Poly(butylene adipate-co-terephthalate)
(PBAT)
is a thermoplastic biodegradable polyester with broad market prospects
due to its desirable toughness, ductility, and water resistance. However,
compared with traditional plastics, its insufficient mechanical strength
limited its scope of applications. Herein, inspired by the reinforcement
concept of polyurethane and leveraging the rich presence of aromatic
rings in the PBAT molecular chain, we incorporated cation–π
and hydrogen-bonding interactions into PBAT chains to enhance the
mechanical properties. Cationic quaternary ammonium (QA) groups were
coupled into the mainchain generating PBATQA copolyester through an
isocyanate chain extension reaction, and the effects of QA content
on crystallinity, mechanical properties, and melt rheology were investigated.
The synergistic occurrence of hydrogen-bonding and cation–π
interactions was demonstrated by DFT calculation. At a low QA content
of 1.7 wt %, we achieved a significantly enhanced tensile strength
of 44.2 MPa and an elongation at break of 1498%. In addition, due
to the broad melting range and the relatively high modulus around
melting transition temperature, the synthesized PBATQA can be easily
processed into complicated objects via 3D printing and implementation
of complex shape memory processes.