Comparative studies on miscibility and phase behavior of linear and star poly(2-methyl-2-oxazoline) blends with poly(vinylidene fluoride)

The comparative studies on the miscibility and phase behavior between the blends of linear and star-shaped poly(2-methyl-2-oxazoline) with poly(vinylidene fluoride) (PVDF) were carried out in this work. The linear poly(2-methyl-2-oxazoline) was synthesized by the ring opening polymerization of 2-methyl-2-oxazoline in the presence of methyl p-toluenesulfonate (MeOTs) whereas the star-shaped poly(2-methyl-2-oxazoline) was synthesized with octa(3-iodopropyl) polyhedral oligomeric silsesquioxane [(IC 3 H 6 ) 8 Si 8 O 12 , OipPOSS] as an octafunctional initiator. The polymers with different topological structures were characterized by means of Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. It is found that the star-shaped poly(2-methyl-2-oxazoline) was miscible with poly(vinylidene fluoride) (PVDF), which was evidenced by single glass-transition temperature behavior and the equilibrium melting-point depression. Nonetheless, the blends of linear poly(2-methyl-2-oxazoline) with PVDF were phase-separated. The difference in miscibility was ascribed to the topological effect of PMOx macromolecules on the miscibility.