Aqueous-Based Functionalizations of Titanate Nanotubes: A Straightforward Route to High-Performance Epoxy Composites with Interfacially Bonded Nanofillers

Nanotube surface treatment is crucial in preparation of high-quality nanomaterials for advanced applications. Herein, we provide an environmentally friendly and practical route to the design of high performance composites using the surface chemistry of titanate nanotubes (TiNT) to enhance the interfacial nanotube–epoxy bonding. Insights presented here improve understanding of how different organic layers (a low-molecular-weight bisphosphonate (APMBP), branched polyethylenimine (PEI), or polydopamine (PDA)) coated on TiNT surface and bearing active hydrogen functionalities (NH, OH) affect epoxy–amine cross-link reaction and network buildup and consequently morphology and thermomechanical properties of the final epoxy–TiNT composites. The kinetics of cross-linking was experimentally studied and successfully fitted by a mechanistic kinetic model, which considered the effects of NH and OH functionalities. We found that APMBP was not involved in the epoxy–amine cross-link reaction entering only into physical i...