Novel physical hydrogels composed of opened‐ring poly(vinyl pyrrolidone) and chitosan derivatives: Preparation and characterization

A novel, physically stabilized hydrogel system composed of chitosan (Chi) or its derivatives [e.g., carboxymethyl chitosan (CMC), sodium carboxymethyl chitosan, or trimethyl carboxymethyl chitosan (TMCMC)] with poly(vinyl pyrrolidone) (PVP) or opened‐ring poly(vinyl pyrrolidone) (OR–PVP) were prepared and characterized. TMCMC was synthesized by a novel method with dimethylsulfate as the methylation agent. The synthesized materials were characterized by Fourier transform infrared spectroscopy, ¹H‐NMR, ¹³C‐NMR, and size exclusion chromatography. The mechanical properties, gel fraction, swelling behavior, and water state of the prepared hydrogels were investigated. Gelation occurred when the OR–PVP and Chi solutions were blended within a few seconds. However, the gelation of the OR–PVP and CMC solutions needed pH adjustment. No gelation occurred when the solutions of TMCMC and PVP or OR–PVP were blended. The quaternization or protonization of  NH₂ groups may have prevented the gelation of the solutions. The amino groups of Chi derivatives should have been free to take part in hydrophilic bonds between the two polymers. The physical entanglement of polymeric chains and strong hydrogen bonds between the polymers were considered as mechanisms for the formation of the physical hydrogels. The physical hydrogels showed ionic and pH‐sensitive swelling properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Macroporous hydrogels based on chitosan derivatives: Preparation,characterization, and in vitro evaluation

Chitosan‐based hydrogels are considered as promising biomaterials for tissue engineering. Biological properties of chitosan could be significantly improved by modification of its chemical structure. This study was aimed at characterizing macroporous hydrogels fabricated by freeze‐drying technique from chitosan, which has been N‐acetylated by 2,2‐bis(hydroxymethyl)propionic acid or l ,d ‐lactide. The nature of the acetylated agent was shown to significantly affect hydrogels morphology, swelling behavior, zeta‐potential, and protein sorption as well as their degradation by lysozyme. According to scanning electron and confocal laser scanning microscopy, the hydrogels possessed interconnected macroporous network that facilitated cells penetration into the interior regions of the hydrogel. Chemical modification of chitosan significantly influenced L929 cell growth behavior on hydrogel compared to the non‐modified chitosan. The proposed chemical strategy for modification of chitosan could be considered as promising approach for improvement of chitosan hydrogels. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44651.     

Effective removal of a cobalt‐tetrasulfonated phthalocyanine dye from an aqueous solution with a novel modified chitosan‐based superabsorbent hydrogel

Industrial wastewaters from the Merox process are heavily polluted by toxic cobalt‐tetrasulfonated phthalocyanine (CoTsPc) dye catalyst, and in this article, we describe the synthesis of novel chitosan hydrogels and their adsorption capabilities against CoTsPc as biosorbents. In this study, novel chitosan hydrogels were crosslinked by 3,3′,4,4′‐tetracarboxybenzophenone dianhydride and used for the first time. The adsorption capacities of the hydrogels were significantly improved, and they exhibited excellent sorption behavior with ammonium sulfate modification. The adsorption behavior was observed to be pH dependent, and the optimum pH was found to be 8. Moreover, the swelling studies indicated that the hydrogels are superabsorbent. The reusability of these dye‐adsorbent hydrogels was also evaluated. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46167.     

Preparation and properties of crosslinked chitosan thermosensitive hydrogel for injectable drug delivery systems

The aim of this study was to prepare and investigate the physical properties of a thermosensitive crosslinked chitosan pregel solution, and evaluate the in vitro release profiles of macromolecules from this sol–gel transition system. Chitosan and poly (vinyl alcohol) were used to form an interpenetrating polymeric network with glutaraldehyde as the crosslinker, and glycerophosphate (GP) was added to transform the pH‐dependent solutions into thermosensitive pH‐dependent solutions. Rheological study showed that the gelation was dependent on the crosslink degree and GP concentration of the solution. The crosslinked gel had excellent mechanic properties and no apparent “pores” and formed an integrated hydrogel texture according to scanning electronic micrograph. Gas chromatography test guaranteed the medication safety with no detection of glutaraldehyde remnants in the hydrogels. In vitro release study showed that the gelation does not significantly affect the macromolecules diffusion but the crosslinking degree does. These results indicated that the hydrogel formed an intensified three‐dimensional hybrid network with interpenetrating molecules, which effectively buffered or delayed the macromolecules diffusion. The hydrogels sustained the drug release over 30 days and could be potentially used as in situ gelling implants. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1892–1898, 2006     

Reduction of postsurgical adhesion formation with CM‐chitosan hydrogel barriers prepared by using γ‐irradiation

To evaluate the efficiency of carboxymethylchitosan (CM‐chitosan)‐based hydrogels as barriers for reducing postsurgical adhesions, CM‐chitosan was synthesized to simplify the hydrogel‐making process, and the CM‐chitosan solutions were cross‐linked by using γ‐ray irradiation to create the desired hydrogels instead of using chemical cross‐linking reagents. The prepared CM‐chitosan hydrogels were characterized by a FTIR spectroscopy, swelling behavior, gel‐fraction content,and mechanical property such as gel strength of a hydrogel and the results showed a good swelling behavior and mechanical properties. Also, the radiation‐induced CM‐chitosan hydrogels significantly reduced and inhibited the postsurgical adhesions in the rat models. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Frontal polymerization preparation of poly(acrylamide‐co‐acrylic acid)/activated carbon composite hydrogels for dye removal

A series of poly(acrylic acid‐co‐acrylamide) (PAA)/activated carbon (AC) composite hydrogels were rapidly prepared via frontal polymerization (FP). It was found that an increase in the concentration of AC caused an increase in the front velocity (V_f) and the highest front temperature (T_max). It may be attributed to that AC particles could increase the liquid viscosity of reaction mixture and remain the reaction heat during FP. The Fourier transform infrared and scanning electron microscopy (SEM) confirmed that AC particles had entered the hydrogel network, and many spherical AC particles with an average diameter of 0.5–1 μm had been dispersed homogeneously in the PAA hydrogel matrix. The swelling behavior showed that the equilibrium swelling values of hydrogels increased when the concentration of AC particles increased. Adsorption studies showed that incorporation of AC particles into PAA hydrogel matrix could increase the sites of interaction between the hydrogels and crystal violet molecules and result in an increase of adsorption capacities of hydrogels toward dyes. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

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     

Star‐shaped polycaprolactone/chitosan composite hydrogels: fabrication and characterization

Star‐shaped polycaprolactone (stPCL)/chitosan composite hydrogel was fabricated by simply melt/solution blending between chitosan/dicarboxylic acid solution and melted stPCL, using 1‐(3‐dimethylaminopropyl)‐3‐ethylcarbodiimide hydrochloride and N‐hydroxysuccinimide as conjugating agents to obtain a composite hydrogel. Here, stPCL and modified stPCL were investigated. The stPCL was modified to have a carboxyl‐terminated chain (stPCL‐COOH). The composite hydrogels were transparent. The network structure of the composite hydrogels was investigated. stPCL‐OH had no chemical bond to the chitosan network but stPCL‐COOH could co‐crosslink with the chitosan network. The porous structure and porosity of the composite hydrogels were similar to those of chitosan hydrogel. However, the hydrophobicity of stPCL resulted in a lower swelling ratio compared to chitosan hydrogel. The rheological analysis of the composite hydrogel exhibited a stable crosslinked network. Compression testing of the composite hydrogel obtained from stPCL‐COOH at a mole ratio of stPCL‐COOH and chitosan of 1:1 had optimum compressive mechanical properties comparable to chitosan hydrogel due to a synergistic effect of the flexibility in stPCL and the co‐crosslinking of stPCL‐COOH with the chitosan network. © 2020 Society of Chemical Industry     

Removal of cobalt ions from aqueous solutions by using poly(N,N‐dimethylaminopropyl methacrylamide/itaconic acid) hydrogels

In this study, N,N‐dimethylaminopropyl methacrylamide (DMAPMAm) homopolymer and DMAPMAm/itaconic acid (DMAPMAm/IA) copolymers were obtained from ⁶⁰Co‐γ radiation polymerization. Gel fraction and percentage of swelling values were calculated through gravimetrical calculations. In order to increase the swelling of the hydrogel, the amount of IA in initial copolymer composition was gradually increased, but it was observed that gelation values were low. The structural and morphological assessments of homopolymer and copolymers were made by means of several techniques including Fourier Transform Infrared Spectroscopy (FT‐IR), Scanning Electron Microscopy (SEM), and Energy‐Dispersive X‐ray Spectroscopy (EDS). The cobalt ion (Co²⁺) removal capacities of hydrogel were investigated by taking into account of the initial metal ion concentration and pH of aqueous medium. When it came to the maximum capacity of values obtained from adsorption experiments by using Co²⁺ solutions at pH 5, they changed between 220 and 245 mg Co²⁺/g dry hydrogel. FT‐IR, SEM, EDS, and XRD analyses were carried out for enlightening the mechanism of Co²⁺ removal by hydrogels after the completion of adsorption. Also, desorption studies were conducted using ethylenediaminetetraacetic acid (EDTA). Finally, within approximately 5 days, all adsorbed Co²⁺ ions were released from hydrogels at pH 5 using 0.1M EDTA solution. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39569.     

Hydrogel composites with temperature induced phase transition for biocatalysis

BACKGROUND: This paper focuses on the development of temperature induced phase transition hydrogels based on poly(N‐isopropylocrylamide (PNIPA) copolymers and their application as an immobilization matrix for biocatalysts. RESULTS: PNIPA‐co‐AAc and PNIPA‐co‐MAAc hydrogels were synthesized with different comonomer concentrations and analysed. In order to evaluate the capacity of hydrogels to take up or to release liquids the mass exchange capacity is introduced. In the presented work mass exchange capacities up to 22.4 were realized. To enhance the mechanical stability, composites of hydrogels and cellulosic fleeces were prepared. The enzyme Lipozyme ^® TL 100 L (Thermomyces languniosa Lipase) was successfully inserted into the hydrogels and into the hydrogel composites. Lipase‐catalysed transesterification of rapeseed oil with ethanol to the corresponding ethyl ester was investigated to prove the activity of immobilized enzyme and thus, the concept. The activity was found to be similar to that of free enzyme. CONCLUSION: Smart hydrogel composites were used for the transesterification of oil. Based on the results obtained, reversible loadable and mechanical stable hydrogel composites could be developed for continuous working reactor concepts. Copyright © 2010 Society of Chemical Industry     

Effects of chitosan characteristics on the physicochemical properties,antibacterial activity,and cytotoxicity of chitosan/2‐glycerophosphate/nanosilver hydrogels

The effects of molecular weight (MW) and the degree of deacetylation (DD) of chitosan (CS) on the physicochemical properties, antibacterial activity, and cytotoxicity of CS/2‐glycerophosphate (GP)/nanosilver hydrogel in the development of a thermosensitive in situ formed wound dressing are examined herein. The gelation temperatures for the hydrogels were measured in the range of 32–37°C by manipulating the MW and DD of CS and the GP concentration. The structure of 88% DD CS hydrogel was more porous, uniform, and connective than that of the 80% DD CS hydrogel. The superior water vapor transmission rates of hydrogels with 80% and 88% DD CS were 7150 ± 52 and 9044 ± 221 gm^?2 d^?1, respectively. The skin permeations of nanosilver by the 80% and 88% DD CS hydrogels were 3.82 and 4.99 μg cm^?2, respectively, in 24 h tests. Both the hydrogels with 6 and 12 ppm nanosilver showed cytotoxicity for HS68 cells. The diameters of the hydrogel's inhibition zones for Pseudomonas aeruginosa and Staphylococcus aureus increased when the concentration of nanosilver increased and the MW of the CS decreased. Therefore, the hydrogel could be prepared with lower MW CS and lower concentration of nanosilver in order to reduce the cytotoxicity of nanosilver, while maintaining similar antibacterial activity for a hydrogel prepared with higher concentration nanosilver and higher MW CS. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Polymeric hydrogels obtained using a redox initiator: Application in Cu(II) ions removal from aqueous solutions

Poly(acrylic acid‐co‐acrylamide) hydrogels were prepared via free‐radical solution polymerization, crosslinked with ethylene‐glycol‐dimethacrylate, potassium persulfate/ammonium bisulfite as the initiator, and applied in the removal of Cu(II) ions from aqueous solutions. Molar ratios of acrylamide/acrylic acid moieties and the amount of crosslinking agent were varied to determine the swelling capacities of hydrogels and maximum metal uptake. Polymerization kinetics was investigated by ¹H‐NMR. Hydrogel physicochemical properties were characterized by nitrogen sorption measurements, elemental analysis, FTIR, and X‐ray photoelectron spectroscopy (XPS). Swelling results indicated that hydrogels were swollen up to 27,500%. Hydrogels showed equilibrium Cu(II) adsorption capacities of 211.7 mg g^?1 and fast kinetics (～20 min). Langmuir isotherm fitted adsorption equilibrium data. FTIR and XPS results helped in elucidating the presence of monodentate copper complex on the surface of hydrogels. A simple synthesis route of hydrogels using the redox initiator suggests the potential application in the removal of toxic metals from aqueous streams. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39933.     

Cu2+ removal from aqueous solution by modified chitosan hydrogels

BACKGROUND: The adsorption of Cu²⁺ from aqueous solution using crosslinked chitosan hydrogels impregnated with Congo Red (CR) by ion‐imprint technology was systematically investigated with particular reference to the effects of contact time, pH, and initial concentration on adsorption. RESULTS: The adsorption capacity of the crosslinked chitosan without impregnation was only 68.68 mg g^?1 for Cu²⁺. However, the adsorption capacity increased from 77.42 (without imprint ion) to 84.54 mg g^?1 (imprint ion content 0.5 mmol) after the chitosan was impregnated with a ratio of 1/12 of CR to chitosan. The as‐prepared adsorbents were found to be pH‐dependent and the process of adsorption agreed well with the Freundlich isotherm. The loaded adsorbents could be regenerated and reused without the appreciable loss of capacity. CONCLUSION: Chitosan hydrogels impregnated with CR showed higher Cu²⁺ adsorption capacities compared with those prepared conventionally without imprint ion, and thus developed a good approach to increase Cu²⁺ adsorption efficiency in the treatment of waste‐water. Copyright © 2012 Society of Chemical Industry     

Alcohol-triggered silk fibroin hydrogels having random coil and β-turn structures enhanced for cytocompatible cell response

Alcohol additive is one of the stimulants that induces the fast gelation of silk fibroin solution. Based on our previous report, different alcohol types influence the gelation kinetic and the properties of resulting silk fibroin hydrogels. Here, the effects of alcohol concentrations on the silk fibroin gelation and cell response were reported. All fibroin hydrogels prepared with various alcohol additives showed cell biocompatibility, especially the fibroin hydrogel prepared with 10 wt % n-butanol. Results on the mechanical properties of hydrogels, n-butanol additive enhanced a higher compressive modulus up to ~ 22 times in comparison to non-alcoholic fibroin hydrogel. Fourier transform infrared analysis and peak deconvolution showed a possible formation of more β-turn linkage and random coil structure of fibroin segments in alcoholic fibroin hydrogel. So, the micro-segmental structure of fibroin hydrogel caused the higher compressive modulus, prolonged deformation of the hydrogels, and efficient cell growth on the fibroin hydrogel. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48731.     

Electrical behavior of chitosan and poly(hydroxyethyl methacrylate) hydrogel in the contact system

Semi‐interpenetrating polymer networks (semi‐IPNs), as polymer hydrogels composed of chitosan and poly(hydroxyethyl methacrylate) (PHEMA), exhibiting electrical‐sensitive behavior, were prepared. The swelling behavior of the chitosan/PHEMA hydrogels was studied by immersing the gels in various concentrations of aqueous NaCl solution. The electrical responses of the semi‐IPN hydrogel, in applied electric fields, were also investigated. When the semi‐IPN hydrogels were swollen, where one electrode was placed in contact with the gel and the other fixed 30 mm apart from one, they exhibited bending behavior on the application of an electric field on a contact system. The electroresponsive behavior of the present semi‐IPN was also affected by the electrolyte concentration of the external solution. The semi‐IPN also showed various degrees of increased bending behavior depending on the electric stimulus. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 915–919, 2004     

Rheometric study of chitosan/activated carbon composite hydrogels for medical applications using an experimental design

Composite chitosan/activated carbon hydrogels were prepared with the vapor‐induced phase separation process. A rheometric study was performed with a factorial fractional design to determine the formulation and process parameters significantly influencing the mechanical properties of the gels. The results revealed that three factors played a key role in the storage modulus of the gels. According to the model, these factors could be classified with respect to their relative influence on the storage modulus in the following descending order: chitosan concentration > gel time of exposure to ammonia vapors > temperature of the reactor. Increasing these parameters led to an increase in the physical crosslinking density within the matrices and resulted in a reinforcement of the mechanical properties of the hydrogels. Two interactions were also shown to be significant and promoted the formation of supplementary junction zones within the matrix: the first one corresponded to the interaction between the chitosan concentration and the exposure time to ammonia vapors, and the second one concerned the interaction between the chitosan concentration and the temperature of the reactor. A second‐order model was obtained from statistical analysis. Because of the determination coefficient (89.4%) and the P value related to the lack of adjustment of the model (0.043), which was associated with a 95% confidence level, this model could be considered to be of good quality. Three gels were used to validate the model, and good accuracy was obtained. The maximum elastic modulus was obtained with the highest chitosan concentration [4% (w/v)], the highest temperature in the gelation chamber (50°C), and the longest time of exposure to ammonia vapors (24 h). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Enhancing the crystallization and orientation of electrospinning poly (lactic acid) (PLLA) by combining with additives

Novel hydrogel films composed of hydroxyethylacryl chitosan (HC) and sodium alginate (SA) were prepared for biomedical application by using calcium chloride (CaCl₂) as a nontoxic ionic crosslinker to form a semi-interpenetrating polymer network (semi-IPN). HC was successfully prepared by following a Michael addition reaction of chitosan (CS) and hydroxyethylacrylate completely dissolved in distilled water at 70 °C. The distribution pattern of Ca²⁺ ions were well-dispersed within the hydrogel films examined by scanning electron microscope-energy dispersive spectrometry (SEM-EDS), implying uniformity of crosslinking. The swelling behavior of the hydrogel films in distilled water, simulated gastric fluid (SGF, pH?=?1.2) and phosphate buffer solution (PBS, pH?=?7.4) were investigated. The equilibrium swelling degree of the hydrogel films in distilled water increased with a decreas of either the SA content or the concentration of CaCl₂. The hydrogel films showed pH-dependent behavior in that the shapes of the hydrogel films were stable in SGF while they degraded in PBS. The tensile strength and elongation of the hydrogel films reached 12.1 MPa and 162%, respectively, which presented reasonable mechanical properties during use and enough flexibility to follow skin movement. Cell viability of the hydrogels was measured using a methylthiazol tetrazolium (MTT) assay. The results indicated that the hydrogel films are not cytotoxic.     

Behaviors of polyelectrolyte AAm/AMPS/bentonite composite hydrogels in uptake of uranyl ions from aqueous solutions

Uranyl ion (UO₂²⁺) sorption properties of polyelectrolyte composite hydrogels made by the polymerization of acrylamide (AAm) with 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS) and clay such as bentonite (Bent) were investigated as a function of composition to find materials with swelling and uranyl ion sorption properties. Highly swollen AAm/AMPS hydrogels and AAm/AMPS/Bent composite hydrogels were prepared by free radical solution polymerization in aqueous solutions of AAm with AMPS as co‐monomer and two multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and 1,4 butanediol dimethacrylate (BDMA). Swelling experiments were performed in water at 25°C, gravimetrically. The influence of AMPS content in hydrogels was examined. Uranyl ion adsorption from aqueous solutions was studied by batch sorption technique at 25°C. The effect of uranyl ion concentration and mass of AMPS on the uranyl ion adsorption were examined. Finally, adsorption capacity (the amount of sorbed uranyl ion per gram of dry hydrogel) (q) was calculated to be 0.67 × 10⁻³–2.11 × 10⁻³ mol uranyl ion per gram for the hydrogels. Removal effiency of uranyl ions (RE%) was changed range 9.05–29.92%. The values of partition ratio (K_d) of uranyl ions was calculated to be 0.10–0.43 for AAm/AMPS hydrogels and AAm/AMPS/Bent composite hydrogels, respectively. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Selected properties of pH‐sensitive,biodegradable chitosan–poly(vinyl alcohol) hydrogel

Chitosan and poly(vinyl alcohol) (PVA) were used to form a semi‐interpenetrating polymeric network with glutaraldehyde as the cross‐linker. The molecular weight and degree of deacetylation of the chitosan were 612 kDa and 72 %, respectively. The chemical bonds formed by the cross‐linking reaction and transition of these bonds in different pH media were investigated. The gelation property of the chitosan–PVA pregel solution and mechanical properties of the hydrogel were studied. The FTIR spectra of the hydrogel before and after swelling at pH 3 and pH 7 indicated formation of Schiff's base (C?N) and ? NH₃⁺. They also showed pH‐induced transition of C?N to C? N, and ? NH₃⁺ to ? NH₂, as well as the instability of the Schiff's base. The chitosan is essential for hydrogel formation through Schiff's base reaction between the amino groups of the chitosan and the aldehyde groups of the glutaraldehyde. The addition of PVA improved the mechanical properties of the hydrogel. However, PVA tends to leach out at longer swelling times in the acidic medium due to hydrolysis of the gel networks, Schiff's base. Copyright © 2004 Society of Chemical Industry     

Electric stimuli responses to poly(vinyl alcohol)/chitosan interpenetrating polymer network hydrogel in NaCl solutions

An interpenetrating polymer network (IPN) hydrogel composed of poly(vinyl alcohol) (PVA) and chitosan exhibited electric‐sensitive behavior. The PVA/chitosan IPN hydrogel was synthesized by an ultraviolet (UV) irradiation method that is used in several biomedical and industrial fields. The swelling behavior of the PVA/chitosan IPN hydrogel was studied by immersion of the gel in NaCl aqueous solutions at various concentrations. The swelling ratio decreased with increasing concentration of NaCl solution. The stimuli response of the IPN hydrogel in electric fields was also investigated. When a swollen PVA/chitosan IPN was placed between a pair of electrodes, the IPN exhibited bending behavior in response to the applied electric field. The bending angle and the bending speed of the PVA/chitosan IPN increased with increasing applied voltage and concentration of NaCl aqueous solution. The PVA/chitosan IPN also showed stepwise bending behavior depending on the electric stimulus. In addition, thermal properties of PVA/chitosan IPN were investigated by differential scanning calorimetry (DSC) and dielectric analysis (DEA). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2285–2289, 2002