Preparation and characterization of semi‐interpenetrating network polystyrene/PVDF cation exchange alloy membranes

The polystyrene‐DVB/PVDF alloy particles were prepared by pulverizing the polymerization product of styrene/DVB/PVDF in DMF, and then sulfonated with concentrated sulfuric acid to gain the cation exchange alloy powder, which was directly thermoformed by a hot‐press machine to form the titled cation exchange alloy membranes with the structure of semi‐interpenetrating polymer network. The effects of the polystyrene‐DVB to PVDF mass ratio and the DVB content in the monomers on the physical and electrochemical properties of the prepared alloy membranes were investigated. While the Fourier transform infrared spectroscopy (FTIR) confirms the components of membranes, the scanning electron microscopy (SEM) reveals that the alloy membranes possess a uniform distribution of functional groups, and a more dense structure with the increases of DVB content and PVDF content. The optimal prepared membranes have the area electrical resistance values within 3.0–6.6 Ω·cm², obviously superior to the commercial heterogeneous cation exchange membrane, as well as the moderate water contents of 35–40% and the desirable permselectivity with a transport number more than 0.95. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1220‐1227, 2013     

Novel polymer electrolyte membranes based on semi‐interpenetrating blends of poly(vinyl alcohol) and sulfonated poly(ether ether ketone)

In this work, the properties of novel ionic polymer blends of crosslinked and sulfonated poly(vinyl alcohol) (PVA) and sulfonated poly(ether ether ketone) (SPEEK) are investigated. Crosslinking and sulfonation of PVA were carried out using sulfosuccinic acid (SSA) in the presence of dispersed SPEEK to obtain semi‐interpenetrating network blends. PVA–SSA/SPEEK blend membranes of different compositions were studied for their ion‐exchange capacity, proton conductivity, water uptake, and thermal and mechanical properties. The hydrated blend membranes show good proton conductivities in the range of 10^?3 to 10^?2 S/cm. When compared with pure component membranes, the PVA–SSA/SPEEK blend membranes also exhibit improvement in tensile strength, tensile modulus, and delay in the onset of thermal and chemical degradation. Semi‐interpenetrating nature of the blends is established from morphology and dynamic mechanical analysis. Morphology of the membranes was studied using scanning electron microscopy after selective chemical treatment. The dynamic mechanical properties of the membranes are examined to understand the miscibility characteristics of the blends. The relative proportions of PVA and SPEEK and the degree of crosslinking of PVA–SSA are important factors in determining the optimum properties for the blend. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

A novel pH‐sensitive gelatin–DNA semi‐interpenetrating polymer network hydrogel

Gelatin and DNA were mixed together in various ratios followed by the addition of glutaraldehyde as a cross‐linker. FT‐IR spectroscopy confirmed the formation of a semi‐interpenetrating polymer network (semi‐IPN) between the gelatin and DNA. The gelatin–DNA semi‐IPN hydrogel underwent, reversibly, remarkable changes in swelling degree in response to the variation of pH. In the low‐pH range, the hydrogel showed a lower swelling degree; with an increment in pH, the hydrogel was highly swollen, which is considered to originate from the complexation and de‐complexation between gelatin and DNA, as was verified by turbidity measurements. Higher contents of DNA result in an increase in the swelling degree, which is presumably due to the easy outward expansion of free DNA moieties. The permeability coefficient, P, for a model molecule, cimetidine, through the semi‐IPN hydrogel membranes was determined in pH 1.0 and pH 12.0 buffer solutions. The results show that the permeation of cimetidine is responsive to pH change, and an evident variation in the P values occurs in response to the pH of the media. Copyright © 2004 Society of Chemical Industry     

Fluid flow modeling in a sulfonated cation‐exchange membrane

Liquid permeation measurements of water, methanol, and 2‐propanol were carried out using a commercial cation‐exchange membrane Nafion‐117 (perfluorinated polyethylene with pendant ether‐linked side chains terminated with sulfonated groups). The experimental permeation data are treated and analyzed using the capillary model, leading to the determination of equivalent pore radius of the membrane structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Morphology,mechanical properties,and failure topography of semi‐interpenetrating polymer networks based on natural rubber and polystyrene

Semi‐interpenetrating networks (semi‐IPNs) were prepared from natural rubber (NR) and polystyrene (PS) by the sequential method. In these semi‐IPNs the NR phase was crosslinked while the PS phase was uncrosslinked. Different initiating systems such as dicumyl peroxide (DCP), benzoyl peroxide (BPO), and the azobisisobutyronitrile (AIBN) system were used for polymerizing the PS phase. The blend ratio was varied by controlling the swelling of NR in the styrene monomer. The mechanical properties of the semi‐IPNs, namely, density, tensile strength, tear strength, elongation at break, tension set, tensile set, impact strength, and hardness, were determined. The morphology of different IPNs was studied using scanning electron microscopy. A compact morphology with a homogeneous phase distribution was observed in the semi‐IPNs. The properties of the semi‐IPN do not change much with the initiating system. However, in most cases, the DCP initiating system showed slightly superior performance. The tensile and tear‐strength values of the IPNs were found to increase with increasing plastomer content. The crosslink density of the semi‐IPNs also increased with increase in the polystyrene content. The experimental values were compared with theoretical models such as series, parallel, Halpin Tsai, Coran, Takayanaki, Kerner, and Kunori. The tensile and tear‐fracture surfaces were examined using a scanning electron microscope. The fracture patterns were correlated with the strength and nature of the failure. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2327–2344, 2000     

Studies on engineering properties of PVC–PMMA semi‐interpenetrating polymer networks

Semi1 and semi2 interpenetrating polymer networks (IPNs) of PVC and in situ formed PMMA have been synthesized using diallyl phthalate and ethylene glycol dimethacrylate as the crosslinkers of PVC and PMMA, respectively. These two types of IPNs have been compared w.r.t their physical, mechanical, and thermal properties and an endeavor has been made to find a correlation of these properties with the morphology generated in these systems. The semi1 IPNs displayed a decrease in their mechanical parameters and the physical properties as well, while in contrast, the semi2 IPNs exhibited a marginal increase in the corresponding values after an initial drop upto about 15% of crosslinked PMMA incorporation when compared to the crosslinked PVC in the case of semi1 IPN and linear PVC in the case of semi2 IPN. The various samples of semi1 and semi2 IPNs showed a two‐stage degradation typical of PVC, while confirming the increased stability with the samples having higher percentages of PMMA. The influence of crosslinking of the major matrix in semi1 IPN was almost counterbalanced by the influence of crosslinking in the dispersed PMMA phase in the case of semi2 IPN. The softening characteristics as detected by the extent of penetration of the probe, as has been detected by thermomechanical analysis, are in conformity with their mechanicals. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1725–1735, 2005     

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.     

Sulfonated polyimide and poly (ethylene glycol) diacrylate based semi‐interpenetrating polymer network membranes for fuel cells

Semi‐interpenetrating polymer network (semi‐IPN) membranes based on novel sulfonated polyimide (SPI) and poly (ethylene glycol) diacrylate (PEGDA) have been prepared for the fuel cell applications. SPI was synthesized from 1,4,5,8‐naphthalenetetracarboxylic dianhydride, 4,4′‐diaminobiphenyl 2,2′‐disulfonic acid, and 2‐bis [4‐(4‐aminophenoxy) phenyl] hexafluoropropane. PEGDA was polymerized in the presence of SPI to synthesize semi‐IPN membranes of different ionic contents. These membranes were characterized by determining, ion exchange capacity, water uptake, water stability, proton conductivity, and thermal stability. The proton conductivity of the membranes increased with increasing PEGDA content in the order of 10^?1 S cm^?1 at 90°C. These interpenetrating network membranes showed higher water stability than the pure acid polyimide membrane. This study shows that semi‐IPN SPI membranes based on PEGDA which gives hydrophilic group and structural stability can be available candidates comparable to Nafion® 117 over 70°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Characterization of cation‐exchange membrane fouling during bipolar membrane electrodialysis of monosodium glutamate isoelectric supernatant

BACKGROUND: A novel procedure that involved regeneration and recycling of ammonia and sulfuric acid from monosodium glutamate isoelectric supernatant with bipolar membrane electrodialysis (BMED) was proposed. As the performance of the membranes deteriorated during the batch runs, fouling of the cation‐exchange membrane (CEM) in contact with the base cell was studied. RESULTS: During ten consecutive batches of BMED, some operating parameters deteriorated gradually. Using scanning electron microscopy observations, fouling deposits were found on the CEM surface on the base cell side. Using Fourier transform infrared spectroscopy and reversed‐phase high‐performance liquid chromatography (RP‐HPLC), the organic fouling fraction of the CEM foulants was found to contain eight amino acids. Using X‐ray energy‐dispersive analysis, the mineral fouling fraction was shown to be mainly O and Ca elements, and a little Mg. Using X‐ray diffraction, the inorganic foulant was identified as CaCO₃, mainly in the form of calcite and a little aragonite. CONCLUSION: The CEM was subject to membrane fouling consisting of an organic fouling fraction and a mineral fraction. The organic fraction occurred as ions with some positive charges from the isoelectric supernatant and probably existed in the form of amino acids or their peptides. The mineral fraction was mainly CaCO₃ calcite and aragonite, and probably a little amorphous Ca and Mg hydroxides. Copyright © 2011 Society of Chemical Industry     

Preparation and characterization of acrylic acid‐treated bacterial cellulose cation‐exchange membrane

The feasibility of using bacterial cellulose as a source for environmentally compatible ion‐exchange membranes (IEM) was studied. Bacterial cellulose was modified with cation‐exchangeable acrylic acid (AAc) by UV‐graft polymerization to prepare membranes having ion‐exchange capacity (IEC) and greater structural density. Fourier transform infrared (FTIR) spectra showed that acrylic acids were successfully bound to bacterial cellulose. Morphological changes of acrylic acid‐treated bacterial cellulose were examined through scanning electron microscopy. A dense structure of the membrane increased with increasing UV‐irradiation time. Acrylic‐modified bacterial cellulose membrane showed reasonable mechanical properties, such as tensile strength of 12 MPa and elongation of 6.0%. Also the prepared membranes were comparable to the commercial membrane CMX in terms of the electrochemical properties, ie IEC of 2.5 meq g^?1‐dry mem, membrane electric resistance of 3 ohm cm², and transport number of 0.89. Copyright © 2003 Society of Chemical Industry     

Synthesis and characterization of cation‐exchange membrane based on sulfonated sty/HEA/LMA terpolymer

A cation‐exchange membrane based on a styrene/hydroxyethyl acrylate/lauryl methacrylate (Sty/HEA/LMA) terpolymer was prepared via a postsulfonation reaction for various sulfonation times. Sulfonic groups were introduced into the membrane structure with sulfuric acid as the sulfonating agent and silver sulfate as an initiator in a nitrogen atmosphere. Sulfonated Sty/HEA/LMA terpolymer membranes were characterized by Fourier transform infrared (FTIR) spectrometry and nuclear magnetic resonance as well as by determining the degree of sulfonation (DS), ion‐exchange capacity (IEC), water uptake (WU), and electrical property of the membranes. The presence of sulfonic groups in the sulfonated Sty/HEA/LMA terpolymer was confirmed by FTIR, and the resulting membrane showed an IEC of 1.29 meq/g and an electrical resistance of 0.1 Ω cm². The WU of the prepared membranes increased with the DS at the reaction time. The surface morphology obtained by atomic force microscopy clearly showed an increase of roughness with reaction time. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Novel semi‐interpenetrating network structural phase change composites with high phase change enthalpy

High phase change enthalpy, controllable temperature, and stable shape can expand the application of phase change materials (PCMs) in energy storage. In this study, a series of novel form‐stable PCMs with high phase change enthalpy (169–195 J/g) and controllable temperature (45.3–61.4°C) were prepared. The PCMs exhibited a semi‐interpenetrating polymer network (semi‐IPN) structure resulting from the combination of polyethylene glycol (PEG) and a three‐dimensional (3‐D) network gel. The gel itself featured an inherent phase change characteristic and a 3‐D network structure. Thus, it improved the phase transition enthalpy of the materials and facilitated the formation of a semi‐IPN that endowed the materials with excellent form‐stable properties. In addition, the latent heat of the composites (169–195 J/g) is much higher than most of the previously reported composites using PEG as phase change component (68–132 J/g). © 2017 American Institute of Chemical Engineers AIChE J, 64: 688–696, 2018     

Comparison of the pervaporation separation of a water–acetonitrile mixture with zeolite‐filled sodium alginate and poly(vinyl alcohol)–polyaniline semi‐interpenetrating polymer network membranes

The pervaporation (PV) separation performance of ZSM‐5‐ and Na‐Y‐type zeolite‐filled sodium alginate (NaAlg) membranes were compared with those of pure NaAlg and semi‐interpenetrating polymer network (semi‐IPN) membranes of poly(vinyl alcohol) (PVA) with polyaniline (PANI) for the dehydration of acetonitrile. The PV separation characteristics of the zeolite‐filled membranes showed a dependence on the nature of the zeolites. The variation of the acidity function of the ZSM‐5 zeolite had an influence on the flux and selectivity of the membranes when compared to unfilled membranes. The crosslinked membranes were characterized by differential scanning calorimetry, X‐ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. Increasing the PANI content of the semi‐IPN network increased the separation selectivity. Among the NaAlg membranes, the plain NaAlg membrane showed the highest selectivity of 414 at 30 mass % water in the feed mixture, whereas the Na‐Y‐ and ZSM‐5 (40)‐filled NaAlg membranes exhibited much lower values of selectivity, that is, 7.3 and 4.3, respectively for 30 mass % water in the feed. When the flux and selectivity data of ZSM‐5 (250)‐filled NaAlg membranes were compared with that of Na‐Y‐ or ZSM‐5 (40)‐filled NaAlg membranes, a noticeable increase in the selectivity for the ZSM‐5 (250)‐filled NaAlg membrane was observed, but a somewhat comparable flux was observed compared to the plain NaAlg membrane. For the first time, PANI was polymerized with PVA to yield a semi‐IPN. The total flux and water flux increased systematically, whereas the selectivity decreased greatly from 251.87 to 5.95 with increasing amounts of water in the feed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1968–1978, 2005     

Synthesis and swelling properties of pH‐sensitive hydrogels based on chitosan and poly(methacrylic acid) semi‐interpenetrating polymer network

A novel semi‐interpenetrating polymer network (semi‐IPN) hydrogel composed of chitosan and poly(methacrylic acid) was synthesized using formaldehyde as a crosslinker. The amount of crosslinker was searched and optimized. The structure of the hydogel was investigated by Fourier transform infrared (FTIR) spectroscopy. The spectrum shows that a structure of polyelectrolyte complex exists in the hydrogel. The effects of pH, ionic strength, and inorganic salt on the swelling behaviors of the hydrogel were studied. The results indicate the hydrogel has excellent pH sensitivity in the range of pH 1.40 to 4.50, pH reversible response between pH 1.80 and 6.80, and ionic strength reversible response between ionic strength 0.2 and 2.0M. The results also show that the hydrogel has a bit higher swelling capacity in a mix solution of calcium chloride (CaCl₂) and hydrochloric acid (HCl) solution than in a mix solution of sodium chloride (NaCl) and HCl. These results were further confirmed through morphological change measured by scanning electron microscope (SEM). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1720–1726, 2005     

Lead removal from aqueous solutions by 732 cation‐exchange resin

Kinetics and thermodynamics of the removal of Pb²⁺ from an aqueous solution by 732 cation‐exchange resin in hydrogen type (732‐CR) were studied in the temperature range of 298–328 K and Pb²⁺ concentration range of 5–50 mol/m³. The effects of ion exchange temperature and initial lead ion concentration on the time evolution of the experimental concentration for the metal ion were investigated. Ion exchange kinetics of Pb²⁺ onto 732‐CR follow the Nernst‐Planck equation and unreacted‐core model (UCM). The diffusion coefficients of counter ions and the efficient diffusion coefficient of lead ions within the resin were calculated. The results show that the ion exchange process is favoured under the particle diffusion control mechanism. The ion exchange isotherm data agreed closely with the Langmuir isotherm. The maximum monolayer exchange capacity for Pb²⁺ was found to be 484.0 mg/g at 308 K. Thermodynamic studies show that Pb²⁺ onto 732‐CR is spontaneous and exothermic in nature. The ion exchange processes were verified by Energy Disperse Spectroscopy (EDS).     

Morphology development in polychloroprene–polystyrene latex interpenetrating polymer networks

Latex interpenetrating polymer networks (LIPNs) have been prepared using a crosslinked polychloroprene latex as the seed emulsion, followed by the in situ polymerization of styrene, typically with a 10% divinyl benzene crosslinker. Polychloroprene–crosslinked polystyrene (XPS) ratios ranging from 70/30 to 40/60 were used, with the second monomer being added as a single aliquot rather than by “starvation” routes. The majority of the work has been conducted using the water‐soluble persulfate initiator method, which entails lengthy (∼ 6 h) polymerizations. To follow the development of microstructure, polymerizations were also stopped at 0.5, 1, and thence hourly intervals up to 6 h, so that any effect of time on shell and domains could be seen by transmission electron microscopy (TEM). Parallel studies using azo‐bis(isobutyronitrile) (AIBN) as initiator at the same temperature were conducted. Products were also studied, after staining, by TEM. For the persulfate initiator, domain structures predominated for the 70/30 ratio, but polystyrene‐rich shells are found in all cases, with increasing thickness as the chloroprene/styrene ratio was reduced. The styrene‐rich products (i.e., 40/60 Neoprene/XPS ratio) appear to have larger unstained domains suggesting phase separation. For the AIBN‐initiated styrene polymerization, shells are less evident, and where they exist, are both thinner and less continuously developed. Domain sizes are somewhat larger. This relatively hydrophobic initiator has caused polymerization predominately in the interior of each latex particle. The particle size distribution of the seed neoprene latex is broad and bimodal. As the LIPNs form, the larger diameter component increases and little evidence for fresh nucleation, in the form of small diameter particles, is seen. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 629–638, 1999     

Polyurethane–epoxy maleate of bisphenol a semi‐interpenetrating polymer networks

Semi‐interpenetrating polymer networks were synthesized starting from polyurethane (PU) and epoxy maleate of bisphenol A (EMBA). Differential scanning calorimetry and swelling measurements showed good miscibility and the presence of the strong intermolecular interactions within the synthesized networks. The physicomechanical properties increased against PU to a maximum value with the increasing of EMBA content up to 12 wt % and then decreased with further increasing EMBA content. Generally, with exception of the elongation at the limit of elasticity, the mechanical properties improved very much under action of the UV radiation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 138–144, 2002     

Cellulose–chitosan interpenetrating polymer network for electro‐active paper actuator

In this article, the cellulose‐chitosan interpenetrating polymer network (IPN) films were prepared and fabricated as the electro‐active paper actuator. The characteristics of the cellulose–chitosan IPN films were examined by SEM, FT‐IR, XRD, DSC, and tensile test. The performance of the IPNs based actuator was evaluated in terms of bending displacement with respect to the actuation frequency, voltages, humidity levels, chitosan content, and time variation. It was observed that with chitosan content increasing in the IPNs, the crystallinity decreased and the network became denser, which caused the Young's modulus to increase. Chitosan content in IPNs also significantly affected the bending performance. The optimum IPN weight ratio of cellulose and chitosan was 60 : 40. The maximum bending displacement of 7.2 mm was found at 80% relative humidity level. In terms of durability, the bending lifetime at 70% humidity level was about 10 h with 17% performance degradation. More issues on the actuator performance and durability are addressed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Insolubilization of sodium chondroitin sulfate by forming a semi‐interpenetrating polymer network with acrylic acid: A potential carrier for colon‐specific drug delivery

To reduce the highly hydrophilic property of chondroitin sulfate (ChS), a semi‐interpenetrating polymer network (semi‐IPN) of chondroitin sulfate/polyacrylic acid (PAA) was prepared as a drug carrier by crosslinking acrylic acid with diethyleneglycol diacrylate. The swelling properties of the semi‐IPNs with different concentrations of crosslinking agent were correlated. The moisture sorption profiles were evaluated using differential thermal analysis. Ketoprofen was used as a drug probe to evaluate the performance of the drug released from the semi‐IPN matrices. The prepared semi‐IPNs demonstrated significant swelling reduction properties with both gastric and intestinal fluids compared with those of both the pure ChS and the ChSAA blend without the crosslinking agent. The amount of accumulated drug released from the semi‐IPNs was less than 30 wt % at pH 1.2 and up to 80 wt % at pH 7.4. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 114–122, 2002