Preparation and Swelling Characteristics of Semi-interpenetrating Polymer Networks Composed of Poly(acrylamide-co-acrylic acid)/ Linear Poly(ethyleneimine) or Poly(ethyleneimine)-metal Complexes

Semi-interpenetrating polymeric networks (SIPNs) consisting of poly(acrylamide-co-acrylic acid) p(AAm-AAc) hydrogel matrix and linear polyethyleneimine (LPEI), polymer-metal complexes of LPEI with nickel (LPEI-Ni2+), cobalt (LPEI-Co2+) and zinc ions (LPEI-Zn2+) were prepared by template polymerization: crosslinked AAm-AAc chains were formed in aqueous solution by crosslinking copolymerization of equimolar mixture of AAm and AAc in the presence of N,N-methylenebisacrylamide and LPEI, LPEI-Ni2+, LPEI-Co2+, and LPEI-Zn2+ respectively. The swelling degree of SIPNs in water and swelling kinetics in 0.1N NaOH and 5% NH4OH were determined. The exponential relation Mt/M∞ = ktn (where Mt is the mass of water absorbed at time t and M∞ is the mass of water absorbed at equilibrium) was used for calculation of the exponent (n) describing the mechanism of water transport through these SIPN. The dynamic swelling behavior of SIPNs in alkaline media corresponds to anomalous swelling mechanism