Complementary characterization by fluorescence and AFM of polyaminosiloxane glass fibers coatings

Abstract

AR-Glass fibers were coated with the coupling agent 3-aminopropyltriethoxysilane. The polyaminosiloxane coating obtained was characterized: (i) at a molecular scale by using the fluorescence response of pyrene moiety chemically attached (PSA) to the polymer coating and (ii) at a nanoscopic scale by using Atomic Force Microscopy (AFM). After modifying the polymer structure of the coating by the action of different solvents, the data obtained from both techniques were jointly discussed. It was confirmed by AFM that the deposition of the coupling agent on the fibers is in the form of homogeneously distributed ‘islands’. Furthermore, differences in the size of the silane islands were observed when the silanized fibers are subjected to the effect of different solvents. The fluorescence emission from PSA showed that the solvents exert an important structural change in the polyaminosiloxane coating. The correlation between information at a nanoscopic scale (morphology) and at molecular scale (structure) suggested that certain solvents under a subsequent specific evaporation rate rearrange the polymer chains of the glass fibers coating. This rearrangement seems to be a kind of solvophobic effect whose degree depends on the quality of the solvent and the evaporation rate.