In order to obtain thermal-stable, low birefringent, and low optical loss waveguiding materials, we synthesized several fluorinated poly(maleimide-co-glycidylmethacrylate)s using a pentafluorophenylmaleimide (PFM) and two kinds of methacrylate derivatives as comonomers and glycidylmethacrylate as a crosslinker.
One comonomer is a linear fluorinated methacrylate (HFBM) and another is a bulky norbornane-derived methacrylate (NMMA).
These copolymers could be self-crosslinked by heating due to epoxy groups of glycidylmethacrylates.
As a maleimide contents increased to 50 mol%, these copolymers showed high decomposition temperatures of above 300oC.
The refractive index could be precisely controlled by the variation of PFM/HFBA or PFM/NMMA feed ratio in the range of 1.410~1.508 at 643 nm.
The copolymers had very low birefringence in the range of 1~5
10-4.