Incorporating titanium dioxide (TiO₂) nanoparticles into the polymeric matrix offers an opportunity to obtain nanocomposites with improved functionality. In this study, the commercial TiO₂ nanoparticles (TNP) were surface treated by different concentrations of aminopropyl triethoxy silane (APTS) as a coupling agent and triethylamine (Et₃N) as a surface grafting catalyst by an aqueous process to prepare a nanocomposite with superior properties. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) were performed to confirm the successful surface modification of TNP. The prepared modified TiO₂ nanoparticles (mTNP) with different weight fractions were used as initiator for in-situ grafting ring-opening polymerization of poly(l-lactide)-b-poly(\(\varepsilon \)-caprolactone) P(LLA-b-CL). It was found that the mTNP content and the concentration of the coupling agents have essential roles in the molecular characteristics and thermal and mechanical properties of the nanocomposite. The results indicated that the samples having mTNP with a high concentration of APTS had higher molecular weight and superior thermal and mechanical properties. In addition, the prepared samples showed remarkably improved thermal and mechanical properties compared to a neat polylactide (PLLA). The described in-situ synthetic methodology allows an optimal reaction between the components of the synthesis system for the preparation of nanocomposites with improved thermal and mechanical properties.

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