Crosslinking polymerization leading to interpenetrating polymer network formation.: II.: Polyaddition crosslinking reactions of poly(methyl methacrylate-co-2-methacryloyloxyethyl isocyanate) with various diols

As part of our continuing studies concerned with the elucidation of the crosslinking polymerization mechanism leading to interpenetrating polymer network (IPN) formation, in which IPNs consist of both polymethacrylates and polyurethane (PU) networks, this article explores the polyaddition crosslinking reactions of multifunctional poly(methyl methacrylate-co-2-methacryloyloxyethyl isocyanate) [poly(MMA-co-MOI)] [MMA/MOI = 90/10] with various diols leading to PU network formation. Thus, the equimolar polyaddition crosslinking reactions of poly(MMA-co-MOI) with ethylene glycol (EG), 1,6-hexane diol, and 1,10-decane diol (DD) were carried out in N-methyl pyrrolidone at a 0.25 mol/L isocyanate group concentration at 80 degreesC. The second-order rate constants decreased from EG to DD. The deviation of the actual gel point from the theoretical one was smaller from EG to DD. The intrinsic viscosity of resulting prepolymer demonstrated almost no variation with progressing polymerization for the EG system, whereas it gradually increased with conversion for the DD system. Close to the gel point conversion it increased rather drastically for both systems. The swelling ratio of resulting gel was higher from EG to DD. These are discussed mechanistically in terms of the significant occurrence of intramolecular cyclization and intramolecular crosslinking reactions leading to shrinkage of the molecular size. (C) 2003 Wiley Periodicals, Inc.