Interpenetrating Polymer Network Films Research Articles

Real-time visual humidity response films of interpenetrating polymer network based on cholesteric liquid crystal and poly (acrylic acid)

ABSTRACT Humidity sensors play a critical role in diverse fields such as agricultural production, medical equipment, and weather forecasting. However, the majority of existing humidity sensors rely on batteries or are relatively costly to construct. In this study, a simple, efficient, and battery-free visual humidity sensor was developed by combining cholesteric liquid crystal (CLC) with acrylic acid (AA) and subsequently curing it to form an interpenetrating polymer network (IPN) film. The IPN film changes colour with relative humidity (RH). Moreover, it has been confirmed that the film exhibits excellent repeatability, and its performance remains relatively unaffected by temperature fluctuations. Additionally, the relationship between film thickness and response time is explored in this research. Through orthogonal experiments involving various proportions of CLC, the study also scrutinises the influence of each component on the humidity response performance of the IPN films. During the transition from 40% RH to 90% RH, IPN film sample 3 experienced a remarkable redshift of 123.05 nm in the reflected wavelength. As for sample 9, its humidity response demonstrated an outstanding linearity of 0.9986. Consequently, the experimental outcomes provide strong evidence that this IPN film exhibits superior humidity response capabilities and holds considerable promise for practical applications.

A facile method to fabricate thermally stable methacrylate‐terminated oligo(2,6‐dimethyl‐1,4‐phenylene oxide)/benzoxazine thermosetting resins with low dielectric constants and losses at 10 GHz

AbstractPoly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) as a kind of low dielectric polymer has been applied in telecommunications. However, developing PPO based thermosetting resins with good comprehensive properties is highly challenging. Herein, an interpenetrating polymer network (IPN) design strategy for the preparation of methacrylate‐terminated oligo(2,6‐dimethyl‐1,4‐phenylene oxide) (SA9000) based thermosetting resins is presented. Two series of prepolymers are prepared by blending bisphenol A/furfurylamine benzoxazine (B‐f) or bisphenol A/aniline benzoxazine (B‐a) with SA9000. Then the IPN films are fabricated by the programmed temperature rising method with simultaneous polymerization reactions of both SA9000 and benzoxazines. Owing to the intermolecular interactions between SA9000 and benzoxazines, the polymerization peak temperatures of all prepolymers are lower than those of SA9000 and benzoxazines. In comparison with B‐a based films, B‐f/SA9000 films display better miscibility and higher thermal resistances over the entire composition range, due to the strengthened hydrogen bonding and higher cross‐linking density resulting from the presence of furan ring of B‐f. Specifically, B‐f/SA9000 films possess the advantages of low dielectric constants (2.296–2.475) and low‐loss grade dielectric losses (0.00550–0.00683) at 10 GHz. The current work provides a simple and effective path for the fabrication of high‐performance thermosetting PPO resins based on benzoxazine chemistry and IPN structure design.

Preparation and properties of water-responsive films with color controllable based on liquid crystal and poly(ethylene glycol) interpenetrating polymer network

ABSTRACT Stimuli-responsive materials have been extensively studied due to their potential in environmental detection and information encryption. In this work, a water-responsive film based on cholesteric liquid crystal (CLC) and polyethylene glycol (PEG) interpenetrating polymer network (IPN) was designed and prepared. When humidity of the surrounding environment changed, the film can reversibly change colour due to the absorption and desorption of water molecules. Compared with the water-responsive films that have been reported now, the step of alkali treatment was eliminated and the damage of the film structure was avoided. More importantly, the factors affecting performances of the IPN film were investigated in detail. By changing these factors, the water-responsive IPN film with different performances can be obtained, implying the unique advantage of this novel film in performance control. Finally, a patterned water-responsive IPN film was designed and prepared using a photomask, demonstrating the potential applications of the intelligent IPN films in information encryption and environmental detection.

A polymer hybrid film based on poly(vinyl cinnamate) and poly(2-hydroxy ethyl methacrylate) for controlled flurbiprofen release

A crosslinked polymer hybrid film, ipn-poly(vinyl cinnamate-graft-2-hydroxy ethyl methacrylate)-v-poly(ethylene glycol dimethacrylate) was synthesized by UV initiation using poly(vinyl cinnamate) (polyVCi), 2-hydroxy ethyl methacrylate (HEMA) monomer and ethylene glycol dimethacrylate (EGDMA) crosslinker. Benzophenone (Ph2CO), was used as the photoinitiator. The synthesis was optimized by changing the concentration of HEMA, Ph2CO, EGDMA, and UV irradiation time. PolyVCi undergoes photocrosslinking by 2 + 2 photocylo addition while the monomer/crosslinker couple, HEMA/EGDMA, undergoes free radical polymerization and crosslinking to form EGDMA crosslinked polyHEMA. Hence, simultaneous interpenetrating polymer network (IPN) formation occurs. The IPN consists of dual network of photocrosslinked polyVCi and EGDMA crosslinked polyHEMA chains. Grafting of HEMA/EGDMA chains on the polyVCi backbone also occur during network formation. The chemical functionalities present in the polyVCi/polyHEMA/polyEGDMA IPN films obtained were characterized by FTIR and SEM analysis. The contact angle measurements show enhanced wettability of the IPN film compared to polyVCi surface. TGA analysis confirms thermal stability of the films. Swelling behavior of the films examined in water and in ethanol reveals the effects of the chemical natures of polyVCi and polyHEMA as well as that of crosslinking on the hydrophilicity of the film. The films were tested as drug release matrices using flurbiprofen. The drug was loaded into the film matrix during IPN formation under UV irradiation. PolyVCi/polyHEMA/polyEGDMA IPN proved to be a suitable release matrix for flurbiprofen demonstrating controlled release behavior and zero-order release kinetics. The release mechanism was confirmed by its Ritger-Peppas “n” value (1.00 to 1.42), which indicates super case II release.

Development of leftover rice/gelatin interpenetrating polymer network films for food packaging

Abstract Waste biomass can be used as a raw material for food packaging. Different concentrations of gelatin (GEL) were introduced into the leftover rice (LR) system to form an interpenetrating polymer network (IPN) for improving the properties of the films. The structure and morphology of films were evaluated by Fourier transform infrared, scanning electron microscopy, and atomic force microscopy, which showed good compatibility between LR and GEL. The moisture content and oil absorption rate of IPN films were down by 105% and 182%, respectively, which showed better water and oil resistance than the LR film. In addition, increasing GEL concentration led to enhancement in the tensile strength of films from 2.42 to 11.40 MPa. The water contact angle value of the IPN films (117.53°) increased by 147% than the LR film (47.56°). The low haze of IPN films was obtained with the increment of the mutual entanglement of LR and GEL. The 30–50% GEL addition improved the water vapor barrier and thermal stability properties of the IPN films. This study highlights that LR as waste biomass can have a practical application in food packaging.

Development of novel network structures in crosslinked liquid-crystalline polymers

Crosslinked liquid-crystalline polymers (CLCPs) show macroscopic deformation along with a change in molecular order, which is triggered by various stimuli such as heat, electricity, and light. CLCPs containing photochromic moieties are realizable as photoresponsive soft actuators. This review focuses on recent developments in novel network structures of CLCPs: rearrangeable networks and interpenetrating polymer networks (IPNs). CLCPs with dynamic covalent bonds could be reshaped into 3D architectures through the rearrangement of the network topology, in contrast with conventional crosslinked polymers memorizing permanent shapes. The reshaped samples showed various photoinduced motions depending on their initial shapes. Furthermore, amorphous polymers were incorporated into conventional CLCP networks to control mechanical and photoresponsive properties. The sequential formation of CLCP and amorphous polymer networks resulted in IPN films with a homogeneous alignment of mesogens. The elastic moduli of IPN films were controlled through the selection of amorphous components. The incorporation of soft components such as poly(dodecyl methacrylate) and poly(dimethylsiloxane) (PDMS) significantly enhanced the rate of photoinduced bending. These strategies of controlling the network structures of CLCPs could enable the versatile design of photomobile polymer materials as soft actuators with desired architectures and functions. Novel network structures were applied to crosslinked liquid-crystalline polymers (CLCPs) with photomechanical effects to enhance their performance and function. CLCPs with rearrangeable networks could be reshaped into 3D architectures, in contrast with conventional crosslinked polymers memorizing permanent shapes. The reshaped samples showed various photoinduced motions depending on their initial shapes. Furthermore, interpenetrating polymer networks (IPNs) were developed to improve mechanical and photoresponsive properties of CLCPs. These strategies of controlling the network structures of CLCPs could enable the versatile design of photomobile polymer materials as soft actuators.

Interpenetrating polymers networks derived from silylated soybean oil and water soluble polysiloxanes

ABSTRACTA series of interpenetrating polymer networks (IPNs) with different compositions were prepared from emulsions of silylated soybean oil (SilSoy) and hydrophilic polysiloxanes (HPPS). Silylation of the soybean oil was achieved via the “Ene reaction” and the water soluble polysiloxanes were prepared by hydrolysis and condensation polymerization of 3‐aminopropyldiethoxymethylsilane followed by a reaction with ethylene carbonate. Unlike the triglyceride structure of SilSoy, HPPS are water soluble, linear polysiloxanes having a pendant hydroxyl group on every siloxane. Evaporation of the water phase from emulsions of SilSoy in aqueous solutions of HPPS yielded crosslinked IPN films composed of silanols and carbinol condensations that formed stable siloxanes (SiOSi) crosslink linkages as well as hydrolysable silicone‐carbinol (SiOC) linkages. The entangled network that was obtained is characterized by intimate mixing of these incompatible phases with a typical IPN microphase separation. The crosslink density between the dispersed phase and the continuous phase was correlated with the swell‐gel data. The mechanical and thermal properties were also studied and were correlated with the composition and the crosslinks density. These IPNs can be used as convenient environmentally degradable control release systems via the hydrolysis of the SiOC linkages. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47182.

Temperature-Responsive Actuators Fabricated with PVA/PNIPAAm Interpenetrating Polymer Network Bilayers

A series of polymer hydrogel bilayers that show temperature-sensitive deformations were prepared and their temperature-responsive gripping ability was tested. One layer was an interpenetrating polymer network (IPN) of poly(N-isopropylacrylamide) (PNIPAAm) and poly(vinyl alcohol) (PVA), and the other layer was crosslinked PVA. The IPN layer was prepared by absorbing N-isopropylacrylamide monomer solution into the crosslinked PVA film and then polymerizing it by UV irradiation. The structure, swelling properties, and mechanical properties of the IPN and PVA films were investigated. The interpenetration of PNIPAAm appeared to restrict the crystallization of PVA, which affected the swelling and mechanical properties of IPN. The bending deformation of the bilayer fabricated by attaching the IPN and PVA films was observed in 25 °C and 37 °C water. The bending diameter and bending direction could be controlled by combining IPN and PVA films with different degree of crosslinking. The gripping test using starfish-shaped bilayers demonstrated mechanical robustness as well as temperature-sensitivity by lifting and releasing an object much heavier than itself in 25 °C and 37 °C water.

Two-photon actuation of crosslinked liquid-crystalline polymers utilizing energy transfer system

ABSTRACTWe prepared crosslinked azotolane liquid-crystalline polymer (LCP) films doped with a stilbene derivative (two-photon chromophore) utilizing an interpenetrating polymer network (IPN) structure. The IPN films bend toward the light source upon irradiation with femtosecond laser pulses at 600 nm, which can excite the stilbene derivative by two-photon absorption. The bending speed of the IPN films increases with the square of the laser pulse intensity, which is compelling evidence for the two-photon processes.

Interpenetrating polymer networks of liquid-crystalline azobenzene polymers and poly(dimethylsiloxane) as photomobile materials.

We developed photomobile polymer materials with interpenetrating polymer network (IPN) structures composed of crosslinked liquid-crystalline azobenzene polymer (PAzo) and poly(dimethylsiloxane) (PDMS). By introducing PDMS into a PAzo template network, IPN was formed without disturbing the alignment of mesogens in the PAzo network. The films showed macroscopic bending behavior upon irradiation with UV and visible light. Although the IPN film showed a phase separated structure, the bending speed was significantly enhanced compared with the pristine film of PAzo, thanks to the soft nature of PDMS. The present method of preparing IPNs can be a promising approach to combine PAzo with various polymers and enhance the mechanical and photoresponsive properties.

Optimization of microwave assisted Maillard reaction to fabricate and evaluate corn fiber gum-chitosan IPN films

The aim of this study was to optimize and characterize microwave assisted Maillard reaction between corn fiber gum (CFG) and chitosan (CH) using 33 full factorial design. Browning intensity, surface free energy components, mechanical properties, thermal attributes, electrical performance, water vapor permeability (WVP), solvent interaction behavior and antimicrobial activity were evaluated. The Maillard reaction product of CFG:CH showed shear thinning behavior. The enhancement in the dispersive components of surface free energy indicated Maillard reaction created water resistance in the films. The films were mechanically strong and flexible. The physicochemical descriptors reflected Maillard reaction produces strong interpenetrating polymer network (IPN) that leads to production of films resistant to water, acids and alkali. This was also observed in SEM analysis. In addition, the enhancement in zones of inhibition suggested antibacterial activity of Maillard reaction product. Overall, the films (F21) produced via Maillard reaction “in situ” were tough, flexible, water resistant and antimicrobial in nature. Thus, suggested high potential of these IPN films in food and pharmaceuticals.

Photomobile Polymer Materials with Double Network Structures: Crosslinked Azobenzene Liquid-Crystalline Polymer/Methacrylate Composites

We prepared photomobile polymer materials composed of crosslinked azobenzene liquid-crystalline polymers (LCPs) and methacrylates with interpenetrating polymer network (IPN) structures, and explored their photoresponsive behavior. The IPN films exhibited reversible bending upon photoirradiation. In addition, the durability of the IPN films was much higher than that of the pristine crosslinked azobenzene LCP films.

Photomobile Properties of Interpenetrating Polymer Network Films Composed of Azobenzene Liquid Crystalline Polymer and Polymethacrylates

Various fabrication methods of photomobile polymer materials containing photochromic moieties have been developed to improve their photoresponsive and mechanical properties. Here, we newly prepared photomobile polymer materials with interpenetrating polymer network (IPN) structures. The IPN films, which are composed of azobenzene liquid crystalline polymer (LCP) and polymethacrylates, showed reversible bending behavior upon exposure to UV and visible light. Bending speed of the IPN films became higher with decreasing glass-transition temperature of polymethacrylate components. The IPN film containing poly(dodecyl methacrylate) showed faster bending than the pristine azobenzene LCP film.

Morphologies and applied properties of free radical/cationic UV-cured CPUA/TMPTMA/CER composite films

A UV-cured composite film was prepared by free free-radical photopolymerization from a blend containing oligomer cycloaliphatic polyurethane acrylate (CPUA) and reactive diluent trimethylolpropane trimethaacrylate (TMPTMA) with the same weight (coded as UT) in the presence of free free-radical photoinitiator Irgacure 754. It was proved to be a homogeneous system featuring only one phase by means of scanning electron microscopy (SEM). Cycloaliphatic epoxy resin (CER) was introduced to enhance mechanical properties of the UV-cured UT composite film in the presence of cationic photoinitiator Irgacure 250, and a series of UV-cured CPUA/TMPTMA/CER composite films with different component ratios were prepared by free radical/cationic hybrid UV UV-curing technique. Results of conversion curves, SEM, and Fourier- transform infrared spectroscopy illustrated that UT was cured faster than CER, leading to dynamically asymmetric photopolymerization-induced phase -separation behaviors. The thermal and mechanical properties were evaluated via thermal degradation analysis, dynamic mechanical analysis, and stress–strain curves. Surface properties such as pencil hardness, pendulum hardness, shrinkage rate, contact angle, flexibility, and glossiness were also studied. All these measurements revealed that component ratios, intermolecular attractions, photopolymerization velocities, and viscosities had remarkably influenced on the morphologies and applied properties of UV-cured composite films, and interpenetrating polymer network films had better comprehensive performances than other UV-cured composite films with different microstructures. POLYM. COMPOS., 36:1177–1185, 2015. © 2014 Society of Plastics Engineers

Development of novel chitosan-poly(N,N-diethylacrylamide) IPN films for potential wound dressing and biomedical applications

Novel interactive and thermoresponsive interpen- etrating polymer network (IPN) films, which are transparent, permeable to oxygen, and have the potential to be easily stripped from a wound bed, were synthesised using rapid photopolymerisation and crosslinking of DEAAm in the pres- ence of chitosan. This study provides the first evaluation and optimisation of a UV-polymerised chitosan-PDEAAm IPN composite film for application in wound dressings. FTIR spec- troscopy and DSC analysis were used to initially characterise the resulting films. Modulated differential scanning calorimetry results showed that the dressings exhibited lower critical solu- tion temperatures in the desired range, while the samples were also observed to undergo temperature-dependent swelling be- haviour. This thermosensitive property would potentially allow the dressings to be easily detachable, which would enable frequent dressing changes if desired without causing further injury to healing tissues. Furthermore, the water content values recorded are in the typical and desired ranges for commercial wound dressings.

Influence of the poly(ethylene oxide)/polybutadiene IPN morphology on the ionic conductivity of ionic liquid

Solid polymer electrolytes (SPEs) were prepared by incorporating either aqueous LiClO4 or 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI) ionic liquid into Poly(ethylene oxide) (PEO)/polybutadiene (PB) Interpenetrating Polymer Networks (IPNs). With a given PEO/PB ratio, either transparent or translucent films depending on the synthesis route of these IPNs, have been investigated. TEM observations confirm that the morphology of these IPN films depends also on the PEO weight proportion whereas mechanical properties measured by DMA are only slightly modified. Measurements of ionic conductivity of SPEs are also very dependent on the IPNs morphology. For instance, EMITFSI ionic conductivity increases over four orders of magnitude from 2.2×10−7 to 2.5×10−3Scm−1 at 30°C.

Preparation of epoxy/polyelectrolyte IPNs for flexible polyimide-based humidity sensors and their properties

Resistive humidity sensors based on an epoxy interpenetrating polymer network (IPN) polyelectrolyte films, which had strong adhesion to polyimide substrate, were developed for flexible polyimide electrode. Humidity sensitive epoxy IPN films were prepared using two stage cross-linking between the diglycidyl ether of bisphenol-A (DEGEBA) and a phosphate ester curing agent (EPEs), followed by photocuring of copolymer of 2-(cinnamoyloxy)ethyl methacryate (CEMA) and [2-(methacryloyloxy)ethyl] trimethyl ammonium chloride (METAC). Under optimal conditions ([METAC/CEMA]/[DGEBA/EPEs]=2/1), a semi-log graph of film resistance was plotted linearly by four orders of magnitude (from 103 to 107Ω) on increasing humidity over a humidity range of 20–95%RH and exhibited good linearity (Y=−0.0529X+7.8048, R2=−0.9944). Furthermore, reliability testing (in terms of water resistance and high temperature, humidity, and long-term stabilities) of the epoxy IPN/gold electrode/polyimide substrate showed that they are satisfactory for use as flexible humidity sensors.

Patterning of Conducting Polymers Using UV Lithography: The in-Situ Polymerization Approach

We report on the in-situ polymerization of 3T with Cu(ClO4)2 inside several host polymers such as Novolak-based negative-tone photoresist, polystyrene (PS), poly(4-vinylphenol) (P4VP), poly(methyl methacrylate) (PMMA), and poly(4-vinylphenol)-co-(methyl methacrylate) (P4VP-co-MMA) to form an interpenetrating polymer network (IPN). Conducting IPN films in the order of 10–4–150 S/cm are obtained depending on the specific IPN composition. Moreover, the convenience of this synthetic approach has been demonstrated using a commercially available negative-tone photoresist based on Novolak as a host polymer. Novolak photoresist was properly formulated with 3T and Cu(ClO4)2 to preserve as far as possible the negative lithographic characteristics of Novolak-based photoresist and generate conductive micropatterns by means of UV lithography. The CP is in situ synthesized into the Novolak matrix by a postbake after the lithography process (exposure + development). The electrical conductivity of the patterned film is 10–2 S/cm. We accurately patterned three different types of microstructures with different resolutions: interdigitated structures with a width of 100 μm, 200 μm side squares, and a 20 μm wide cross. We believe this synthetic approach is of potential application to modify the conductivity of numerous insulating polymers while preserving their physical and chemical properties.

Preparation and Properties of Interpenetrating Polymer Network Films from Prevulcanized Natural Rubber Latex/Chitosan Blends

The acidfied sulfur-prevulcanized natural rubber (NR) latex was mixed with 1～20 parts per hundred rubber (phr) of a 2wt% solution of chitosan (CS) in 1wt% acetic acid, then cast to preapare a series of NR/CS semi-interpenetrating polymer network (semi-IPN) films; the NR/CS semi-IPN films were further treated with 0.5wt% glutaraldehyde（GA）solution for respectively 1, 3 and 6h to obtain NR/CS IPN films. The mechanical properties and swelling behavours in various media of water, toluene and reference olis of IRM901 and IRM 903 of these films were studied and compared with those pure sulfur-prevulcanized natural rubber latex (SNRL) film. Results showed that, NR/CS IPN films with better mechanical properties could be obained by treating the 24h-leached NR/CS semi-IPN films than by treating directly the unleached ones with 0.5wt% GA solution; the tear strength, 300% modulus, Shore A hardness, hydrophilicity and resistance to non-polar solvents and oil of the SNRL films increased with the incorporation of CS, while the NR/CS IPN films exhibited better than the NR/CS semi-IPN films, especially in tear strength enhancement; the tensile strength and elongation at break of NR/CS semi-IPN and IPN films gradually decreased with the increase in CS content. However, most of the elasticity of pure NR vulcanizate could be reserved, when the CS content was not greater than 15 phr.

Porous silicone hydrogel interpenetrating polymer networks prepared using a template method for biomedical use

AbstractPorous interpenetrating polymer networks (IPNs) of polydimethylsiloxane with hydrophilic components synthesized by radical homopolymerization and copolymerization of 2‐hydroxyethyl methacrylate (HEMA) and N,N‐dimethylacrylamide (DMAA) were obtained using a template method. Surface modification of CaCO3 microsphere templates improved their dispersibility, leading to the realization of IPN films with an interconnected porous structure. Results showed that these porous IPN films exhibited higher swelling abilities, and thus better drug loading capabilities than the corresponding non‐porous films. In addition, IPNs comprised of DMAA exhibited higher swelling abilities and faster drug release rates than those of only HEMA. These silicone hydrogels were also tested for their cytotoxicity against L929 cells, confirming their non‐toxicity to cells and their potential use as materials for biomedical applications. Copyright © 2011 Society of Chemical Industry