Investigating the effect of grafting density on the surface properties for sequence-determined fluoropolymer films

Abstract

Polymer properties are usually affected by both the chain structure and aggregate structure. This has impeded studies of the relationship between the chain structure and polymer properties. However, for surface properties, the chain structure revealed a significant influence, as the chains are simply arranged as thin layers on the surface. Hence, a controlled chain structure is important to the film surface. Herein, sequence-determined fluoropolymers were synthesized using living anionic polymerization and an epoxy-amine reaction. They had definite perfluoroalkyl chain lengths and a determined sequence distribution (i.e. statistical average distribution). Based on these well-prepared fluoropolymers, the structure–property relationship was studied in detail. This indicated that the long perfluoroalkyl chain led to a low surface tension and slight surface reconstruction; meanwhile, the sequence distribution affected the sensitivity of the structural changes and the surface reconstruction. Finally, based on molecular dynamic simulations and X-ray photoelectron spectroscopy (XPS) analysis, four assembled structural models, called cluster models, were proposed to describe the assembled behaviours of the perfluoroalkyl chains at the surface.