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     

Dynamic mechanical study of filled semi-interpenetrating polymer networks: Influence of γ-Fe2O3 on microphase structure

The preparation of filled two-component semi-interpenetrating polymer networks (semi-IPNs) is described and the results of an investigation of their morphology by means of dynamic mechanical spectroscopy are considered. The influence of an active dispersed filler (γ-Fe₂O₃) on the semi-IPNs phase structure is studied. A comparison is made between filled and unfilled semi-IPNs consisting of compatible or incompatible polymers. In the case of a semi-IPN of compatible polymers, the introduction of γ-Fe₂O₃ was observed to cause phase separation. With a two-phase semi-IPN the introduction of the filler enhanced the phase separation. The presence of two distinct peaks (the dynamic glass transition temperatures) corresponding to those of the two initial homopolymers shows the semi-IPN to have a two-phase structure.     

pH-sensitive hydrogels based on polyvinylpyrrolidone–polyacrylic acid (PVP–PAA) semi-interpenetrating networks (semi-IPN): Swelling and controlled release

Complexes of polyvinylpyrrolidone–polyacrylic acid (PVP–PAA) photopolymerized from a mixture of PVP and acrylic acid (AA) were characterized by means of differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectrometry. The swelling of PVP–PAA semi-interpenetrating network (semi-IPN) films was studied in various pH media. The results showed that swelling in 0.1N HCl solution and pH 3.0 phosphate buffer was strikingly different from that in the pH 6.0 phosphate buffer. Caffeine release rate from the semi-IPN film followed Fick's Law. The rate of release was higher in dissolution media having pH above a critical value of about 3.8. Control of caffeine release from the semi-IPN film was realized by changing cyclically the pH of dissolution medium between 0.1N HCl solution and pH 6.0 phosphate buffer. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 921–930, 1998     

Segmented polymer networks based on poly(N-isopropyl acrylamide) and poly(tetrahydrofuran) as polymer membranes with thermo-responsive permeability

Segmented polymer networks (SPNs) containing a polymer with a lower critical solution temperature were prepared by free radical copolymerization of poly(tetrahydrofuran) (PTHF) bis-macromonomers with N-isopropyl acrylamide (NIPAA). The PTHF bis-macromonomers, which were prepared by living cationic polymerization of tetrahydrofuran, were provided with acrylate or acrylamide end-groups by end-capping the living polymer chains with acrylic acid and 3-acrylaminopropanoic acid, respectively. Differential Scanning Calorimetry (DSC) experiments showed clearly that, for the same fractions of both network components, the phase morphology of the SPNs was highly influenced and adjustable by the nature of the end-groups of the bis-macromonomer as a result of their copolymerization behavior with NIPAA. For the same type of multi-component networks, the morphology changed from a heterogeneous up to a rather homogeneous nature by application of bis-macromonomers with, respectively, acrylate or acrylamide end-groups during their preparation. Swelling and DSC experiments on the swollen SPNs revealed, respectively, that the swelling properties and the cloud point temperature (T_cp) could be controlled by the network composition. The thermo-responsive water permeability and the possible application of the SPNs as pervaporation membranes for the separation of a water/isopropanol mixture were investigated as a function of temperature and network composition. The permeability and selectivity of the membranes decrease when the T_cp is reached. The permeability increases while the selectivity decreases with decreasing crosslink density or higher overall hydrophilicity of the SPNs.     

Adsorption of cationic dyes on poly(acrylic acid‐co‐sodium acrylate‐co‐acrylamide) superabsorbents

Inverse suspension polymerization was carried out to synthesize poly(acrylic acid‐co‐sodium acrylate‐co‐acrylamide) superabsorbent polymers (SAPs) crosslinked with ethylene glycol dimethacrylate (EGDMA). The equilibrium swelling capacities of the SAPs, determined by swelling them in DI water, were found to vary with the acrylamide (AM) content. The SAPs were used to adsorb four cationic dyes (Acriflavine, Auramine‐O, Azure‐I and Pyronin‐Y). The effect of AM content in the SAPs on the adsorption of the cationic dyes was investigated. Different initial concentrations of Azure‐I were used with the same amount of the SAP to explore the effect of initial dye concentration on the adsorption. The effect of the adsorbent amount was investigated by taking different amounts of SAP with a fixed initial concentration of Acriflavine. The kinetics of the dye adsorption was modeled by a first order model and the equilibrium amount of the dye adsorbed, adsorption rate coefficients, removal efficiency and partition coefficients were determined. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Self‐assembly of alginate/polyethyleneimine multilayer onto magnetic microspheres as an effective adsorbent for removal of anionic dyes

A novel magnetic adsorbent alginate/polyethyleneimine (ALG/PEI)_n/MN was developed for removal of anionic dyes from aqueous solution in this study. (ALG/PEI)_n/MN was prepared by depositing ALG/PEI multi‐layers onto amine‐modified Fe₃O₄ microspheres through layer‐by‐layer method. The morphologies and structures of the adsorbent were characterized by scanning electron microscopy, X‐ray diffractometer, and Fourier transform infrared spectrometer, respectively, and its performance in adsorption of anionic dye (acid orange 10, AO10) under varied experimental conditions were also investigated. The results revealed that the uptake capacity of AO10 by (ALG/PEI)_n/MN increased with the number of coated (ALG/PEI) bilayer on the adsorbents, and the maximum adsorption capacity for AO10 by (ALG/PEI)₄MN was 246.3 mg g^?1 at 25 °C. The adsorption process was exothermic and well described by the pseudo‐second order kinetic model and the Langmuir isothermal model. Moreover, (ALG/PEI)₄/MN showed good reusability and excellent magnetic separability. All the results demonstrate that (ALG/PEI)₄/MN is a potential recyclable adsorbent for removal of anionic dyes from wastewater. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45876.     

Study of electrospinning of sodium alginate,blended solutions of sodium alginate/poly(vinyl alcohol) and sodium alginate/poly(ethylene oxide)

Alginate is an interesting natural biopolymer for many of its merits and good biological properties. This paper investigates the electrospinning of sodium alginate (NaAlg), NaAlg/PVA‐ and NaAlg/PEO‐ blended systems. It was found in this research that although NaAlg can easily be dissolved in water, the aqueous NaAlg solution could not be electrospun into ultrafine nanofibers. To overcome the poor electrospinnability of NaAlg solution, synthetic polymers such as PEO and PVA solutions were blended with NaAlg solution to improve its spinnability. The SEM images of electrospun nanofibers showed that the alginate (2%, w/v)–PVA (8%, w/v) blended system in the volume ratio of 70 : 30 and the alginate (2%, w/v)–PEO (8% w/v) blended system in the volume ratio of 50 : 50 could be electrospun into finest and uniform nanofibers with average diameters of 118.3 nm (diameter distribution, 75.8–204 nm) and 99.1 nm (diameter distribution, 71–122 nm), respectively. Rheological studies showed a strong dependence of spinnability and fiber morphology on solution viscosity and thus on the alginate‐to‐synthetic polymer (PVA or PEO) blend ratios. FTIR studies indicate that there are the hydrogen bonding interactions due to the ether oxygen of PEO (or the hydroxyl groups of PVA) and the hydroxyl groups of NaAlg. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Molecular interactions in poly(methacrylic acid)/poly(N‐isopropyl acrylamide) interpenetrating polymer networks

The molecular interactions between the component networks in poly(methacrylic acid)/poly(N‐isopropyl acrylamide) (PMAA/PNIPAAm) interpenetrating polymer networks (IPNs) were investigated using attenuated total reflectance (ATR)‐Fourier transform IR (FTIR) spectroscopy. Hydrogen‐bond formation was noted between the carboxyl groups of PMAA and the amide groups of PNIPAAm. The ATR‐FTIR results showed shifts in the carboxylic and amide groups, indicating the existence of hydrogen bonding between these two individual networks within the IPNs. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1077–1082, 2001     

Removal of Cr(VI) from aqueous solution using magnetite/non-oxidative graphene composites: Synergetic effect of Cr(VI) on dyes removal

Non-oxidative graphene (nOG) synthesized from natural graphite powder was modified with magnetite (Fe₃O₄) for removal of Cr(VI) and dyes in aqueous solution. The adsorption behavior of Cr(VI) on Fe₃O₄/nOG (M-nOG) was systematically investigated, and the simultaneous adsorption of Cr(VI) and dyes such as methylene blue (MB) and rhodamine B (RhB) was evaluated. Adsorption kinetic and isotherm of Cr(VI) were fitted well with pseudo-second-order model and Sips model, respectively. For the binary system, Cr(VI) removal was not affected with increasing the dye concentration, whereas the adsorption capacity of both MB and RhB was enhanced with increasing the concentrations of Cr(VI).     

High-resolution thermogravimetric analysis of polyurethane/poly(ethyl methacrylate) interpenetrating polymer networks

Thermal degradation of a series of polyurethane/poly(ethyl methacrylate) interpenetrating polymer networks and their constituent networks were studied by three modes of thermogravimetric analysis: the conventional method, the constant reaction rate method, and the dynamic rate technique. The best understanding of the degradation mechanism was achieved by the last method, which allows much better resolution of overlapping events. In addition, the weight losses correspond well with the results obtained from the constant reaction rate analysis, but are achieved in shorter times. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 287–295, 1998     

Second order non-linear optical interpenetrating polymer networks based on polyurethane or poly(methyl methacrylate) and epoxy polymer

Two interpenetrating polymer networks (IPNs), (one pseudo-IPN consisting of a linear polyurethane/epoxy-based polymer network and one full-IPN consisting of a poly(methyl methacrylate)/epoxy-based polymer network) have been synthesized and characterized. Both IPNs showed only one T_g; hence a homogeneous phase morphology is suggested. The second-order non-linear optical coefficients (d₃₃) of the pseudo-IPN and the full-IPN were measured and found to be 2.78 × 10⁻⁷ esu and 1.86 × 10⁷ esu, respectively. The study of temporal stability at room temperature and elevated temperature (120 °C) indicates that the full-IPN is more efficient at improving the orientational stability of the non-linear optical chromophores than the pseudo-IPN, because of the permanent entanglements of the two component networks in the full-IPN. © 1999 Society of Chemical Industry     

New interpenetrating polymer networks based on uralkyd–poly(butyl methacrylate)

A study on two‐component semi‐ and full‐interpenetrating polymer networks (IPNs) of soyabean‐oil based uralkyd resin (UA) and poly(butyl methacrylate) (PBMA) synthesized by a sequential technique, has been conducted. The IPNs obtained are characterized with respect to their mechanical properties, such as tensile strength, percentage elongation and hardness (Shore A). Phase morphology has been studied by scanning electron microscopy. Glass transition studies have been carried out using differential scanning calorimetry. The thermal characterization of the IPNs was undertaken with the aid of thermogravimetric analysis. The apparent densities of these samples have been determined and are compared. The effect of the compositional variation on the above‐mentioned properties was examined. The tensile strength exhibits a sudden rise (approximately three‐fold) for the semi‐ and full‐IPNs with composition UA: PBMA 40% : 60% compared with the UA:PBMA composition of 20% : 40%. © 2001 Society of Chemical Industry     

Synthesis and characterization of konjac glucomannan/poly(vinyl alcohol) interpenetrating polymer networks

Novel interpenetrating polymer networks (IPNs) coded as KP were synthesized successfully from poly(vinyl alcohol) (PVA) and konjac glucomannan (KGM) in the presence of glutaraldehyde as a crosslink agent. The transparent IPN films that were 40 μm thick were prepared by means of conventional solvent‐casting technique and dried at room temperature for 2 days. The structure and miscibility of the KP films were studied by Fourier transformed infrared spectra, scanning electron microscopy, differential scanning calorimetry, wide‐angle X‐ray diffraction, and ultraviolet visible spectroscopy (UV–Vis). The results indicated that strong intermolecular interaction caused by crosslink bonding between PVA and KGM occurred in the IPN films, resulting in wonderful miscibility when the reaction time is 4 h. The tensile strength, elongation at break, and moisture uptake was much higher than that of the pure PVA film, KGM film, and uncrosslinked blend films. In other words, the structure of IPN endowed the films with excellent performance, so the new material has promising applications to food package film and agricultural film because of its biodegradability. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2775–2780, 2004     

Application of nickel (II) complex of dithiocarbamate‐modified starch for anionic dyes removal from aqueous solutions

The work presents the synthesis of nickel (II) complex of dithiocarbamate‐modified starch (DTCSNi). It is characterized by elemental analysis, infrared spectrum, and thermogravimetry methods. A batch system was applied to study the adsorption of DTCSNi for four anionic dyes removals. The adsorption with respect to the pH was investigated. It is found that the capacity of DTCSNi for each dye is pH dependent, and the adsorption is governed by coordination. At the suitable pH 4, two kinetic models, that is, pseudo‐first‐ and pseudo‐second‐order, were tested to investigate the adsorption process. The kinetic parameters of the models were calculated and discussed. The results suggest that the best fit model is the pseudo‐second‐order equation. The Langmuir–Freundlich model agrees very well with experimental data and the maximum adsorption capacity sequence is AO7 > AG25 > AR18 > AO10. The Fourier transform infrared spectra and thermogravimetric analysis verified the chelating molecular mechanism. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Swelling and drug release behavior of calcium alginate/poly (sodium acrylate) hydrogel beads

In the present work calcium alginate/poly (sodium acrylate) composite beads have been prepared by in situ formation of cross-linked poly (sodium acrylate) network, within the calcium alginate (CA) beads. The CA/poly (SA) beads have been found to be stable for more than 48 h, in the physiological fluid (PF) of pH 7.4, while the plain alginate beads disintegrated within a couple of hours. The water uptake of beads was investigated under various composition parameters such as the amount of alginate, concentration of ionic cross-linker Ca⁺⁺ ions, monomer sodium acrylate (SA) contents, and degree of cross-linking. The beads also exhibited fair stability in the media of varying pH. Finally the release of model drug methylene blue (MB) was investigated. It was found that plain CA and CA/poly (SA) composite beads exhibited different release mechanisms.     

Use of amidoximated acrylonitrile/N‐vinyl 2‐pyrrolidone interpenetrating polymer networks for uranyl ion adsorption from aqueous systems

Poly(N‐vinyl 2‐pyrrolidone) (PVP)/acrylonitrile (AN) interpenetrating polymer networks (IPNs) were synthesized and amidoximated for the purpose of uranyl ion adsorption. The adsorption of amidoximated IPNs was studied from different uranyl ion solutions (850, 1000, 1200, 1400, and 1600 ppm). The result of all our adsorption studies showed that the bonding between UO‐amidoxime groups complied with the Langmuir‐type isotherm. The adsorption capacity was found as 0.75 g UO/g dry amidoximated IPN. In order to increase the UO ion adsorption capacity the amidoximated IPN was treated with alkali, but no significant increase could be observed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2324–2329, 2001     

Synthesis and characterization of sequential interpenetrating polymer networks of novolac resin and poly(ethyl acrylate)

Interpenetrating polymer networks (IPN) of Novolac/poly(ethyl acrylate) have been prepared via in situ sequential technique of IPN formation. Both full and semi IPNs were characterized with respect to their mechanical properties that is, ultimate tensile strength (UTS), percentage elongation at break, modulus, and toughness. Physical properties of these were evaluated in terms of hardness, specific gravity, and crosslink density. Thermal behavior was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The morphological features were observed by an optical microscope. There was a gradual decrease in modulus and UTS, with consequent increases in elongation at break and toughness for both types of IPNs with increasing proportions of PEA. An inward shift and lowering (with respect to pure phenolic resin) of the glass transition temperatures of the IPNs with increasing proportions of PEA were observed, thus, indicating a plasticizing influence of PEA on the rigid, brittle, and hard matrix of crosslinked phenolic resin. The TGA thermograms exhibit two‐step degradation patterns. An apparent increase in thermal stability at the initial stages, particularly, at lower temperature regions, was followed by a substantial decrease in thermal stability at the higher temperature region under study. As expected, a gradual decrease in specific gravity and hardness values was observed with increase in PEA incorporation in the IPNs. A steady decrease in crosslink densities with increase in PEA incorporation was quite evident. The surface morphology as revealed by optical microscope clearly indicates two‐phase structures in all the full and semi IPNs, irrespective of acrylic content. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Curing and mechanical properties of dicyanate/poly(ether sulfone) semi‐interpenetrating polymer networks

Semi‐interpenetrating polymer networks (semi‐IPNs) composed of a dicyanate resin and a poly(ether sulfone) (PES) were prepared, and their curing behavior and mechanical properties were investigated. The curing behavior of the dicyanate/PES semi‐IPN systems catalyzed by an organic metal salt was analyzed. Differential scanning calorimetry was used to study the curing behavior of the semi‐IPN systems. The curing rate of the semi‐IPN systems decreased as the PES content increased. An autocatalytic reaction mechanism was used to analyze the curing reaction of the semi‐IPN systems. The glass‐transition temperature of the semi‐IPNs decreased with increasing PES content. The thermal decomposition behavior of the semi‐IPNs was investigated. The morphology of the semi‐IPNs was investigated with scanning electron microscopy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1079–1084, 2003     

Melamine‐based microporous polymer for highly efficient removal of copper(II) from aqueous solution

In this study, we investigated the ability of a melamine‐based microporous polymer network as an adsorbent for removal of copper(II) species from aqueous solutions. A designed Schiff based network (SNW) with high specific surface area was synthesized using melamine and terephthalaldehyde monomers at 180 °C for 3 days followed by a freeze‐drying process. The porous structure of the material was confirmed by SEM analysis and CO₂ adsorption/desorption studies at 77.3 K. The adsorption character of the SNW polymer for various metal salts, namely Pb(II), Fe(II), Hg(II), Zn(II), Ni(II) and Cd(II), was investigated and a specific sorption behaviour against Cu(II) salts was observed. The role of pH and contact time was examined and the highest adsorption capacity for Cu(II) was found as 92% with pH 3.5 at the end of 300 min. As evidenced by XRD and Fourier transform infrared spectral analysis, the sorption mechanism is attributed to the coordination system formed between amino groups in the porous structure and Cu(II) ions. Reusability of the system was also demonstrated by applying four cycles without any significant loss of activity. © 2016 Society of Chemical Industry     

Morphology and thermal and dielectric behavior of cycloaliphatic epoxy/trimethacrylate interpenetrating polymer networks for vacuum‐pressure‐impregnation electrical insulation

Vacuum pressure impregnation has been known as the most advanced impregnation technology that has ever been developed for large and medium high‐voltage electric machines and apparatuses. We developed one new type of vacuum‐pressure‐impregnation resin with excellent properties by means of a novel approach based on in situ sequential interpenetrating polymer networks resulting from the curing of trimethacrylate monomer [trimethylol‐1,1,1‐propane trimethacrylate (TMPTMA)] and cycloaliphatic epoxy resin (CER). In this study, the influence of the concentrations of the components and their microstructures on their thermal and dielectric behaviors were investigated for the cured CER/TMPTMA systems via atomic force microscopy, dynamic mechanical analysis, thermogravimetric analysis, and dielectric analysis. The investigation results show that the addition of TMPTMA to the CER–anhydride system resulted in the formation of a uniform and compact microstructure in the cured epoxy system. This led the cured CER/TMPTMA systems to show much higher moduli in comparison with the pure CER–anhydride system. The thermogravimetric analysis results show that there existed a decreasing tendency in the maximum thermal decomposition rates of the cured CER/TMPTMA systems, which implies that the thermal stability properties improved to some extent. The dielectric analysis results show that the cured CER/TMPTMA systems displayed quite different dielectric behaviors in the wide frequency range 0.01 Hz–1 MHz and in the wide temperature range 27–250°C compared with the cured CER–anhydride system. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008