Investigation of the physical properties of poly(ortho- and para-trifluoromethoxy styrenes)

Ortho and para -OCF₃ substituted styrenes are prepared by the Grignard cross-coupling reaction between -OCF₃ substituted bromobenzene and vinyl bromide and further polymerized in bulk using benzoyl peroxide. The glass-transition temperatures (T_g) are 80 °C and 73 °C for the ortho and para -OCF₃ substituted polystyrenes, respectively, which are much lower compared with polystyrene (100 °C). The size of the -OCF₃ group is large and the ether bond is flexible; thus, the -OCF₃ substituted polystyrenes have larger free volumes, which has more effect on the T_g value compared with that of the steric hindrance effect. The refractive indices are 1.4908 and 1.4809 at 650 nm for ortho and para -OCF₃ substituted polystyrenes, respectively, which are much lower than that of polystyrene (1.5861) due to the presence of fluorine atoms in the polymer unit.