Brush-like poly(ethylene glycol) grafting on SiO2 nanoparticles with in-situ polymerization

This work presents the grafting of poly(ethylene glycol) (PEG) on the SiO2 nanoparticles by the use of the azo-groups bonded SiO2 as a radical initiator and poly(ethylene glycol) methyl ether methacrylate (PEGMA) as a macromonomer, respectively. Then a kind of organic-inorganic composite particles with brush-like PEG fixed covalently on the SiO2 nanoparticles, SiO2-PEG, is synthesized. The successful synthesis of SiO2-PEG is confirmed by FT-IR, XPS, and TEM techniques. Results show that the conversion degree of PEGMA can reach nearly 30% while the PEG graft amount accounts for ca. 43% of the total weight of the composite particles. After the PEG is grafted on the SiO2 nanoparticles, the mobility of PEG chains is hindered by the proximity of oxide phase of SiO2. As a result, PEG phase is strongly disturbed. Consequently, the grafted PEG melts at a low temperature with small quantity of heat enthalpy. Copyright (c) 2014 John Wiley & Sons, Ltd.