Surface segregation in end fluorinated polystyrenes

Surface segregation effects in a neat system of perfluorinated polystyrenes were investigated using contact angle analysis. Surface composition and surface energies for a homologous series of samples ranging in molecular weight from 5000 g/mol to 100,000 g/mol were determined. The surface enrichment of end groups was found to decrease with increasing molecular weight of PS-F. Calculations show that for the 5000 g/mol PS-F the surface tension was 19.9 mN/m, a massive reduction from 32.4 mN/m for non functional PS and approaching that of PTFE at 18.2 mN/m. The 100,000 PS-F had a surface tension of 29.7 mN/m, an 8% decrease from the non functional polymer for a 0.1% concentration of fluorinated end groups. The molecular weight dependence of polymer surface tension will be compared with theoretical predictions.