A novel simultaneous semi-interpenetrating polymer network of crosslinked poly(methyl methacrylate) and poly(2-benzyl-2-oxazoline)

The simultaneous cationic, ring-opening polymerization of 2-benzyl-2-oxazoline (BOX) with methyl tosylate in the presence of free-radical (benzoyl peroxide) initiated polymerization of methyl methacrylate (MMA), using ethylene glycol dimethacrylate (EGDMA) crosslinker produced transparent semi-interpenetrating polymer networks (semi-IPNs) with one glass transition temperature (T-g), as shown by differential scanning calorimetry (DSC). The MMA/BOX ratios evaluated in the study were 70/30, 50/50, and 30/70. The simultaneous, free-radical, and cationic polymerization of MMA and 2-benzyl-2-oxazoline mixtures, without EGDMA and over the same monomer mixture ratio range, produced opaque plastics with two T-g values, with both the PMMA and PBOX homopolymers soluble. The T-g values of the two separated linear polymers were close to those previously reported for the two polymers. Over the monomers mixture range examined, the results clearly show that the simple blend of the PBOX and PMMA polymers are immiscible and that the PBOX/MMA polymers are miscible in the semi-IPN systems. Along with providing a new direction for IPN studies, the novel semi-IPNs of the type described may have utility in a variety of applications.