A Study on the Properties of Poly (Styrene-co-Methyl Methacrylate)/Silica Aerogel Nanocomposites Prepared via in situ SRNI ATRP

摘要

Simultaneous reverse and normal initiation technique for atom transfer radical copolymerization (SRNI ATRP) of styrene and methyl methacrylate in the presence of hexamethyldisilazane (HMDS)-modified silica aerogel nanoparticles (H-SAN) and investigating the effect of addition of H-SAN on the copolymerization and thermal properties of the products are discussed. Some unique features of the H-SAN are evaluated using nitrogen adsorption/desorption isotherm, SEM and TEM. Conversion and molecular weight determinations were carried out using GC and SEC respectively. Adding of H-SAN by 3 wt results in decrement of conversion from 94 to 73. In addition, molecular weight of copolymer chains decreases from 19500 to 16000 g.mol(-1) . However, polydispersity index values increases from 1.29 to 1.65. Linear increase of ln(M-0/M) with time for all the samples shows that copolymerization proceeds in a living manner. Increasing thermal stability of the nanocomposites is demonstrated by TGA. DSC results show a decrease in glass transition tem- perature from 70.3 to 63.5 degrees C by addition of 3 wt H-SAN.