Synthesis and characterization of semi-interpenetrating polymer networks using biocompatible polyurethane and acrylamide monomer

Semi-interpenetrating polymer networks (semi-IPNs) of acrylamide based polyurethanes were synthesized from different NCO-terminated polyurethane prepolymers derived from polytetramethylene ether glycol (PTMEG). The resulting semi-IPNs were characterized using FTIR, DSC, and TGA measurements. Variation in the NCO/OH ratio and the molecular weight of the diol gave semi-IPNs with different types of mechanical characteristics varying from elastomer to brittle plastic properties. Differential scanning calorimetry (DSC) data revealed a difference in the glass transition temperature (T_g) of the semi-IPNs relative to the normal polyacrylamide (PAAM) network. Incorporation of polyurethane into polyacrylamide network in the form of an interpenetrating polymer networks enhanced the mechanical and thermal properties of the semi-IPNs due to higher crosslink density imparted by the hard segment content. The swelling behavior of both the semi-IPNs and the individual polyacrylamide (PAAM) network in different pH conditions were investigated to check their biocompatibility and possible usage in biomedical field. The hydrolytic stability of the semi-IPNs and the polyacrylamide (PAMM) network was studied using phosphate buffer solution. The hydrolytic stability of the semi-IPNs was found to be more compared to PAMM network. The morphology of both the semi-IPNs and the individual polyacrylamide (PAAM) network was investigated using SEM.