Simultaneous Hardening/Ductilizing Effects of Cryogenic Nanohybridization of Biopolyamides with Montmorillonites

We prepared organic/inorganic bionanohybrid resins of polyamides containing pyrrolidone in the backbone derived from the salt monomers of an itaconic acid biomolecule with various nanofillers, montmorillonites (MMTs), by cryogenic nanohybridizations. The nanohybridizations with MMTs hardened and strengthened the polypyrrolidone bioplastic resins owing to a simple reinforcement of hard filler incorporation. On the other hand, the elongation at break of the resins is unexpectedly increased by the nanohybridization with MMT sodium salt (NaMMT) to enhance the strain energy density, which differed from those of the nanohybrids with other organically modified MMTs. From spectroscopic analyses, we discuss the mechanism of such ductilization effects by NaMMT, the catalytic effect of NaMMT on partially opening the pyrrolidone ring to make polymer backbones flexible and to form carboxyl side chains that are strongly interactive with NaMMT fillers.