In situ prepared poly(DL-lactic acid)/silica nanocomposites: Study of molecular composition, thermal stability, glass transition and molecular dynamics

Abstract The objective of the present study was to prepare a series of poly(DL-lactic acid) (PDLLA) nanocomposites with four different amounts of silica (SiO 2 ) nanoparticles (2.5, 5, 10 and 20 wt%), following a new two-step synthesis route: ring opening polymerization of DL-lactide and polycondensation. Effects of different percentage of SiO 2 on various properties such as molecular weight, crystallinity, thermal stability, glass transition temperature ( T g ) and molecular dynamics, are discussed and compared with the theoretical models available in literature. Thermal stability of PDLLA was substantially enhanced from the addition of SiO 2 , while calorimetry and dielectric spectroscopy showed increased T g in the nanocomposites, as well as indications for formation of interfacial rigid amorphous polymer fraction.