Elaboration of a new anion-exchange membrane with semi-interpenetrating polymer networks and characterisation

A new anion-exchange membrane was prepared using the semi-interpenetrating networks (SIPN) technique. Poly(vinyl alcohol) (PVA) was chosen as the polymer matrix. Poly(1,3-diethyl-1-vinylimidazolium bromide) (PDVIBr) was first synthesised and characterised in order to use it as the cationic polyelectrolyte (Pe). The membrane was obtained by mixing aqueous PVA and Pe solutions (ratio 60/40), followed by evaporation and crosslinking with gaseous 1,2-dibromoethane. The influence of the crosslinking conditions on the sample properties was studied by infrared spectroscopy. The efficiency of the entrapment was monitored by swelling ratio and ion-exchange measurements. Ion-diffusion experiments, membrane conductivity measurements and ion-transport numbers calculations were performed on the membrane to highlight its ion-exchange properties.     

Morphology and mechanical properties of semi-interpenetrating polymer networks from polyurethane and benzyl konjac glucomannan

A series of semi-interpenetrating polymer network (semi-IPN) films coded as UB from castor oil-based polyurethane (PU) and benzyl konjac glucomannan (B-KGM) were prepared, and they have good or certain miscibility over entire composition range. Morphology, miscibility and properties of the UB films were investigated by using scanning electron microscopy (SEM), differential scanning calorimetry, dynamic mechanical analysis, ultraviolet spectrometer, wide-angle X-ray diffraction and tensile test. The results indicated that the UB films exhibited good miscibility when B-KGM content was lower than 15 wt%, resulting in relatively high light transmittance, breaking elongation and density. With an increase of the B-KGM content from 20 to 80 wt%, a certain degree of phase separation between PU and B-KGM occurred in the UB films. The tensile strength of the films UB increased from 7 to 45 MPa with an increase of B-KGM content from 0 to 80 wt%. By extracting the B-KGM with N, N-dimethylformamide from the semi-IPN, the morphology and phase domain size of the UB films were clearly observed by SEM. A continuous phase and dual-continuous phase model describing the semi-IPN were proposed to illustrate the morphology and its transition.     

Immobilization of polyisobutene in semi-interpenetrating polymer network architecture

The entrapment of linear polyisobutene (PIB) in semi-IPN architecture is shown to be as efficient as it is in cross-linkable telechelic PIB based full IPN architectures as far as the suppression of cold flow is concerned. Indeed, homogeneous linear PIB/cross-linked polycyclohexylmethacrylate (PCHMA) semi-IPNs containing from 20 to 70 wt% PIB and synthesized without solvent show no cold flow and higher mechanical properties than those of linear PIB or 50 wt% PIB containing blend. In addition, the particular barrier properties toward gas and water are preserved. Those properties arise from the phase co-continuity morphology of the semi-IPN materials which moreover compares with that of corresponding IPNs. A systematic study of the synthesis conditions (nature of the initiator, temperature, cross-linking density) showed that the reacting mixture viscosity is an important parameter that controls the phase separation degree in the final material.     

Porous polystyrene-based monolithic materials templated by semi-interpenetrating polymer networks for capillary electrochromatography

Porous polystyrene-based monolithic columns were engineered through the in-situ generation of poly(?-caprolactone) (PCL)/polystyrene (PS) semi-interpenetrating polymer networks (semi-IPNs), followed by the extraction of the uncrosslinked partner acting as a polymeric porogen. In a first stage, the semi-IPNs were prepared within the confines of fused silica capillaries by UV-initiated free-radical copolymerization of styrene and divinylbenzene, in the presence of PCL oligomers. In a second stage, the quantitative extraction of uncrosslinked oligoesters led to the formation of porous frameworks with a hierarchical porosity, as evidenced by SEM and DSC-based thermoporometry. Such as-obtained porous monoliths could be efficiently used as reversed-phase stationary phases for the separation of alkyl benzene derivatives by capillary electrochromatography (CEC).     

Shape memory polymer system of semi-interpenetrating network structure composed of crosslinked poly (methyl methacrylate) and poly (ethylene oxide)

Shape memory semi-interpenetrating polymer networks (semi-IPNs) composed of crystalline poly (ethylene oxide) (PEO) and crosslinked poly (methyl methacrylate) (x-PMMA) have been investigated. The selected compositions show shape memory property with a reasonable fast recovery (recovery time ∼1 min) and shape recovery ratio of 99%. Effects of composition (x-PMMA/PEO = 80/20…60/40) and crosslinker (triethyleneglycol dimethacrylate) concentration (up to 6 wt.%) on the creep property were also studied. The recovery time of the semi-IPNs increased and the creep compliance decreased with increasing crosslinker concentration. The network structure containing PEO crystal was characterized by scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) indicated that the PEO, present confined in the semi-IPN, melts at a lower temperature compared to the pure PEO. Dynamic mechanical analysis (DMA) showed a decrease in the glass transition (T_g) of the semi-IPN due to the phase mixing of amorphous PEO and PMMA. Both the glassy and rubbery moduli (E_g and E_r, respectively) were lower for the semi-IPNs than for the x-PMMA network. On the other hand, the E_g/E_r ratio was markedly increased for the semi-IPNs supporting an easy shaping along with a good shape fixing.     

Proton conducting membranes based on semi-interpenetrating polymer network of Nafion and polybenzimidazole

A new strategy to prepare the reinforced composite membranes for polymer electrolyte membrane fuel cells (PEMFCs), which can work both in humidified and anhydrous state, was proposed via constructing semi-interpenetrating polymer network (semi-IPN) structure from polybenzimidazole (PBI) and Nafion^®212, with N-vinylimidazole as the crosslinker. The crosslinkable PBI was synthesized from poly(2,2′-(m-phenylene)-5,5′-bibenzimidazole) and p-vinylbenzyl chloride. The semi-IPN structure was formed during the membrane preparation. The composite membranes exhibit excellent thermal stability, high-dimensional stability, and significantly improved mechanical properties compared with Nafion^®212. The proton transport in the hydrated composite membranes is mainly contributed by the vehicle mechanism, with proton conductivity from ∼10⁻² S/cm to ∼10⁻¹ S/cm. When the temperature exceeds 100 °C, the proton conductivity of the semi-IPN membranes decreases quickly due to the dehydration of the membranes. Under anhydrous condition, the proton conductivity of the membranes will drop to ∼10⁻⁴ S/cm, which is also useful for intermediate temperature (100-200 °C) PEMFCs. The benzimidazole structure of PBI and the acidic component of Nafion^® provide the possibility for the proton mobility via structure diffusion involving proton transfer between the heterocycles with a corresponding reorganization of the hydrogen bonded network.     

Investigation of the preparation and physical properties of a novel semi-interpenetrating polymer network based on epoxised NR and PVA using maleic acid as the crosslinking agent

Natural rubber (NR) and its derivatives as renewable and biodegradable materials have attracted considerable attention because of the serious pollution problems caused by synthetic materials and a shortage of resources. A new semi-interpenetrating polymer network (semi-IPN) based on epoxidised natural rubber and polyvinyl alcohol containing maleic acid as a crosslinking reagent was synthesized and characterized by FTIR, XRD, SEM, swelling ratio in both distilled water and toluene, and mechanical properties. The curing time and dose of maleic acid were varied from 10 to 60 min, and from 10 to 60% (w/w), respectively. An IR spectroscopic study indicated the presence of an ester linkage at 1730 cm⁻¹ in maleic acid crosslinked with PVA in semi-IPN films. In addition, the crystalline content of PVA dramatically decreased after adding maleic acid in the semi-IPN, as observed from its XRD. The semi-IPNs exhibit good mechanical properties, thermal stability, characteristics of a polyvinyl alcohol–maleic acid polymer network. An SEM of the semi-IPNs containing maleic acid showed no phase separation, when compared with the sample prepared in the absence of maleic acid.     

Preparation of organic/inorganic hybrid semi-interpenetrating network polymer electrolytes based on poly(ethylene oxide-co-ethylene carbonate) for all-solid-state lithium batteries at elevated temperatures

Organic/inorganic hybrid semi-interpenetrating network (semi-IPN) polymer electrolytes (HIPEs) based on poly(ethylene oxide-co-ethylene carbonate) (PEOEC) have been developed for all-solid-state lithium battery applications. In comparison to those of poly(ethylene oxide) (PEO), salient features of the PEOEC are the amorphous nature and high dielectric constant, which provide enhanced ionic conductivity. The organic/inorganic hybrid network matrix in the HIPEs is composed of different contents of photo-cross-linked octa-functional POSS acrylate (OA-POSS) and ethoxylated trimethylolpropane triacrylate (ETPTA). The effect of OA-POSS on solid-state electrolyte properties of the HIPEs is investigated in terms of the dimensional stability, thermal behavior, and ionic conductivity. Due to the presence of the rigid and bulky POSS moiety, the HIPEs exhibit improvement in ionic conductivity along with enhanced dimensional stability. The high capacity and good cycle performance of lithium batteries with the HIPEs demonstrate feasibility of applying the HIPEs to solid-state electrolytes for all-solid-state lithium batteries that can operate at elevated temperatures.     

Self-supported semi-interpenetrating polymer networks for new design of electrochromic devices

This paper reports the preparation of conducting films combining linear poly(3,4-ethylenedioxythiophene) (PEDOT) and cross-linked polyethylene oxide (PEO) into semi-interpenetrating networks. Due to the synthetic pathway, PEDOT is distributed within the PEO matrix and specifically along the two outer faces of the film. Such a distribution of the conducting polymer inside the matrix leads to the design of a self-supported and symmetrical PEDOT-Polymer electrolyte-PEDOT electrochromic device which can substitute the usual multilayer configuration. Optical contrast ΔT_630 nm (%) up to 33% is reached without contrast loss after 1500 switches. The switching time is 30 s for bleaching with a good memory effect (less than 1% decrease of transmittance after 1 h) of the device.     

具有IPN结构的复合超滤膜在华北油田的应用研究

在复合膜的制备过程中,膜材料中高分子聚合物很难混合。作者在聚合物－溶剂－聚合物体系中加入一种增溶剂,改变了聚合物在溶液中的聚积状态,由于是部分混溶,在膜的形态过程中各部分聚合物凝胶机理不一样,在表面功能层与下部支撑层这宰一层由两聚合物交互互相贯穿的网络结构,作者研究了形成此膜的各种影响因素。     

Lithium polymer batteries using the highly porous membrane filled with solvent-free polymer electrolyte

Solid polymer electrolyte supported by a microporous membrane was prepared and characterized. The polymer electrolyte was prepared by penetrating the highly conductive solvent-free polymer electrolyte based on poly(oligo [oxyethylene] oxyterephthaloyl) into the pores of the highly porous membrane. The electrochemical characteristics of the solid polymer electrolytes are presented, and we discuss the possibility of them as an electrolyte material for lithium polymer batteries.     

A study of diffusion in poly(ethyleneglycol)-gelatin based semi-interpenetrating networks for use in wound healing

Semi-interpenetrating networks (sIPNs) designed to mimic extracellular matrix via covalent crosslinking of poly(ethylene glycol) diacrylate in the presence of gelatin have been shown to aid in wound healing, particularly when loaded with soluble factors. Ideal systems for tissue repair permit an effective release of therapeutic agents and flow of nutrients to proliferating cells. Appropriate network characterization can, consequently, be used to convey an understanding of the mass transfer kinetics necessary for materials to aid in the wound healing process. Solute transport from and through sIPNs has not yet been thoroughly evaluated. In the current study, the diffusivity of growth factors and nutrients through the polymeric system was determined. Transport of keratinocyte growth factor was modeled by treating the sIPN as a plane sheet into which the protein was loaded. The diffusion coefficient was determined to be 4.86 × 10⁻⁹ ± 1.86 × 10⁻¹² cm²/s. Glucose transport was modeled as flow through a semi-permeable membrane. Using lag-time analysis, the diffusion coefficient was calculated to be 2.25 × 10⁻⁶ ± 1.98 × 10⁻⁷ cm²/s. The results were evaluated in conjunction with previous studies on controlled drug release from sIPNs. As expected from Einstein-Stokes equation, diffusivity decreased as molecular size increased. The results offer insight into the structure-function design paradigm and show that release from the polymeric system is diffusion controlled, rather than dissolution controlled.     

Electro-generation of 3-methyl-2-formylaminopyridine using a bipolar membrane as separator

A mSA–mCS bipolar membrane was prepared by sodium alginate/polyvinyl alcohol (SA/PVA) and chitosan/polyvinyl alcohol (CS/PVA) modified by Fe³⁺ and glutaraldehyde as linking reagents, respectively. The mSA–mCS bipolar membrane was investigated by FT-IR, SEM, I–V curves, ion exchange capacity and changes of pH in the anode and cathode chambers. The SA–CS/PVA bipolar membrane was used as a separator in the electrolysis cell to electrogenerate 3-methyl-2-formylaminopyridine. The product yield was 49.8% and higher than that produced in a Nafion mono-membrane-equipped cell. Compared with the traditional chemistry method, the electro-generating process is moderate and eliminates pollution to the environment.     

PDMS/PVDF microporous membrane with semi‐interpenetrating polymer networks for vacuum membrane distillation

In this article, using the non‐solvent induced phase separation process, a new microporous membrane with the semi‐interpenetrating polymer network (semi‐IPN) structure was produced. For this membrane, polydimethylsiloxane (PDMS) polymer is crosslinking and poly(vinylidene fluoride) (PVDF) polymer is linear, by changing the mass ratio of PDMS/PVDF, the structure and the performance of the prepared membranes were studied. The membranes were also investigated by attenuated total reflection‐Fourier transform infrared (ATR‐FTIR), scanning electron microscopy–energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, thermogravimetric analysis, and water contact angle, etc. ATR‐FTIR spectroscopy confirmed the formation of semi‐IPN; compared with the PDMS/PVDF polymer without semi‐IPNs structure, the viscosity of the semi‐IPNs structured casting solution increased, membrane mechanical property increased but its hydrophobicity decreased. Using the resulting membranes for the vacuum membrane distillation desalt of the NaCl solution (30 g/L), 99.9% salt rejection and reasonable flux were obtained. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45792.     

A study of epoxy resin–acrylated polyurethane semi-interpenetrating polymer networks

Epoxy resin–acrylated polyurethane semi-interpenetrating polymer networks (semi-IPNs) were synthesized containing various ratios of the diglycidyl ether of bisphenol-A (DGEBA)-based epoxy resin and an acrylated aliphatic urethane oligomer. The synthesis was carried out in the presence of a mixture of triarylsulfonium hexafluoroantimonate salts as a dual photoinitiator that initiates both the cationic polymerization of the epoxy resin and the free-radical polymerization of the acrylated urethane oligomer simultaneously, upon irradiation with ultraviolet light. The simultaneous photopolymerization, followed by isothermal differential scanning calorimetry measurements, gave rise to simultaneous semi-interpenetrating polymer networks (semi-SINs). During polymerization, partial inhibition of the cationic polymerization was noticed. This was investigated by determination of the gel content and the infrared spectroscopy of the soluble fraction, after extraction of the synthesized polymer films in a Soxhlet apparatus, and by determination of the network density of investigated systems with thermal mechanical analysis. The compatibility of the components in the semi-IPNs was investigated by dynamic mechanical thermal analysis. It was found that glass transition temperatures are shifted inwardly, which indicated that the epoxy resin–acrylated polyurethane semi-IPNs were compatible. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:111–119, 1998     

New polymer bipolar plates for polymer electrolyte membrane fuel cells: Synthesis and characterization

Carbon black (CB) and polyvinylidene fluoride (PVDF) composites were obtained and subsequently characterized, both microstructurally (DSC and DMA) and electrically. In addition, the electrochemical performance of these materials was tested in the form of bipolar plates, expressly manufactured for this purpose and incorporated in a conventional fuel cell. The results obtained allow for the conclusion that CB incorporation into PVDF yields polymer composite materials with electrical conductivity of about 2.4 S/cm, which may be thermically processed and given any convenient shape with the means conventionally applied in the field of polymer technologies. It was found that CB concentration slightly affects the microstructural parameters of the composites (melting temperature, glass‐transition temperature, Avrami kinetic parameters, etc.). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2817–2822, 2002; DOI 10.1002/app.10257     

A non-compensatory compromised solution for material selection of bipolar plates for polymer electrolyte membrane fuel cell (PEMFC) using ELECTRE IV

A non-compensatory compromised approach in decision analysis is described within the context of the material selection of the bipolar plate of a polymer electrolyte fuel cell. ELECTRE IV, using embedded outranking relations, has been applied to determine the best compromised possible candidate material, considering all the performance indices including the cost criterion. This study also investigates the effect of replacing components of the selection parameters (i.e. design parameters) with performance indices to solve the same problem. The individual effect of the components of the performance indices on the ranking change in each possible candidate material is studied. It was shown that the ELECTRE IV lists candidate materials from best to worst, taking into account all the material selection criteria. The obtained results show good agreement with available reported results.     

Damping,thermal, and mechanical performances of a novel semi-interpenetrating polymer networks based on polyimide/epoxy

In this article, a series of novel semi-interpenetrating polymer networks (s-IPNs) based on linear polyimide (PI) and crosslinked epoxy (EP) were firstly prepared aiming at controlling violent vibration and noise originating from operation of the machine. The damping, thermal, and mechanical performances of s-IPNs films were systematically investigated in terms of the structure of polyimide (the molar ratios of diamines) and the component ratios of PI/EP. The results indicate that PI/EP s-IPNs films exhibit prominent damping properties, and the effective damping temperature range can reach up to 58.8 °C when molar ratio of diamines is 1:3 within PI and component ratio of PI/EP is 70:30. Meanwhile, all the PI/EP s-IPNs films show good thermal stability compared to cured EP and certain mechanical behaviors due to the formation of semi-interpenetrated structure. Meaningfully, the prepared novel PI/EP s-IPNs will be used as effective damping materials and have a potential application in damping fields. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48032.     

Elaboration of ion‐exchange membranes with semi‐interpenetrating polymer networks containing poly(vinyl alcohol) as polymer matrix

Ion‐exchange membranes were prepared with semi‐interpenetrating networks (s‐IPNs) by mixing a film‐forming polymer, poly(vinyl alcohol) (PVA), for the crosslinked matrix and a polyelectrolyte for the specific ion‐exchange property. Poly(sodium styrenesulfonate) (PSSNa), poly(styrenesulfonic acid) (PSSH), and poly(acrylic acid) (PAA) were used as anionic polyelectrolytes. Polyethyleneimine (PEI), poly(1,1‐dimethyl‐3,5‐dimethylenepiperidinium chloride) (PDDPCl), and poly(diallyldimethylammonium chloride) (PDDMACl) were used as cationic polyelectrolytes. Membranes with PVA 60% and polyelectrolyte 40% showed the best compromise among mechanical, homogeneous, and ion‐exchange properties. Gaseous dibromoethane was used as a crosslinking agent to form the PVA network and for efficient entrapment of the polyelectrolyte in the membrane. The crosslinking time (tc) was optimized for each type of membrane and its influence was studied by thermogravimetric analysis of the sample and scanning electron microscopy observations. The best results (large ion‐exchange capacity and small swelling ratio) were obtained for PVA/PAA and PVA/PSSNa/PSSH membranes. Among anion‐exchange membranes, PVA/PEI gave the best permselectivity (low co‐ion leakage) and the highest ion‐exchange capacity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1572–1580, 2002; DOI 10.1002/app.10420