Polyphenolic nanodots loaded multi-layer MXene for strong, tough and rapidly biodegradable polyvinyl alcohol/starch...

Inspired by spider silk, polyphenolic nanodots (PTa) loaded multi-layer MXene (mMXene-PTa) through hydrogen and coordination bonds was prepared by self-polymerizing tannic acid on mMXene and used as a new crosslinker for polyvinyl alcohol (PVA). Together with starch (ST), mMXene-PTa was compounded with PVA and exfoliated to fabricate PVA/ST/mMXene-PTa nanocomposite. The phenolic hydroxyl groups in PTa formed high-density H-bonds with PVA and ST, creating an organic-inorganic dynamic crosslinking network with mMXene-PTa as nodes. PVA/ST/mMXene-PTa achieved dual effects of reinforcement and toughening owing to the dynamic deformation and reconstruction of this crosslinking network following cyclical breaking and reforming of H-bonds under external loads. For instance, 5 % mMXene-PTa simultaneously increased the tensile strength of PVA/ST blend by 75 % and toughness by 108 %. Even at a 40 % reduced dosage, mMXene-PTa demonstrated comparable enhancements to mMXene in improving PVA/ST blend's strength and toughness. Meanwhile, uniform loading of PTa on mMXene enhanced its migration resistance and thermal stability. This amplified the UV-absorbing and radical scavenging capabilities of PTa, thereby endowing PVA/ST/mMXene-PTa with significantly improved resistance to photo, thermal and oxidative degradation. Furthermore, PVA/ST/mMXene-PTa showed self-healing ability and remarkably increased biodegradation rate. Taken together, this work explores a possible paradigm for the design of advanced PVA/ST materials.