Tough and strong nacre-like composites from hyperbranched poly(amido amine) and clay nanosheets cross-linked by genipin

Tough and strong nacre-like composite films were fabricated from hyperbranched poly(amido amine) (HPAMAM) and clay nanosheets with the aid of genipin crosslinking. SEM observation and SAXS analysis indicated the genipin crosslinked HPAMAM/nanoclay composite films had a compact structure. However, DMA results showed that HPAMAM molecules still had excellent flexibility. FTIR analysis suggested that the HPAMAM molecules maintained their strong ability to form hydrogen bonds after crosslinking. Therefore, characteristics of sacrificial bonds were found. In addition, dual networks were thought to have been established inside the composite films, that is, a primary chemical network and a secondary physical network. Consequently, the genipin crosslinked HPAMAM/nanoclay composite films were shown to be tough and strong. The fracture toughness was as high as 5.03 MJ m(-3) and the mechanical strength was about 152.9 MPa. Lastly, the good biocompatibility of all the components, including HPAMAM, nanoclay and genipin, give great opportunities for these composites to be widely applied in biomedical research.