Fluorinated Organosilicon Oligomers with End Groups Capable of Further Polycondensation

Abstract

It has been established that radical polymerization of tetrafluoroethylene (TFE) in liquid alkoxysilanes (dimethyldimethoxy, trimethoxy, methyltrimethoxy, or tetramethoxysilane) yields fluorinated organosilicon oligomers with the general formula R(C₂F₄)_nH, where RH is an alkoxysilane molecule capable of further polycondensation. The composition of the terminal groups and the molecular-mass distribution of the oligomers have been determined from mass spectra, NMR spectra, and differential thermogravimetric curves. With increasing TFE concentration in solutions, the chain growth is accompanied by a transition from a homogeneous to a colloidal solution and then to a gel of oligomers. At maximum TFE concentrations, the chain length n in colloidal solutions reaches 10–12. The colloidal particles are composed of oligomers and solvent molecules, the number of which per one monomer unit is minimal in the gel to be 4–6. On the basis of the oligomers obtained, it is feasible to create coatings having both high hydrophobicity and strong bonding with the protected surface.