New highly fluorinated styrene-based materials with low surface energy prepared by ATRP

2,3,5,6-Tetrafluoro-4-(2,2,3,3,3-pentafluoropropoxy)styrene (TF(F-5)S) and 2,3,5,6-tetrafluoro-4-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctaoxy)styrene (TF(F,5)S) are prepared by nucleophilic substitution of 2,3,4,5,6-pentafluorostyrene. The neat monomers are subjected to atom transfer radical polymerization (ATRP) at 110 degreesC to high conversions in relatively short times, 10-120 min; TF(F-5)S is additionally polymerized at 70 and 90 degreesC.

Block copolymers with styrene are prepared by the macroinitiator approach. All polymers, in the number-average molecular weight range from 6000 to 35 000, have polydispersity indexes between 1.08 and 1.37. The homopolymers show glass transitions from 16 to 62 degreesC depending on molecular weight, whereas the block copolymers exhibit phase separation mirrored in two T(g)s, which could be observed when the smallest block constitutes more than 10 mol %.

The fluorinated side chains of P(TF(F-5)S) and P(TF(F-15)S) enrich the surface of thin films, which results in an advancing water contact angle of 117degrees and 122degrees, respectively. Both XPS analyses and contact angle measurements strongly imply that the fluorinated parts of the block copolymers migrate to the surface and create low surface energy films.