Interpenetrating Polymer Network Gel Research Articles

Icephobic Coating Based on Epoxy/Polydimethylsiloxane Interpenetrating Polymer Network Gel

Ice accretion endangers the safety and reliability of equipment operation in frigid regions. Silicone polymer icephobic coatings present themselves as an effective strategy. However, they face durability challenges, which is a crucial foundation for expanding their application. In this work, a durable icephobic coating was prepared based on an epoxy/polydimethylsiloxane (PDMS) interpenetrating polymer network (IPN) gel. In the process, epoxy was used to improve mechanical performance. IPN technology was used to integrate PDMS and epoxy. Low-molecular-weight silicone oil was used to adjust the elastic modulus of the coating by reducing crosslinking. The mechanical properties, icephobicity and durability of the coatings were characterized through elastic modulus measurements, ice adhesion strength tests, and icing/deicing cycle tests, respectively. Results shows the ice adhesion strength of the epoxy/PDMS IPN gel coating was approximately 8 kPa when the elastic modulus was 0.18 MPa. Additionally, the epoxy/PDMS IPN gel has good durability, weather resistance, and substrate adhesion. After 25 icing/deicing cycle tests, the coating remained undamaged, and the ice adhesion strength was stable in the range of 3–14 kPa. Within the range of −5 to −30 °C, the ice adhesion strength of the coating was stable and less than 20 kPa. After 168 h of salt spray aging test, the ice adhesion strength of the coating was maintained at 48.72 ± 5.27 kPa. This can provide a reference for an icephobic coating design.

Smart Hydrogel Reactor of Poly(N-isopropylacrylamide)/Polyethylene Glycol Interpenetrating Polymer Networks for Oxidative Coupling of 2-Naphthol

AbstractHydrogels with an interpenetrating polymer network (IPN) structure composed of poly(N-isopropylacrylamide) (poly-NIPAM) gel and a gel containing polyethylene glycol (PEG) chains were synthesized. They showed a typical temperature-responsive volume change in water owing to the constructed poly-NIPAM gel component. Oxidative coupling of 2-naphthol with IPN cryogels and a conventional catalyst, the CuCl2 complex of N,N,N′,N′-tetramethylenediamine, was conducted in water under an O2 atmosphere; the IPN gel prepared from PEG with a larger molecular weight of 11000 afforded a product with a good yield of 73% (91% conv.) during the reaction in basic media. The hydrogel effectively promoted the reaction but hardly produced any product without the catalyst, acting as a reactor vessel in the water. Owing to the low durability of the PEG gel component for hydrolysis, a limitation was also suggested during experiments on the recyclability of the hydrogel.

Preparation and Performance Evaluation of a Plugging Agent with an Interpenetrating Polymer Network.

In view of the problems of polymer cross-linked elastic particle plugging agents commonly used in oilfields, including easy shear, poor temperature resistance, and weak plugging strength for large pores, the introduction of particles with certain rigidity and network structure, and cross-linking with a polymer monomer can improve the structural stability, temperature resistance, and plugging effect, and the preparation method is simple and low-cost. An interpenetrating polymer network (IPN) gel was prepared in a stepwise manner. The conditions of IPN synthesis were optimized. The IPN gel micromorphology was analyzed by SEM and the viscoelasticity, temperature resistance, and plugging performance were also evaluated. The optimal polymerization conditions included a temperature of 60 °C, a monomer concentration of 10.0-15.0%, a cross-linker concentration of 1.0-2.0% of monomer content, and a first network concentration of 20%. The IPN showed good fusion degree with no phase separation, which was the prerequisite for the formation of high-strength IPN, whereas particle aggregates reduced the strength. The IPN had better cross-linking strength and structural stability, with a 20-70% increase in the elastic modulus and a 25% increase in temperature resistance. It showed better plugging ability and erosion resistance, with the plugging rate reaching 98.9%. The stability of the plugging pressure after erosion was 3.8 times that of a conventional PAM-gel plugging agent. The IPN plugging agent improved the structural stability, temperature resistance, and plugging effect of the plugging agent. This paper provides a new method for improving the performance of a plugging agent in an oilfield.

Rational design cold-set interpenetrating network hydrogel based on wheat bran arabinoxylans and pea protein isolates for regulating the release of riboflavin in simulated digestion

Cold-set interpenetrating polymer network gels as riboflavin (RF) delivery vehicles based on wheat bran arabinoxylans (AX) and pea protein isolate (PPI) were developed via enzymatic-crosslinking. The impact of AX concentrations on the physicochemical property, in vitro digestion property and microstructure of IPN gels was explored. Increased concentrations of AX enhanced the viscoelasticity of IPN gels and resulted in a more compact microstructure. However, at a concentration of 5.0 % (w/v), the faster and stronger crosslinking of AX molecules caused separate network gel between PPI and AX. The IPN gel improved the encapsulation efficiency and release property of embedded RF as compared to PPI gel. SEM results showed that IPN gel maintained a complete network structure after gastric digestion. Particularly, the IPN gel with 1.0 % AX exhibited a homogeneous and complete network structure even after intestinal digestion, which explained the reason for the highest encapsulation efficiency and lowest release ratios of RF.

Evaluation of the Accessibility of Molecules in Hydrogels Using a Scale of Spin Probes.

In this work, we explored by means of electron paramagnetic resonance (EPR) spectroscopy the accessibility of a series of spin probes, covering a scale of molecular weights in the range of 200–60,000 Da, in a variety of hydrogels: covalent network, ionotropic, interpenetrating polymer network (IPN) and semi-IPN. The covalent gel network consists of polyethylene or polypropylene chains linked via isocyanate groups with cyclodextrin, and the ionotropic gel is generated by alginate in the presence of Ca2+ ions, whereas semi-IPN and IPN gel networks are generated in a solution of alginate and chitosan by adding crosslinking agents, Ca2+ for alginate and glutaraldehyde for chitosan. It was observed that the size of the diffusing species determines the ability of the gel to uptake them. Low molecular weight compounds can diffuse into the gel, but when the size of the probes increases, the gel cannot uptake them. Spin-labelled Pluronic F127 cannot be encapsulated by any covalent gel, whereas spin-labelled albumin can diffuse in alginate gels and in most of the IPN networks. The EPR spectra also evidenced the specific interactions of spin probes inside hydrogels. The results suggest that EPR spectroscopy can be an alternate method to evaluate the mesh size of gel systems and to provide information on local interactions inside gels.

Interpenetrating polymer network hydrogels of soy protein isolate and sugar beet pectin as a potential carrier for probiotics

In present study, a combination of biopolymers soy protein isolate (SPI) and sugar beet pectin (SBP) has been used to prepare an interpenetrating polymer network (IPN) hydrogel by enzymatic method. The obtained results showed that the rheological properties, textural properties and swelling properties could be tuned by regulating the concentrations of SPI and SBP as well as the amount of laccase. Moreover, the incorporation of probiotic Lactobacillus paracasei LS14 resulted in a decrease of storage modulus (G′) and hardness of SPI/SBP IPN gels. The reason might be that the addition of probiotics caused the exposure of tryptophan-containing extension regions within SPI molecules to a more polar environment. In addition, the occurrence of steric-hindrance effect of probiotic cells during the gelation of IPN hydrogels retarded the formation of covalent cross-links or physical interactions between biopolymer molecules. Scanning electron microscopy (SEM) observation confirmed that the presence of probiotics slightly disrupted the ordered microstructure of the IPN hydrogel. Under simulated gastrointestinal conditions, the SPI/SBP IPN gel showed its advantage in protection of Lb. paracasei LS14 since it had higher viabilities of probiotic cells as compared to free cells. In addition, lyophilized gels exhibited better storage stability but lower probiotic viability in comparison to wet gels. Overall, this study explored a novel method for the production of SPI/SBP IPN gel as a delivery system for probiotics, which would have great potential for development of probiotic-containing foods.

Simultaneous Interpenetrating Polymer Network of Collagen and Hyaluronic Acid as an In Situ-Forming Corneal Defect Filler.

Timely treatment of corneal injuries injury can help to prevent corneal scarring, blindness, and the need for corneal transplantation. This work describes a novel hydrogel that can fill corneal defects and assist in corneal regeneration. This hydrogel is a simultaneous interpenetrating polymer network (IPN) composed of collagen cross-linked via strain-promoted azide-alkyne cycloaddition reaction and hyaluronic acid cross-linked via thiol-ene Michael click reaction. The formation of the IPN gel was confirmed via FTIR spectra, UV-vis spectra, and morphological changes. We compared the gelation time, mechanical properties, transmittance, and refractive index of the IPN gel to the collagen gel, hyaluronic acid gel, and semi-IPN gel. The IPN combined the advantages of collagen and hyaluronic acid gels and supported corneal epithelial cell growth on its surface. When applied to corneal stromal defects in vivo, the IPN avoided epithelial hyperplasia, decreased stromal myofibroblast formation, and increased tight junction formation in the regenerated epithelium.

A self-supported gel filter membrane for dye removal with high anti-fouling and water flux performance

Traditional polymer filtration membranes are easily polluted in operation. An interpenetrating polymer network (IPN) gel was designed as a self-supported filter membrane. This IPN gel was structured by a Ca2+ crosslinked alginate network and a covalently crosslinked poly(acrylamide) network. Polyethylene glycol-polyhedral oligomeric silsesquioxane (PEG-POSS) was hybridised into the gel to optimise performance. Our research demonstrated that the uniform dispersion of PEG-POSS in the matrix improved membrane performance comprehensively due to its nanoscale and amphipathicity. The membranes showed well mechanical properties and sewage treatment capacity. Under the operation pressure 2 bar, the water flux of membranes could keep 11.7 L m−2 h−1 in long-term use. When dealing with the high concentration (500 mg L−1) of Methylene blue and Congo red solution, the rejection of dye could reach 93% and 95% respectively. In anti-fouling experiments with 8000 mg L−1 protein emulsion as the fouling source, the membranes keep over 80% initial flux after 10 times of water-emulsion cycle.

Interpenetrating network gels composed of gelatin and soluble dietary fibers from tomato peels

The advantages of interpenetrating polymer network (IPN) included ideal texture and stability, which was able to apply to the field of food gels. In this study, calcium ions and transglutaminase (TG) were used to cross-link soluble dietary fiber (SDF) from tomato peels and gelatin chains to prepare composite gels with semi-interpenetrating (semi-IPN) or interpenetrating network (IPN) structures. Rheological studies proved that semi-IPN or IPN structures could improve the gelation properties of gels. Scanning electron microscopy showed that the IPN gel had a dense, complex microstructure. In addition, the results of texture property, water-holding capacity, swelling ratio and freeze-thaw stability showed that composite gels had potential to supply specific functional gels, which is good for the development of formula products.

Gelling and bile acid binding properties of gelatin-alginate gels with interpenetrating polymer networks by double cross-linking

Interpenetrating polymer network (IPN) is an effective method to improve functional properties of hydrogels by forming cross-linking networks. In this study, the gelatin-alginate gels formed by the combination of enzymatic and ionic cross-linking were called IPN gels. Meanwhile, the gels with the treatment of only transglutaminase (TG) or Ca2+ were named as G-semi-IPN and A-semi-IPN, respectively. The formation of semi-IPN and IPN was confirmed by studies on rheology, thermodynamics and micro-morphology. The results showed that the IPN gels had improved gelling properties and structural stability. The functional properties of different gelatin-alginate gels were also investigated. It was firstly found that the IPN gels could enhance mechanical properties, decrease swelling capacity and had better bile acid binding capacity. These results of gelatin-alginate gels provide references and novel prospects of IPN for the application in the field of food industry.

Thermo-responsive gels that absorb moisture and ooze water

The water content of thermo-responsive hydrogels can be drastically altered by small changes in temperature because their polymer chains change from hydrophilic to hydrophobic above their low critical solution temperature (LCST). In general, such smart hydrogels have been utilized in aqueous solutions or in their wet state, and no attempt has been made to determine the phase-transition behavior of the gels in their dried states. Here we demonstrate an application of the thermo-responsive behavior of an interpenetrating polymer network (IPN) gel comprising thermo-responsive poly(N-isopropylacrylamide) and hydrophilic sodium alginate networks in their dried states. The dried IPN gel absorbs considerable moisture from air at temperatures below its LCST and oozes the absorbed moisture as liquid water above its LCST. These phenomena provide energy exchange systems in which moisture from air can be condensed to liquid water using the controllable hydrophilic/hydrophobic properties of thermo-responsive gels with a small temperature change.

Novel composite gels of gelatin and soluble dietary fiber from black bean coats with interpenetrating polymer networks

The soluble dietary fiber (SDF) extracted from black bean coats was used to produce a novel composite gel with gelatin by forming an interpenetrating polymer network (IPN). The gel prepared by the cross-linking of transglutaminase (TG) and Ca2+ was called IPN gel, and the gel prepared only by TG or Ca2+ was named as G-semi-IPN and F-semi-IPN, respectively. The rheology and micro-morphology were observed to confirm the formation of semi-IPN and IPN. The thermodynamic, mechanical and hydration properties of gelatin-SDF composite gels with different cross-linking conditions were determined. It was found that the IPN gel had enhanced mechanical properties, better freeze-thaw stability and lower swelling capacity. Bile acid binding assays showed that both semi-IPNs and IPN had certain ability of binding bile acids. These studies on gelatin-SDF composite gels suggested a new strategy to increase the gelling ability of dietary fibers. In addition, it could improve the utilization of bean coats during the food processing.

Fabrication of Sericin/Agrose Gel Loaded Lysozyme and Its Potential in Wound Dressing Application.

Sericin is a biomaterial resource for its significant biodegradability, biocompatibility, hydrophilicity, and reactivity. Designing a material with superabsorbent, antiseptic, and non-cytotoxic wound dressing properties is advantageous to reduce wound infection and promote wound healing. Herein, we propose an environment-friendly strategy to obtain an interpenetrating polymer network gel through blending sericin and agarose and freeze-drying. The physicochemical characterizations of the sericin/agarose gel including morphology, porosity, swelling behavior, crystallinity, secondary structure, and thermal property were well characterized. Subsequently, the lysozyme loaded sericin/agarose composite gel was successfully prepared by the solution impregnation method. To evaluate the potential of the lysozyme loaded sericin/agarose gel in wound dressing application, we analyzed the lysozyme loading and release, antimicrobial activity, and cytocompatibility of the resulting gel. The results showed the lysozyme loaded composite gel had high porosity, excellent water absorption property, and good antimicrobial activities against Escherichia coli and Staphylococcus aureus. Also, the lysozyme loaded gel showed excellent cytocompatibility on NIH3T3 and HEK293 cells. So, the lysozyme loaded sericin/agarose gel is a potential alternative biomaterial for wound dressing.

Switchable Thermal Responsive Interpenetrated Polymer Network Gels of Poly(N-vinylacetamide) and Poly(N-vinylisobutyramide)

Interpenetrating polymer network gel composed of poly(N-vinylacetamide) and poly(N-vinylisobutyramide) was designed for biomaterial use. Temperature triggered poly(N-vinylisobutylamide) (PNVIBA) moieties demonstrated character reversibility due to hydrophobic-hydrophilic change. In this study, the dynamic adsorption and desorption cycle property was determined by Rhodamine B.

Structure, swelling and mechanical behavior of a cationic full-IPN hydrogel reinforced with modified nanoclay

Despite various applications of hydrogels, they have poor gel strength and low resistance against crack propagation which lead to the limitation of their applications. For overcoming this inherent weakness, the current study has focused on the simultaneous utilization of interpenetrating polymer network (IPN) structure and nanocomposite hydrogels. It is known that IPN and nanocomposite gels can improve gel strength. The combination of IPN and nanocomposite structure was developed in hydrogels for improving gel strength. For this purpose, bentonite was successfully modified with a cationic surfactant, (3-methacrylamidopropyl) trimethyl ammonium chloride (MAPTAC), as intercalate, and characterized by TGA, XRD and FTIR. Then we synthesized a novel full-interpenetrating polymer network (IPN) cationic hydrogel nanocomposite reinforced using the modified bentonite (MBe) nanoplatelets. The effect of MBe content on the chemical structure and mechanical properties was studied by means of XRD, FTIR, tensile and rheological measurements. Additionally, the swelling capacity of hydrogel networks was studied. The highest storage modulus for the swollen IPN nanocomposite hydrogel was obtained at 1 wt% of MBe. A similar trend was also demonstrated for the Young’s modulus of the elastic full-IPN hydrogels as the storage modulus of rheological measurements. Therefore, the optimized network had only 1 wt% MBe nanosheets.

Tough biohydrogels with interpenetrating network structure by bienzymatic crosslinking approach

Enzymatically crosslinked biohydrogels have increasingly attracted attention mainly due to the mildness of this type of reaction. However, their mechanical strength is usually so weak that their applications are limited in the field of medicine. In order to improve their mechanical properties and degradation resistance, bienzymatic crosslinking approach was utilized to prepare biohydrogels of gelatin and chitosan with an interpenetrating polymer network (IPN) structure in this report. First of all, chitosan was grafted with phloretic acid (chitosan-PA) used as a substrate of horseradish peroxidase (HRP). After that, the gelation process of gelatin/chitosan-PA IPN hydrogels was monitored by a rheometer. The results indicated the formation of dual networks: one gelatin network crosslinked by transglutaminase (TG) and another chitosan-PA network crosslinked by HRP in the presence of a low concentration of H2O2. In addition, the mechanical performances of the hydrogels were measured by a universal testing machine. It was found that the mechanical properties of the IPN gels were significantly improved compared with gelatin hydrogel crosslinked by TG. Moreover, the swelling ratio, degradation behavior, and cytocompatibility of the IPN hydrogels were investigated in detail. The preliminary biological evaluation indicated that the IPN hydrogels can support L929 cell adhesion and proliferation. Overall, the gelatin/chitosan IPN hydrogels prepared by bienzymatic crosslinking approach have excellent biocompatibility and mechanical properties. Therefore, dual enzyme-mediated crosslinking of natural polymer hydrogels is promising for the development of tissue engineering scaffolds and wound dressing.

Synthesis and application of ion-imprinted interpenetrating polymer network gel for selective solid phase extraction of Cd2+

In the present work, a new Cd2+-imprinted sorbent with interpenetrating polymer network (IPN) structure has been prepared by free radical/cationic hybrid photopolymerization. The ability of the imprinted gel to adsorb Cd2+ was assessed using a batch adsorption technique. The sorption equilibrium data agreed well with the pseudo-second-order kinetic model and the Freundlich isotherm. The study on thermodynamic parameters suggested that the Cd2+ sorption was a spontaneous, exothermic process with further decrease in the degree of freedom. The adsorption mechanism studied by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) indicated that Cd2+ adsorption was mainly through interactions with the NH, OH, CO and CO groups. In addition, the imprinted gel was examined as a column packing material for solid phase extraction of Cd2+. The imprinted gel showed higher selectivity for Cd2+ in comparison to the non-imprinted gel. Relative selectivity coefficients for Cd2+/Cu2+, Cd2+/Ni2+ and Cd2+/Pb2+ were 7.64, 7.58 and 7.59 respectively. The relative standard deviation of the seven replicate determinations of Cd2+ was 1.7%. With preconcentration of 100mL samples, detection limit of 0.5μg/L was determined. The developed method was successfully applied to the determination of trace Cd2+ in various natural water samples with satisfactory results.

Synthesis and Characterization of Phase Change Thermal Storage Waterborne Styrene-Acrylic Emulsion Coating

Ploy (N-hydroxymethyl acrylamide)/polyethylene glycol (PNHMPA/PEG) interpenetrating polymer network gel was prepared as new form-stable phase change thermal filler, and IPN distribute evenly in the new phase change thermal conversion coating. The polarizing microscope shows that IPN is crystalline, which proves its heat storage capacity. The DSC results indicate that the new PCM conversion coating has a good energy storage capability and an available phase transition temperature. The TG results show that the new coating has good thermal stability, and IPN effect of thermal decomposition is not affected by the coating composition.

Converting water absorbent polymer to alcohol absorbent polymer

In this paper, a commercial water absorbent polymer based on poly (sodium acrylate) (PAANa) was converted to an alcohol absorbent polymer. PAANa collapses in alcoholic swelling media such as ethanol and methanol. In the present paper, first, a full interpenetrating polymer network (IPN) gel was prepared through immersing PAANa hydrogel in a solution containing 2‐acrylamido2‐methyl propane sulfonic acid (AMPS), polyethylene glycol dimetahcrylate and ammonium persulfate. The second network was formed in hydrated PAANa through heating. It was synthesized in two conditions by chemical crosslinker and crosslinker‐free. The IPN was acid treated to investigate the effect of removing Na+ on alcohol absorbency. The synthesized IPN gels have the ability of absorbing up to 21 and 39 g/g ethanol and methanol, respectively. The samples which were synthesized using the chemical crosslinker in the second stage had more alcohol absorbency in comparison with the crosslinker‐free samples. Unexpectedly, acid treatment caused a decrease in alcohol absorbency. The IPN gels were characterized through thermogravimetric analyses (TGA) and dynamic mechanical thermal analysis (DMTA). The DMTA results confirmed the IPN structure of the gels, two distinctive peaks, which can be attributed to PAANa, and poly (AMPS) was observed in tan delta figures. TGA thermograms demonstrated that IPN had lower thermal stability in comparison with the initial PAANa, which can be attributed to higher vulnerability of SO3H group for degradation that reduced initial decomposition temperature. Copyright © 2012 John Wiley & Sons, Ltd.

Synthesis and characterization of electroactive epoxy-based interpenetrating polymer network gel

Epoxy/poly(N-isopropylacrylamide) interpenetrating polymer network gels were prepared by varying the excess amine content in the matrix (0.4–0.6equivalent). All the samples were characterized for mechanical properties and swelling in distilled water. The topography of polymer network was characterized by atomic force microscopy. The 0.5equiv. excess amine sample exhibited optimum properties. Studies on swelling at different pH and electroactivity in different aqueous solution were performed. The bending angle observed during first 1min was 1–5 � at 3–10V and a maximum of 25 � in 5min at 20V for 0.5equiv. excess amine in NaCl solution. Copyright # 2011 John Wiley & Sons, Ltd.