Design, Synthesis, and Film Formation of Fluorine Containing Colloidal Dispersions
Fluoropolymers (FPs) have been subject of interest for many years, however due to extreme synthetic and processing conditions their applications have been limited. This dissertation focuses on design and synthesis of fluorine containing colloidal dispersions to advance limited knowledge and to gain further understanding of fluorine containing colloidal dispersions. Fluoroacrylates and fluoro methacrylates consisting of varying chain length of perfluoroalkyl side chain were copolymerized with methylmethacrylate (MMA) and n-butylacrylate (n-BA) under aqueous environment utilizing phospholipids (PLs) as dispersing agent. Morphologies of colloids, coalescence, and film formation processes after water evaporation was investigated using various microscopic probes such as transmission electron microscope (TEM), atomic force microscopy (AFM), nuclear magnetic resonance (NMR), infrared (IR), and internal reflection infrared imaging (IRIRI). These studies showed that FPs exist as phase-separated domains within colloidal particles leading to unique non-spherical morphologies where blocky phase of FPs exists on the p-MMA/nBA core. Upon coalescence FPs migrates to the film-air (F-A) interface, generating highly hydrophobic and ultra low coefficient of friction surfaces. Further studies focused on utilization of pentafluorostyrene (PFS) as fluorinated component incorporated into p-MMA/nBA colloids, which upon copolymerization with polyethyleneglycol (PEG) molecules leads to surfaces that repel proteins. Copolymerizing PFS in two step synthetic processes, resulted in unique acorn-shaped colloids that consist of two phases p-MMA/nBA and p-nBA/PFS. These acorn-shaped colloids are able to self-assemble which is driven by the surface energies of substrates. For high surface energy substrates, such as glass, fluorinated phase is observed at the F-A interface, but for low surface energy substrates, such as polytetrafluoroethylene (PTFE), hydrogenated phase is exposed at the F-A interface. Using a number of spectroscopic and morphological analytical approaches combined with contact angle analysis as well as thermodynamic modeling aspects of acorn-shaped particles, morphologies and film formations were examined and confirmed the self-assembly of acorn-shaped colloidal particles.