Electrografting of thiophene, carbazole, pyrrole and their copolymers ontocarbon fibers: electrokinetic measurements, surface composition and morphology

In order to improve the surface properties of carbon fiber without affectin g the mechanical properties of the reinforcing fibers, various monomers (py rrole (Py), carbazole (Cz) and thiophene (Th)) were used to electrograft co njugated copolymers. The electrocoated carbon fibers were characterized wit h respect to their surface morphology and surface composition, using scanni ng electron microscopy (SEM) and FTIR-reflectance spectroscopy, respectivel y. In general very homogeneous and continuous coated carbon fiber surfaces were obtained. The pH-dependent zeta (zeta)-potential measurements were app lied to characterize the surface properties of all electrocoated fibers. Th e performed zeta -potential measurements reflect that the surface state is strongly dependent not only on the composition of the grafted polymers (dif ferent homopolymers, copolymers and a single terpolymer). but also on the e xtent of doping by the counter ion from the supporting electrolyte. Polymers or copolymers formed in solution during the electrografting proces s were also analyzed using FTIR-reflectance, H-1 NMR and UV-VIS spectroscop y, as well by gel permeation chromatography (GPC) and elemental analysis. Such a detailed investigation of well known electrografted copolymers opens the possibility to use such 'superior' materials in the field of carbon fi ber reinforced polymeric composite materials. The main advantages of such h omogeneous and dense clectrocoatings are their thermal stability and the fa ct that one can design the surface composition and morphology. (C) 2001 Els evier Science B.V. All rights reserved.