameters for the elimination of uranium using semi-IPN were: adsorbent dose = 0.15 g, pH = 6.0, contact time = 120 min and initial U (VI) concentration = 100 μg/L. The pseudo-second-order kinetic model gave the best description of the adsorption equilibrium data as the calculated qe value is nearest to the experimental qe for the different initial U(VI) concentrations. Adsorption experiments followed Langmuir isotherm with R2 = 0.999. Furthermore, recyclability and reusability studies showed that the adsorption efficiency of semi-IPN was 82 % after 5 cycles indicating the superior recycling execution of fabricated biosorbent. Thus, the fabricated ecofriendly device can be used effectively for the removal of uranium from contaminated wastewater sources.

Fluorinated semi-interpenetrating polymer networks for enhancing the mechanical performance and storage stability of polymer-bonded explosives by controlling curing and phase separation rates

Herein, the effect of fluoropolymer binders on the properties of polymer-bonded explosives (PBXs) was comprehensively investigated. To this end, fluorinated semi-interpenetrating polymer networks (semi-IPNs) were prepared using different catalyst amounts (denoted as F23-CLF-30-D). The involved curing and phase separation processes were monitored using Fourier-transform infrared spectroscopy, differential scanning calorimetry, a haze meter and a rheometer. Curing rate constant and activation energy were calculated using a theoretical model and numerical method, respectively. Results revealed that owing to its co-continuous micro-phase separation structure, the F23-CLF-30-D3 semi-IPN exhibited considerably higher tensile strength and elongation at break than pure fluororubber F2314 and the F23-CLF-30-D0 semi-IPN because the phase separation and curing rates matched in the initial stage of curing. An arc Brazilian test revealed that F23-CLF-30-D-based composites used as mock materials for PBXs exhibited excellent mechanical performance and storage stability. Thus, the matched curing and phase separation rates play a crucial role during the fabrication of high-performance semi-IPNs; these factors can be feasibly controlled using an appropriate catalyst amount.

Enhanced dye removal using montmorillonite modified with graphene quantum dots in sustainable salep nanocomposite hydrogel

This research investigated the utilization of graphene quantum dot/montmorillonite (GQD/MMT) as an effective nanofiller in a hydrogel composed of salep biopolymer. The semi-IPN hydrogel was synthesized using salep as the substrate, acrylamide (AAm) as the monomer, ammonium persulfate (APS) as an initiator in free radical polymerization, and N,N'-methylenebisacrylamide (MBA) as a cross-linking agent. The hydrogels were applied to remove safranin (SA), methylene blue (MB), crystal violet (CV), methyl green (MG), congo red (CR), and malachite green (MG) dyes from the water. The diverse properties were analyzed using a scanning electron microscope, fourier infrared spectroscopy, mapping, energy dispersive spectroscopy, weighing analysis, X-ray diffraction, and thermal stability analyses. The optimism of the prepared adsorbent in dye absorption was evaluated by measuring the swelling amount, pH impact, adsorbent dosage, and contact time. The adsorption calculations were described using kinetics and isotherm models. The results indicated that the Langmuir isotherm model (R2 = 99.6) and the pseudo-second-order kinetic model (R2 = 99.9) provided the best fit for the absorption process of MB. The presence of additional amounts of GQD/MMT had a reciprocal effect on the adsorption efficiency due to the accumulation of GQD/MMT in the semi-interpenetrating polymer network (semi-IPN (structure. The findings revealed that the samples exhibited high thermal stability, and the absorption process was primarily chemical. Furthermore, the nanocomposite hydrogels demonstrated distinct mechanisms for absorbing anionic dye (CR) and cationic dye (MB). Under optimal conditions, using 7 wt% GQD/MMT at a concentration of 5 ppm, pH = 7, an adsorbent dosage of 50 mg, at room temperature, and a contact time of 90 min, the maximum removal efficiencies were achieved: MB (96.2%), SA (98.2%), MG (86%), CV (99.8%), MG (95.8%), and CR (63.4%). These results highlight the adsorbent's high absorption capacity, rapid removal rate, and reusability, demonstrating its potential as an eco-friendly and cost-effective solution for removing dyes from water.

Modulation of the biocompatibility of collagen/polyelectrolyte semi-IPN hydrogels with Zn-bioMOFs.

In this study, we examined the impact of Zn-bioMOF structures on the physical and chemical characteristics as well as the in vitro biocompatibility of a matrix composed of semi-interpenetrating polymeric networks (semi-IPN) made from collagen and L-tyrosine-based polyelectrolytes. We hydrothermally synthesized L-1, ZIF-8H Zn-bioMOFs, and the Zn-(L-His)2 complex, utilizing L-histidine, a bioactive amino acid, as a ligand. These metal-organic compounds primarily enhance the mechanical properties of the novel composite hydrogels through physical interactions such as hydrogen bonds and dipolar interactions. They also accelerate the gelation process. Composites containing Zn-bioMOFs exhibited greater biocompatibility than the collagen/polyelectrolyte matrix alone, as evidenced by cytotoxicity assays conducted with porcine fibroblasts, human monocytes, and RAW 264.7 cells. Furthermore, the evaluated materials did not exhibit hemolysis. We investigated the influence of Zn-bioMOFs on cell signaling by measuring the levels of crucial cytokines involved in the healing process, such as MCP-1, TGF-β, IL-10, and TNF-α secreted by human monocytes. The composite with Zn(L-His)2 promoted the secretion of MCP-1, TGF-β, and IL-10, while a decrease in TNF-α secretion was observed with the composite containing ZIF-8H. Zn-bioMOFs enhanced certain aspects of the biomedical and physicochemical properties of the composite hydrogels. Although the overall performance of the tested materials did not differ significantly, it is worth noting that the presence of Zn-bioMOFs in biopolymeric hydrogels modulated the metabolic activity of cells important for healing and their cytokine signaling, leading to improved biomedical performance.

Sodium alginate/polyvinyl alcohol semi-interpenetrating hydrogels reinforced with PEG-grafted-graphene oxide

Semi-interpenetrating polymer network (SIPN) hydrogels composed of sodium alginate/poly (vinyl alcohol), reinforced by PEG-grafted-graphene oxide (GO-g-PEG) were prepared by ionic crosslinking of sodium alginate. The impact of grafted PEG molecular weight with two molecular weights, i.e. 400 and 2000 g/mol, and component composition were studied on the morphology, swelling behavior, mechanical and dynamic properties. SEM observation showed fine dispersion and distribution of GO-g-PEG throughout the hydrogel indicating a good interaction of particles with the components. Our results revealed that although incorporating GO-g-PEG increases the water content, it significantly enhances the mechanical properties, i.e. tensile modulus, elongation at break, and fracture toughness with a more pronounced impact at higher PEG molecular weight. As a result, the tensile modulus and the elongation at break increased by 270 % and 28 %, respectively. The SA/PVA SIPN hydrogels reinforced with the GO-g-PEG exhibit a non-linear elastic behavior with a toe at low strains. This behavior is attributed to the unique structural features of SIPN hydrogels and the orientation of GO-g-PEG particles with proper interaction with the components. The small amplitude oscillatory shear was also performed to further study the impact of SA, PVA, and GO-g-PEG compositions on the microstructure of hydrogels.

Achieving 1060mWcm-2 with 0.6mgcm-2 Pt Loading Based on Imidazole-Riched Semi-Interpenetrating Proton Exchange Membrane at High-Temperature Fuel Cells.

Enhancing phosphoric acid (PA) doping in polybenzimidazole (PBI) membranes is crucial for improving the performance of high-temperature proton exchange membrane fuel cells (HT-PEMFCs). However, excessive PA uptake often leads to drawbacks such as PA loss and compromised mechanical properties when surpassing PA capacity of PBI basic functionality. Herein, a new strategy that integrates high PA uptake, mechanical strength, and acid retention is proposed by embedding linear PBI chains into a crosslinked poly(N-vinylimidazole) (PVIm) backbone via in-situ polymerization. The imidazole (Im)-riched semi-interpenetrating polymer network (sIPN) membrane with high-density nitrogen moieties, significantly enhancing the PA doping degree to 380% shows an excellent conductivity (0.108Scm-1 ). Meanwhile, the crosslinking structure in the sIPN membrane ensures adequate mechanical properties, low hydrogen permeability, and a relatively low swelling ratio. As a result, the single cell based on the membrane achieves the highest power density of 1060mWcm-2 with a low Pt loading (0.6mgcm-2 ) up to now and exhibits excellent fuel cell stability.

Smart semi-interpenetrated polymer networks from functional silicones and UV-cured polymethacrylic acid: The role of ionic interactions

In this work, semi-interpenetrated polymer networks (semiIPNs) were developed coupling a supramolecular non-covalent network with a UV-cured one in a poly(dimethylsiloxane) (PDMS)-based elastomer. Ionic driven supramolecular assembly was achieved via acid-base proton transfer reaction by blending amine groups, belonging to the side chains of the PDMS-based polymer, and acidic groups, coming from methacrylic acid. Additionally, the CC double bonds were UV-cured, leading to the formation of the final semiIPNs. Multiple formulations were developed by varying the ionic bond density, namely the amine protonation degree, to study the correlation between the polymer structure and the rheological and self-healing properties. Flow curve analyses confirmed the formation of efficient ionic assemblies upon blending, showing an increase of the Newtonian viscosity of the blends at 25 °C as the ionic bond density increased. Moreover, Fourier-transform infrared spectroscopy evidenced the appearance of the peaks associated to the ammonium carboxylate ions, supporting the achievement of the supramolecular network. Particular attention was given to the study of the effect of environmental moisture on the semiIPNs properties, which was found to highly influence the rheological, the mechanical and the self-healing properties.

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.