Block copolymer epoxidation: influence of the epoxidating agent in the control of epoxidation

GARATE, H.; FASCIO, M.; MONDRAGÓN, I.; GOYANES, S.; D' ACCORSO, N.

Lyon

Congreso; Frontiers in polymer Science, Second International Symposium; 2011

Our objective is to develop nanostructured epoxy composites by the incorporation of block copolymers. Block copolymers (BC) have attracted special attention because of their ability to self-assemble into different nanoscale structures. This ability can be used to design novel polymeric material with potentially interesting properties. Furthermore, block copolymers blended with epoxy resins maintain the ability of these copolymers to generate new nanostructures, when one of the BC block is miscible with the epoxy resin. A very important issue to develop these materials is the compatibilization between the epoxy and the block copolymer. In this regard, chemical modification of BC containing a polydiene block can be carried out by the epoxidation reaction on the double bonds. This pathway can lead to an improvement in mechanical properties and in the stability of nanostructured materials. [1-2] It is known that the epoxidation degree is a critical parameter to obtain nanostructured materials.[1] Then the development of a method to obtain epoxidized BC in a controlled way becomes necessary. In this work we make a comparative study of the epoxidation of a linear poly(styrene-b-isoprene-b-styrene) using two epoxidation agents: a typical oxidating agent (hydrogen peroxide) and oxone [3]. From the characterization of the products we have determined the optimal conditions for both epoxidations. We performed the spectroscopic characterization using nuclear magnetic resonance and infrared spectroscopy. Molecular weight distributions and polydispersity of the products have been analysed by gel permeation chromatography. Further characterization has been performed by termogravimetric analysis and differential scanning calorimetry The epoxidation with oxone results more efficient since it conducts to a product with a more controlled molecular weight distribution than in the case of using hydrogen peroxide.