Impact of Fluorinated Segment Chemistry on Film Wettability: Comparative Study of Short-Chain Perfluoroalkyl and Perfluoropolyether Structures

Abstract

The transition from long-chain perfluoroalkyl polymers to short-chain perfluoroalkyl and perfluoropolyether (PFPE)-based polymers, driven by health and environmental concerns, has spurred interest in their use as hydrophobic and oleophobic additives. This study explores the influence of fluorinated polyester segment structures on the wettability of polyethylene terephthalate (PET) films. These polyesters with S-PFA backbones and PFPE-based tails (PFocta) were synthesized and incorporated into PET matrices at various concentrations. Additionally, a model fluorinated polyester consisting of a PFPE backbone and identical PFPE tails (P3 polyester) was used for comparison. Surface morphology and wettability of the modified PET films with PFocta were assessed using atomic force microscopy (AFM) and contact angle measurements, respectively. The incorporation of PFocta into PET films significantly enhanced water and oil repellency, underscoring its potential as a surface modifier. Comparative analysis revealed that the backbone structure is a critical determinant of surface properties. PET/PFocta films containing short-chain perfluoroalkyl segments exhibited superior repellency, while those with PFPE segments showed diminished performance due to conformational entropy penalties at the interface. These findings highlight the critical role of backbone architecture in optimizing the performance of fluorinated polyester additives for advanced surface coatings.