Mechanical and thermal properties of perfluoroalkyl ethyl methacrylate–methyl methacrylate statistical copolymers synthesized in supercritical carbon dioxide

Poly(methyl methacrylate-ran-perfluoroalkyl ethyl methacrylate) copolymers having varying perfluoroalkyl ethyl methacrylate ester (Zonyl-TM) contents were synthesized in supercritical CO2. Complete amorphous structures of the copolymers were verified by XRD. Young's modulus (Ymod) of the copolymers was decreased linearly from 1.57 to 1.08 GPa and Tg values from 102 to 77 °C with the increase of Zonyl-TM content. A linear relationship between the Ymod and the Tg values of the copolymer was also found. The increase of the large branched pendant groups resulted in the increase of the free volume and a corresponding decrease in Ymod and Tg of the copolymers. A good fit was found when the Schneider equation was used. Negative deviation from the Gordon–Taylor equation was observed when Zonyl-TM content was lower than 14% due to rapid increase in free volume and then a positive deviation was found due to the dipole–dipole interactions between the methyl ester and fluoroalkyl ester groups.

Increase in the perfluoro ethyl methacrylate content with methyl methacrylate comonomer feed resulted in decrease in the both of glass transition temperature and Young's modulus of the copolymers.Figure optionsDownload as PowerPoint slideHighlights
► Completely amorphous random copolymers of perfluoro ethyl methacrylate with methyl methacrylate were synthesized in scCO2.
► Tg and Ymod values of the copolymers changed as a function of perfluoro ethyl methacrylate content and corresponding free volume.
► Experimental Tg values deviated from the classical Gordon–Taylor equation, however Schneider equation fitted the copolymer Tg values as a function of the perfluoro ethyl methacrylate content.