Mussel-inspired modification of carbon fiber via polyethyleneimine/polydopamine co-deposition for the improved interfacial adhesion

A polyethyleneimine/polydopamine (PEI/PDA) hybrid layer was spontaneously co-deposited onto carbon fiber (CF) surface by oxidative co-polymerization through a facile one-step dip-coating approach. The microstructure and chemical characteristics of CF surface before and after modification were investigated and the results manifested that PEI/PDA functionalization could afford abundant amine groups and obviously increase the CF surface energy by 70.5%, which were advantageous to promote the fiber-matrix interfacial interaction and wettability. An enhanced macro-performance was realized by incorporating the functionalized CF (PEI-PDA-CF) into polyurethane (PU) matrix. The prepared PU/PEI-PDA-CF composite exhibited excellent tensile and dynamic mechanical properties. The satisfactory bulk performance was mainly attributed to the superior interfacial adhesion achieved by the hydrogen bonding and π-π* stacking interactions between PEI/PDA coating on CF and PU matrix, which was confirmed by the fracture morphology observations and a 45.7% rise in apparent activation energy value.