Study of biomineralization of poly(vinyl alcohol)‐based scaffolds using an alternate soaking approach

The present work adds to the continuing efforts of designing a natural bone‐like structure by synthesizing a semi‐interpenetrating polymer network (IPN) of poly(vinyl alcohol)–poly[(acrylic acid)‐co‐acrylonitrile] and impregnating hydroxyapatite (HAP) into the polymer matrix by an alternate soaking process. The prepared HAP–polymer scaffolds were characterized using techniques like Fourier transform infrared spectroscopy, X‐ray diffraction, differential scanning calorimetry, thermogravimetric analysis and environmental scanning electron microscopy. The biomineralized semi‐IPN was evaluated for water sorption capacity and the data were utilized for calculating network parameters such as average molecular weight between crosslinks (M_c) and crosslink density (q). The impregnated HAP was quantified as a function of the chemical architecture of the semi‐IPN, number of reaction cycles and temperature of the swelling bath. Copyright © 2006 Society of Chemical Industry     

Blood protein adsorption onto a polymeric biomaterial of polyethylene glycol and poly[(2‐hydroxyethyl methacrylate)‐co‐acrylonitrile] and evaluation of in vitro blood compatibility

A semi‐interpenetrating polymer network (semi‐IPN) of polyethylene glycol (PEG) and crosslinked poly[(2‐hydroxyethyl methacrylate)‐co‐acrylonitrile] was prepared and adsorption of bovine serum albumin (BSA) on the IPN surfaces was investigated. The dynamic nature of the adsorption process was studied, and the effects of various experimental factors such as pH and ionic strength on the adsorption isotherms of BSA were investigated. Various kinetic parameters, such as the adsorption coefficient, rate constant for adsorption and penetration rate constants, were calculated. For assessment of in vitro blood compatibility of the IPN surfaces, water sorption, blood clot formation tests and percent hemolysis measurements were performed. Copyright © 2004 Society of Chemical Industry     

Water behavior of poly(vinyl alcohol)/poly(vinylpyrrolidone) interpenetrating polymer network hydrogels

Interpenetrating polymer network (IPN) hydrogels based on poly(vinyl alcohol) and 1‐vinyl‐2‐pyrrolidone were prepared by radical polymerization with 2,2‐dimethoxy‐2‐phenylacetophenone as a photoinitiator and N,N′‐methylenebisacrylamide as a crosslinker. The IPN hydrogels were analyzed for the sorption behavior of water at 35°C and a relative humidity of 95% with a dynamic vapor sorption system, and water diffusion coefficients were calculated. Differential scanning calorimetry was used to quantitatively determine the amounts of freezing and nonfreezing water. The free‐water contents in the IPN hydrogel samples PV51, PV31, and PV11 were 74.40, 64.03, and 60.48% in pure water, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 24–27, 2003     

Synthesis and characterization of interpenetrating polymer network based on sodium alginate and methacrylic acid and potential application for immobilization of TiO2 nanoparticles

An interpenetrating polymer network (IPN) based on the sodium alginate (A) and partially neutralized poly(methacrylic acid) (MAA) was prepared by free radical polymerization followed by additional cross‐linking of sodium alginate with calcium ions. Obtained material (A/MAA IPN) was characterized by FTIR spectroscopy, thermogravimetric analysis, scanning electron microscopy, and rheological measurements. Swelling behavior of synthetized IPN has been also investigated. TiO₂ nanoparticles (TiO₂ NPs) were immobilized onto A/MAA IPN by dip‐coating method and obtained TiO₂/IPN nanocomposite was used for removal of the methylene blue (MB) from aqueous solution. The photodegradation (under illumination) and sorption (in the dark) processes for dye removal were monitored through decrease of dye concentration in the solution by UV/VIS spectrometer. The TiO₂/IPN nanocomposite sorbed approximately 93% of the MB from a 10 mg L^?1 MB solution in the dark, but no degradation occurred. Likewise, more than 93% of dye was removed after 8 h of illumination. However, after 24 h of illumination, the samples were discolored indicating that dye molecules were successfully degraded. Thus, the TiO₂/IPN nanocomposite could be utilized in the photodegradation–sorption process for the abatement of pollutants in water. POLYM. ENG. SCI., 55:2511–2518, 2015. © 2015 Society of Plastics Engineers     

Mechanical and dynamic mechanical studies of epoxy/VAc‐EHA/HMMM IPN–jute composite systems

Epoxy [50:50 mixture of Di‐Glycidyl Ether of Bis‐Phenol A (DGEBA) and Epoxidized Novolac (EPN)] was solution blended with Vinyl Acetate‐2‐ Ethylhexylacrylate (VAc‐EHA) resin in aqueous medium, in varying weight fractions, with Hexamethoxymethylmelamine (HMMM) as a crosslinker and data was compared with a control. The present work was aimed to optimize the tensile strength, dynamic mechanical strength, impact strength, and toughness by preparing a blend followed by jute composites of a semi‐ and full interpenetrating network (IPN). In control experiments epoxy alone was crosslinked (semi‐IPN), whereas the DGEBA‐EPN and VAc‐EHA/HMMM were crosslinked separately (full‐IPN), using jute as the substrate for making composites. Composites of full‐IPN systems of epoxy/VAc‐EHA system had higher moduli and UTS than the semi‐IPN systems. Dynamic mechanical study showed that full‐IPN systems have higher T_g values than semi‐IPN systems. The impact strength increases with increasing proportions of VAc‐EHA copolymer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 958–963, 2004     

Molecular transport of n‐alkanes into PU/PBMA interpenetrating polymer network systems

The methylene diisocyanate (MDI) and toluene diisocyanate (TDI) based polyurethane/polybutyl methacrylate (PU/PBMA‐50/50) interpenetrating polymer network (IPN) membranes have been prepared. The molecular migration of n‐alkane penetrants such as hexane, heptane, octane, nonane, and decane through PU/PBMA (50/50) membranes has been studied at 25, 40, and 60°C using a weight gain method. From the sorption results, diffusion (D) and permeation (P) coefficients of n‐alkane penetrants have been calculated. Molecular migration depends on membrane‐solvent interactions, size of the penetrants, temperature, and availability of free volume within the membrane matrix. Attempts have been made to estimate the parameters of an empirical equation and these data suggest that molecular transport follows Fickian mode. From a study of temperature dependence of transport parameters, activation energy for diffusion (E_D) and permeation (E_P) have been estimated from the Arrhenius relation. Furthermore, sorption results have been interpreted in terms of enthalpy (ΔH) and entropy (ΔS) of sorption. The liquid concentration profiles have been computed using Fick's equation with appropriate initial and boundary conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 739–746, 2003     

Polymeric sodium alginate interpenetrating network beads for the controlled release of chlorpyrifos

Novel polymeric sodium alginate (Na‐Alg) interpenetrating network (IPN) beads have been prepared by crosslinking Na‐Alg blend with gelatin (GE) or egg albumin (EA) using glutaraldehyde (GA) as the crosslinking agent. These beads were used for the controlled release of chlorpyrifos. The swelling experiments were performed in water at different temperatures, and these data were used to calculate the molecular mass (M_C) between crosslinks as well as diffusion coefficients. Diffusion coefficients calculated from desorption data were lower by about two orders of magnitude than those calculated from sorption results. Higher values of M_C were obtained for the gelatin‐based IPNs than the neat Na‐Alg and egg albumin‐based matrices. Size of the beads did not vary significantly either by the network or by increasing the exposure time to the crosslinking agent. The scanning electron microscopy (SEM) was used to understand the surface characteristics of the beads. Differential scanning calorimetry (DSC) indicated a molecular level dispersion of chlorpyrifos in the polymer matrix. The percentage entrapment efficiency showed a dependence on the type of network polymer as well as time of exposure to the crosslinking agent. The encapsulation efficiency decreased with an increase in time of exposure to the crosslinking agent. In vitro release experiments have been performed to follow the release kinetics of chlorpyrifos from the matrices. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 911–918, 2002     

The unique characteristics of water in chitosan–polyether semi‐IPN hydrogel

The state and mobility of water in crosslinked chitosan–polyether semi interpenetrating network (IPN) (cr‐CS–PE semi‐IPN) was studied using differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR), respectively. The effect of water content on free volume for water in gel network was investigated by positron annihilation lifetime spectroscopy (PALS) and its effect on the diffusion coefficient are discussed as well. The results show that with the increase of water content, the mobility of water molecules and the free volume of hydrogel network are enhanced. In the following free‐volume diffusion equation: D = Aexp(−B/V_f), A and B are not constant but are considered as the functions of water contents. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 449–453, 1999     

The swelling behaviors and network parameters of cationic starch‐g‐acrylic acid/poly(dimethyldiallylammonium chloride) semi‐interpenetrating polymer networks hydrogels

Amphiphilic semi‐interpenetrating polymer networks (semi‐IPN) hydrogels were prepared by a sequential‐IPN method by acrylic acid graft copolymerization into cationic starch in mild aqueous media of poly(dimethyldiallylammonium chloride). Some main factors were investigated to evaluate the swelling of hydrogels, and the network parameters M_c were given accordingly to elaborate the interaction between polymers. The chemical structure of the resulting hydrogel was confirmed using Fourier transform infrared spectroscopy. The cationic starch‐based semi‐IPN hydrogels achieved a high swelling capacity of 1070 g/g in deionized water and 94 g/g in 0.9 wt % NaCl solution, respectively) and high compressive stress in a high water content. Besides, a different pH‐dependent behavior was found for this semi‐IPN hydrogel. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characteristics of the interpenetrating polymer network hydrogel composed of chitosan and polyallylamine

A temperature‐ and pH‐dependent hydrogel was studied with interpenetrating polymer network (IPN) hydrogels constructed with water‐insoluble chitosan and polyallylamine. Various IPNs were prepared from different weight ratios of chitosan–polyallylamine. Crosslinked‐IPN hydrogels exhibited relatively high equilibrium water content (EWC) in the range 80–83%. The EWC of IPN hydrogels depended on pH and the amount of complex, which is the content of chitosan and polyallylamine. The differential scanning calorimeter (DSC) thermogram of fully swollen IPN hydrogels appeared between 3 to 4 °C. The IPNs exhibited two glass‐transition temperatures (T_gs), indicating the presence of phase separation in the IPNs as exhibited by dielectric analysis (DEA). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 498–503, 2002     

Properties of interpenetrating polymer network hydrogels composed of poly(vinyl alcohol) and poly(N‐isopropylacrylamide)

Interpenetrating polymer network (IPN) hydrogels based on poly(vinyl alcohol) and poly(N‐isopropylacrylamide) were prepared by the sequential‐IPN method. The IPN hydrogels were analyzed for sorption behavior of water at 35°C and at a relative humidity of 95% using a dynamic vapor sorption system, and water diffusion coefficients were calculated. Differential scanning calorimetry was used for the quantitative determination of the amounts of freezing and nonfreezing water. Free water contents in the IPN hydrogel of IPN1, IPN2, and IPN3 were 45.8, 37.9 and 33.1% in pure water, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2041–2045, 2003     

Thermal,optical, and water sorption properties in composite films of poly(ether imide) and bismaleimides: Effect of chemical structure

Two series of semi‐interpenetrating polymer network (semi‐IPN) composite films, PEI/bismaleimide (UTBM) and PEI/fluorinated BMI (UTFBM) were prepared using a thermoplastic PEI and two different crosslinkable imide moieties. The effects of chemical structure and content of crosslinkable imide moieties on thermal stability, dielectric properties, and water sorption have been investigated. Glass transition temperature and weight loss temperatures increased with increase in the content of crosslinkable imide moieties, indicating the enhanced thermal stability of the semi‐IPN composite films. The refractive indices of the semi‐IPN composite systems increased with increasing crosslinkable imide moieties due to the higher polarizabilities of atoms. The water sorption of the semi‐IPN composite films was significantly decreased by the incorporation of crosslinkable imide moieties, which are interpreted by morphological structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Sorption behavior of water vapor into polyelectrolyte complex of poly(acrylic acid)/poly(4-vinylpyridine)

The sorption of water vapor into the polyelectrolyte complex of poly(acrylic acid)/poly(4-vinylpyridine) has been investigated. The sorption isotherm was evaluated on the basis of various theories; BET equation, Flory–Huggins interaction parameter χ₁, and cluster function G₁₁/v₁. The behavior of the BET plot, χ₁, and G₁₁/v₁ was considered in terms of the structure of the complex, while the crosslink density and charge density were determined from the carbonyl absorption in IR spectra. The reasonable conclusion drawn from the available data is as follows. The interaction of water with specific polymer sites plays an important role in the sorption. The sorbed water plasticizes this material, and it enables the expansion of the network. The large amounts of water incorporated by the expansion cannot be dispersed homogeneously in the network, and indicate clustering tendency.     

Electrical/pH responsive properties of poly(2‐acrylamido‐2‐methylpropane sulfonic acid)/hyaluronic acid hydrogels

Poly(2‐acrylamido‐2‐methylpropane sulfonic acid) (PAMPS)/hyaluronic acid (HA) interpenetrating polymer network (IPN) hydrogels have been prepared by using the sequential‐IPN method. The IPN hydrogels exhibited swelling behavior in solutions at various pHs, in NaCl solutions, and under electrical DC stimulation. The IPN hydrogels were highly swollen in water, but lost much of their water capacity when transferred to solutions having a high ionic strength. The IPN hydrogels showed a significant responsive deswelling in an applied electric field. This behavior indicates the potential application of IPN hydrogels as biomaterials. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1731–1736, 2004     

Preparation and characterizations of interpenetrating polymer network hydrogels of poly(ethylene oxide) and poly(methyl methacrylate)

Interpenetrating polymer network (IPN) hydrogels based on poly(ethylene oxide) and poly(methyl methacrylate) were prepared by radical polymerization using 2,2‐dimethyl‐2‐phenylacetophenone and ethylene glycol dimethacrylate as initiators and crosslinkers, respectively. The IPN hydrogels were analyzed for sorption behavior at 25°C and at a relative humidity of 95% using dynamic vapor sorption. The IPN hydrogels exhibited a relatively high equilibrium water content in the range of 13–68%. The state of water in the swollen IPN hydrogels was investigated using differential scanning calorimetry. The free water in the hydrogels increased as the hydrophilic content increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 258–262, 2003     

Synthesis and characterization of pH‐ and temperature‐sensitive silk sericin/poly(N‐isopropylacrylamide) interpenetrating polymer networks

Interpenetrating polymer networks (IPNs) composed of silk sericin (SS) and poly(N‐isopropylacrylamide) (PNIPAAm) were prepared simultaneously. The properties of the resultant IPN hydrogels were characterized by differential scanning calorimetry and SEM as well as their swelling behavior at various temperatures and pH values. The single glass transition temperature (T_g) presented in the IPN thermograms indicated that SS and PNIPAAm form a miscible pair. The swollen morphology of the IPNs observed by SEM demonstrated that water channels (pores present in SEM micrographs) were distributed homogeneously through out the network membranes. The swelling ratio of the IPNs depended significantly on the composition, temperature and pH of the buffer solutions. The dynamic transport of water into the IPN membrane was analyzed based on the Fickian equation. Copyright © 2006 Society of Chemical Industry     

Preparation of interpenetrating polymer network gel beads for dye absorption

Preparation of interpenetrating polymer network (IPN) gel beads for dye absorption was carried out by using simultaneous crosslinking method. First, sodium alginate (SA), 3‐(methacrylamido) propyl trimethyl ammonium chloride (MAPTAC), and/or acrylamide (AM), K₂S₂O₈, and N,N′‐methylenebisacrylamide (MBAM) were mixed in aqueous solution. The beads were prepared using K₂S₂O₈ and MBAM as the initiator and crosslinking agent, respectively. Then, the solution was dropped into CaCl₂ solution mixed with N,N,N′,N′‐tetramethylethylenediamine (TMEDA). The former was used as the crosslinking agent of alginate and the latter was used as the accelerator for the polymerization of monomer in the alginate solution. The gel bead composed of only alginate was also prepared to compare the properties with IPN gel bead. The components in IPN gel bead were examined by FTIR analysis. The factors effecting the particle size of alginate and IPN gel beads were investigated. In alginate gel bead, the concentration of solution affected the particle size, whereas type of monomer affected the particle size of IPN gel bead. The IPN gel bead had smooth surface (from SEM results), different from the alginate bead. Alginate content caused the swelling behavior of dried IPN beads. Cationic dye was absorbed by crosslinked alginate gel bead. The absorption of reactive dye by IPN gel bead was a result of its cationic charge. The absorption density of IPN gel beads was the reciprocal of the absorbent dosage. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1585–1591, 2006     

Synthesis,characterization, mechanical properties and biocompatibility of interpenetrating polymer network–super‐porous hydrogel containing sodium alginate

In this investigation an interpenetrating polymer network–superporous hydrogel containing sodium alginate (IPN‐SPH_Alg) was synthesized. The morphology of the polymer was characterized using scanning electron microscopy, light images and porosity, and the polymer was further examined by swelling ratio, mechanical strength and biocompatibility. The results indicated that the IPN‐SPH_Alg possessed both large numbers of interconnected pores and an interpenetrating network. The swelling ratio of IPN‐SPH_Alg was lower than that of the superporous hydrogel (SPH) and it decreased as the sodium alginate/monomer ratio increased. The IPN‐SPH_Alg exhibited pH responsiveness and salt‐sensitive properties. Compared to SPH and SPH composites, the mechanical strength of IPN‐SPH_Alg was significantly enhanced. Thiazolyl blue assay on AD293 cells, in situ lactate dehydrogenase assay and morphological study of rat intestine showed that the polymer induced no significant cell or mucosal damage. The fast swelling, good mechanical properties, pH sensitivity and biocompatibility of the IPN‐SPH_Alg suggested it as a potential candidate in the field of drug‐delivery systems. Copyright © 2007 Society of Chemical Industry     

Preparation and characterization of polyvinyl alcohol based biomaterials: Water sorption and in vitro blood compatibility study

Semi‐interpenetrating polymer networks (semi‐IPNs) based on polyvinyl alcohol (PVA) and crosslinked polyacrylamide (PAM) were prepared by redox polymerization and further characterized by FTIR, ESEM, and XRD techniques. The semi‐IPNs of varying compositions were investigated for their water sorption behavior, and the network parameters like average molecular weight between crosslinks (M_C) and crosslink density were evaluated from water imbibition measurements. The semi‐IPNs were also judged for their in vitro blood compatibility by blood clot formation and percent hemolysis test. It was noticed that the chemical architecture exert a profound effect on the over all performance of the biomaterials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2402–2408, 2006     

Recycling of reactive dye using semi‐interpenetrating polymer network from sodium alginate and isopropyl acrylamide

A sequence of semi‐interpenetrating polymer network (semi‐IPN) were synthesized by free radical photo copolymerizing acrylic acid and isopropyl acrylamide (NIPAAm) in aqueous sodium alginate (NaAlg). Their structures (FT‐IR), thermal stability (TG/DTG), morphology (SEM), mechanical properties, reactive blue 4 (RB 4) dye adsorption (624 mg/g) and its dying characteristics, reusability of dye and adsorbent were evaluated. TG thermograms of semi‐IPN in air revealed zero order kinetics for initial step thermal degradation with an activation energy of 68.68 kJ/mol. Dye adsorption showed best fit for Langmuir adsorption isotherm and the kinetics followed pseudo‐second‐order model. The water and dye diffusion kinetics followed non‐Fickian mechanism. The changes in thermodynamic parameters namely Gibbs free energy (ΔG°), entropy (ΔS°) and enthalpy (ΔH°) indicated that the adsorption was spontaneous and exothermic process for RB 4/semi‐IPN system. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40968.