Synthesis and Properties of Gradient Copolymers Based on 2-Phenyl-2-oxazoline and 2-Nonyl-2-oxazoline

In this study, the structure-property relationships for a series of statistical 2-nonyl-2-oxazoline (NonOx) and 2-phenyl-2-oxazoline (PhOx) copolymers were investigated for the first time. The copolymerization kinetics were studied and the reactivity ratios were calculated to be r(NonOx) = 7.1 +/- 1.4 and r(PhOx) = 0.02 +/- 0.1 revealing the formation of gradient copolymers. The synthesis of a systematical series of NonOx-PhOx copolymers is described, whereby the amount of NonOx was increased in steps of 10 mol %. The thermal and surface properties were investigated for this series of well-defined copolymers. The thermal properties revealed a linear decrease in glass transition temperature for copolymers containing up to 39 wt % NonOx. Furthermore, the melting temperature of the copolymers containing 0 to 55 wt % PhOx linearly decreased most likely due to disturbance of the NonOx crystalline domains by incorporation of PhOx in the NonOx part of the copolymer. The surface energies of spincoated polymer films revealed a strong decrease in surface energy upon incorporation of NonOx in the copolymers due to strong phase separation between NonOx and PhOx allowing the NonOx chains to orient to the surface. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6433-6440, 2009