Synthesis and properties of copolymers of methyl methacrylate with 2,3,4,5,6-pentafluoro and 4-trifluoromethyl 2,3,5,6-tetrafluoro styrenes: An intrachain interaction between methyl ester and fluoro aromatic moieties

Abstract

2,3,4,5,6-Pentafluoro and 4-trifluoromethyl 2,3,5,6-tetrafluoro styrenes were readily copolymerized with methyl methacrylate (MMA) by a free radical initiator. The copolymers were soluble in tetrahydrofuran and acetone. The films obtained were transparent and flexible. The glass transition temperatures (T g S) of the copolymers were found positively deviated from the Gordon-Taylor equation. The positive deviation could be accounted for by dipole-dipole intrachain interaction between the methyl ester group of MMA and the highly fluorinated aromatic moiety, which resulted in a decrease in the segmental mobility of the polymer chains and the enhanced T g values of the copolymers. The water absorption of PMMA was greatly decreased by copolymerization of MMA with the highly fluorinated styrenes. With as little as 10 mol % of pentafluoro styrene content in the copolymer, the water absorption was decreased to one-third of that for pure PMMA. The fluorinated styrenes-MMA copolymers were thermally stable up to 420 °C under air and nitrogen atmospheres. With 50 mol % of MMA in the copolymer, the copolymer was still stable up to 350 °C. Since these copolymers contain a large number of fluorine atoms, the light absorption in the region of the visible to near infrared is decreased in comparison with non-fluorinated polymers. Thus, these copolymers may be suitable for application in optical devices, such as optical fibers and waveguides.