ATRP of Methyl Methacrylate in the Presence of HMDS-Modified Silica Aerogel: ARGET Approach

Abstract

Activators regenerated by electron transfer for atom transfer radical polymerization of methyl methacrylate without and in the presence of hexamethyldisilazane-modified silica aerogel were investigated. Some inherent features of the modified silica aerogel are evaluated by using nitrogen adsorption/desorption isotherm, scanning and transmission electron microscopy. Conversion of the monomer and also molecular weight of the samples were determined using gas and size exclusion chromatography respectively. According to the results, addition of the modified silica aerogel (3 wt%) leads to decrement of conversion (from 82 to 67%) and molecular weight (from 17,183 to 15,062 g mol− 1). Meanwhile, polydispersity index value increases from 1.09 to 1.44. Linear increase of ln(M0/M) with time for all the samples shows that polymerization proceeds in a living manner. Thermal gravimetric analysis results indicate that by increasing modified silica aerogel content, slight improvements in thermal stability of the composites were obtained. Differential scanning calorimetry results show a decrease in Tg from 89.2 to 82.7 °C by addition of modified silica aerogel (3 wt%). Kinetics and thermal results indicate that surface chemistry of the silica aerogel can not present considerable effects on the properties of the prepared composites.