Hybrid Nanocomposites of TPU ‐ PDMS Blend Based on Halloysite Nanotubes and Nanohydroxyapatite

This work reports a hybrid filler based on halloysite nanotubes (HNT) and nanohydroxyapatite (Hap), synthesized by in‐situ co‐precipitation of Hap on HNT templates and incorporated into a compatibilized thermoplastic polyurethane (TPU)–polydimethylsiloxane (PDMS) blend at a 70:30 ratio. The resulting mixture of Hap‐coated HNTs and discrete Hap nanoparticles was successfully dispersed in the TPU–PDMS matrix by solution mixing at loadings up to 3 phr. X‐ray diffraction verified the Hap phase in the hybrid filler mixture and showed no significant change in crystallite size relative to pristine Hap, while DSC indicated that hybrid filler addition improved the crystallization of the TPU soft segments and the cold‐crystallization enthalpy of PDMS, consistent with filler‐induced ordering in both phases. Dynamic mechanical analysis further revealed that the storage modulus of the nanocomposites increased progressively with hybrid filler loading and, at 3 phr HNT–Hap, became comparable to that of pristine TPU. Overall, nanocomposites containing the hybrid HNT–Hap exhibited markedly higher tensile strength than those filled with only Hap or only HNT; the 3 phr hybrid filler formulation achieved a 120% increase in tensile strength compared to the neat TPU–PDMS blend. Moreover, the incorporation of HNT‐Hap promotes the thermal stability of nanocomposites considerably.