Crosslinked poly(methyl methacrylate) with perfluorocyclobutyl aryl ether moiety as crosslinking unit: thermally stable polymer with high glass transition temperature.

Crosslinked poly(methyl methacrylate) (PMMA) with high glass transition temperature ( T g ) and thermal decomposition temperature was prepared by simple thermal crosslinking of PMMA-containing random copolymers bearing aryl trifluorovinyl ether (TFVE) moieties. A methacrylate monomer consisting of aryl TFVE moiety, 4-((1,2,2-trifluorovinyl)oxy)phenyl methacrylate (TFVOPMA), was first synthesized followed by radical copolymerization with methyl methacrylate (MMA) initiated by AIBN, providing the random copolymer containing aryl TFVE moieties, poly(4-((1,2,2-trifluorovinyl)oxy)phenyl methacrylate)- co -poly(methyl methacrylate) (PTFVOPMA- co -PMMA). Finally, crosslinked PMMA polymer with perfluorocyclobutyl (PFCB) aryl ether moieties as crosslinking units was obtained by [2π + 2π] cycloaddition reaction of aryl TFVE moieties in PTFVOPMA- co -PMMA copolymer. Thermal properties of both PTFVOPMA- co -PMMA and crosslinked PTFVOPMA- co -PMMA were examined by TGA and DSC. Compared to pure PMMA, T g of PTFVOPMA- co -PMMA increased by 15.1 °C and no T g was found in the DCS test of the crosslinked PTFVOPMA- co -PMMA. Thermal decomposition temperature ( T d,5% ) of crosslinked PMMA was 47 °C higher than that of pure PMMA. Furthermore, the water absorption of crosslinked PMMA film greatly reduced in comparison with that of pure PMMA.