Catecholamine polymers as surface modifiers for enhancing interfacial strength of fiber-reinforced composites

Abstract

Mussel-inspired catecholamine polymers (poly(dopamine) and poly(norepinephrine)) were coated on the surface of carbon and glass fibers in order to increase the interfacial shear strength between fibers and polymer matrix , and consequently the interlaminar shear strength of fiber-reinforced composites. By utilizing adhesive characteristic of the catecholamine polymer, fiber-reinforced composites can become mechanically stronger than conventional composites. Since the catecholamine polymer is easily constructed on the surface by the simultaneous polymerization of its monomer under a weak basic circumstance, it can be readily coated on micro-fibers by a simple dipping process without any complex chemical treatments. Also, catecholamines can increase the surface free energy of micro-fibers and therefore, can give better wettability to epoxy resin. Therefore, catecholamine polymers can be used as versatile and effective surface modifiers for both carbon and glass fibers. Here, catecholamine-coated carbon and glass fibers exhibited higher interfacial shear strength (37% and 27% increases, respectively) and their plain woven composites showed improved interlaminar shear strength (13% and 9% increases, respectively) compared to non-coated fibers and composites.