Poly(trimethylene terephthalate)/silica nanocomposites prepared by dual in situ polymerization: synthesis, morphology, crystallization behavior and mechanical properties

Abstract

AbstractThe sol–gel technique has provided promising opportunities for the preparation of polymer/inorganic hybrid materials at the molecular level, which ensures the inorganic particles are well dispersed in the organic matrix. In this work, poly(trimethylene terephthalate) (PTT)/silica nanocomposites were fabricated via the sol–gel technique and in situ polymerization. Fourier transform infrared and nuclear magnetic resonance analyses confirmed that some PTT molecular chains were grafted to the surface of silica. Unlike pure PTT, the grafted PTT was insoluble in a mixed solvent of chloroform and hexafluoro‐2‐propanol. Both transmission electron microscopy and scanning electron microscopy showed that the silica particles, with a size of 40–50 nm, were homogeneously dispersed in the PTT matrix with no preferential accumulation in any region. Differential scanning calorimetry revealed that the glass transition temperature and cold‐crystallization peak of the composites gradually increased with increasing silica loading. A simultaneous increase of stiffness and toughness was observed for the nanocomposites. Moreover, polarized optical microscopy showed that the nanocomposites exhibited interesting banded spherulites, which were different from banded spherulites of PTT previously reported. The nanocomposites with covalent bonding between silica and PTT gave a series of interesting results, such as elevated glass transition temperature, simultaneous increase of stiffness and toughness as well as surprising banded spherulites. Copyright © 2009 Society of Chemical Industry