Preparation Of Poly-D,L-Lactide Based Nanocomposites With Polymer-Grafted Silica By Melt Blending: Study Of Molecular, Morphological, And Mechanical Properties

Polylactide was first designed for the pharmaceutical and medical fields. Unfortunately, polylactide, especially poly-d,l-lactide (PDLLA), presents too low mechanical properties for a wide range of applications. The addition of silica nanoparticles should reinforce the mechanical strength of PDLLA. In order to improve silica/polymer interactions, this study focused on the preparation of polymer chain grafted silica using two grafting methods. The first strategy relied upon the ring opening polymerization of d,l-lactide on initiating silica surface (ie, "grafting from"). The second approach considered a sol-gel synthesis process in presence of Si-OR terminated polylactide chains to promote grafting of these chains on new silica particles (ie, "grafting to" method). Only "grafting from" silica successfully led to a nanoscale dispersion into the polyester matrix for silica content up to 5 wt%. A 3 wt% content of this silica allowed improving Young modulus of 106.0% and ultimate tensile stress of 63.7% compared to the PDLLA control.