Covalent Grafting of Hydroxylated MWCNTs in TPU via In Situ Polymerization for Antistatic Applications With an Ultralow Percolation Threshold

Thermoplastic polyurethane (TPU) nanocomposites reinforced with hydroxylated multi-walled carbon nanotubes (MWCNTs) were synthesized via in situ polymerization of polycarbonate diol (PCDL), isophorone diisocyanate (IPDI), and chain extender. The MWCNTs were covalently integrated into the TPU matrix through reactions between surface hydroxyl groups and isocyanate. Systematic characterization revealed uniform MWCNT dispersion (SEM/XRD) without agglomeration up to 4 wt% loading. The nanocomposites exhibited enhanced hardness (80 to 89 Shore A), elevated thermal stability (5% weight loss temperature increased by 6 °C), and restricted soft-segment chain mobility (glass transition temperature rose from −37.34 to −26.26 °C). Critically, surface resistivity decreased dramatically from 10 14 (pure TPU) to 3 × 10⁶ Ω (4 wt% MWCNTs), achieving antistatic performance (5 × 10 11 Ω) at only 1 wt% loading. This work demonstrates a robust strategy for developing high-performance antistatic TPU nanocomposites.