Free-radical polymerization of styrene and divinylbenzene: comparison between the conventional fre radical process and the controlled free radical process mediated by nitroxide

• Grant number: 12/12184-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2012
• End date: July 31, 2013
• Field of knowledge: Engineering - Chemical Engineering - Industrial Operations and Equipment for Chemical Engineering
• Principal Investigator: Reinaldo Giudici
• Grantee: Rodolfo Di Nápoli Nogueira
• Host Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The copolymerization of styrene with divinylbenzene allows one to obtain branched /crosslinked polymers. The process takes place according to the classic mechanism involving free radicals generated by decomposition of chemical initiators (or by the decomposition of the styrene monomer, if under high temperatures). More recently (last two decades), new compounds that are able to work as controllers or mediators of the free radical polymerization process were discovered, the nitroxides being an important class of such controllers. The mediators/controllers reversibly convert the polymeric growing radicals into dormant species, thus increasing the lifetime of the radicals and allowing the control of the growth of the polymer chains. As a result, better control of the growth of the polymer chains is possible by generating chains with more uniform sizes with distinct properties. In the present research project, the conventional free radical polymerization process and the nitroxide-mediated free radical polymerization process will be studied and compared. The product will be characterized by gravimetry (monomer conversion), extraction (gel fraction), and near-infrared spectroscopy (concentration of pendant double bonds).(AU)