Pradeep K. Rana

Interpenetrating Polymer Network PVA/PAA Hydrogels

ABSTRACT A new type of interpenetrating polymer network (IPN) hydrogel based on polyvinyl alcohol (PVA) networking with difuctional monomer, acrylic acid (AA), and its polymer, polyacrylic acid (PAA), generated in situ, were prepared by a non-conventional emulsion method without any added crosslinker, using benzoyl peroxide as initiator and sodium chloride as additive. Structure and bonding in hydrogel due to interpenetrating network were confirmed by infrared spectroscopy. The networking was optimized by variation of reaction parameters such as concentrations of additive, monomer, time, and temperature. The response of the hydrogels with and without NaCl was observed by study of their swelling kinetics, and their apparent activation energies for diffusion (Ed) of water were calculated to be 29.28 and 35.97 J mol−1 K−1 with and without NaCl, respectively. The conductivity and pH were measured at different temperatures. The conductivity decreased largely with temperature whereas pH increased in presence of NaCl. The effect of swelling ratio was studied by variation of AA percentage and the optimal PVA/AA was determined. Biodegradability of the polymeric network was studied by culture media and the surface morphology investigated by scanning electron microscopy (SEM).

Potential Advantages of Poly(Acrylonitrile-co-methyl acrylate)/ Sodium Silicate Nanocomposites over P(AN-co-MA) Copolymer

Poly (acrylonitrile-co-methyl acrylate) copolymer and P(AN-co-MA)/sodium silicate (SS) nanocomposite were synthesized via non-conventional emulsion method using an in situ transition metal complex Co(II)/EDTA and ammonium persulfate (APS) as initiator. The copolymer and nanocomposite so obtained were characterized and the results were compared. UV-visible spectral analysis revealed various interactions between the in situ complex and other reaction components. Infrared and 1H NMR spectra confirmed the formation of the P(AN-co-MA) copolymer and P(AN-co-MA)/SS nanocomposite. Furthermore, as evidenced by transmission electron microscopy (TEM), the composite obtained was found to have nano scale structure. X-ray diffraction (XRD) studies were carried out to analyze the aqueous dispersions of silicate with monomers, initiators, and monomers with initiators. For P(AN-co-MA) copolymer and P(AN-co-MA)/SS nanocomposite, XRD results confirmed that the silicate layers were exfoliated in the copolymer matrix during the polymerization process. An increase in the thermal stability for the nanocomposite was recorded by thermo gravimetric analysis (TGA). In comparison with the P(AN-co-MA) copolymer, the new P(AN-co-MA)/SS nanocomposite was found to show super absorbency and was biodegradable when tested by soil burial, activated sludge and cultured media and further confirmed by scanning electron microscopy (SEM).