Copolymers of methyl methacrylate and fluoroalkyl methacrylates: Effects of fluoroalkyl groups on the thermal and optical properties of the copolymers

Fluoroalkyl methacrylates, 2,2,2-trifluoroethyl methacrylate (1), hexafluoroisopropyl methacrylate (2), 1,1,1,3,3,3-hexafluoro-2-methyl-2-propyl methacrylate (3), and perfluoro t-butyl methacrylate (4) were synthesized. Homopolymers and copolymers of these fluoroalkyl methacrylates with methyl methacrylate (MMA) were prepared and characterized. With the exception of the copolymers of MMA and 2,2,2-trifluoroethyl methacrylate (1), the glass transition temperatures (T(g)s) of the copolymers were found to deviate positively from the Gordon-Taylor equation. The positive deviation from the Gordon-Taylor equation could be accounted for by the dipole-dipole intrachain interaction between the methyl ester group and the fluoroalkyl. ester group of the monomer units. These T-g values of the copolymers were found to fit with the Schneider equation. The fitting parameters in the Schneider equation were calculated, and R-2 values, the coefficients of determination, were almost 1.0. The refractive indices of the copolymers, measured at 532, 633, and 839 nm wavelengths, were lower than that of PMMA and showed a linear relationship with monomer composition in the copolymers. 2 and MMA have a tendency to polymerize in an alternating uniform monomer composition, resulting in less light scattering. This result suggests that the copolymer prepared with an equal molar ratio of 2 and MAM may have useful properties with applications in optical devices. (C) 2008 Wiley Periodicals, Inc.