Authors: T.A. Shefelbine, R.E. Marx, J.M. Nelson, J.W. Longabach, M.L. Brostrom and M.I. Bucket
Affilation: 3M Corporate Research, United States
Pages: 75 - 78
Keywords: clay nanocomposites, block copolymers, exfoliation
This presentation will focus on the use of Controlled Architecture Materials (CAMs): block copolymers, telechelic, gradient and star branched polymers as additives to induce the exfoliation of nanoclays in thermoplastic resins. Conventional exfoliation methods include polymerizing a monomer around a pre-dispersed clay, dissolving a polymer and a clay in a mutually inclusive solvent, or using additives to aid in the exfoliation during melt compounding. Traditional melt additives include random or graft copolymers, such as maleic anhydride grafted polyolefins, and are mainly utilized with organically modified clays. The main drawback in utilizing these random copolymers in nanocomposites is their inefficient mediation of the exfoliation process, which demands that a fairly high level of additive be used to exfoliate the clay. Block copolymers, on the other hand, have been shown to be much more efficient and can be further designed to augment other physical properties such as impact resistance and elongation. Furthermore, block copolymers can be tuned to the polymeric resin and the different clays, organically modified or not. The CAM-mediated approach to exfoliation offers the ability to tune the block copolymer reactivity based on clay hydrophobicity or pillaring agent composition.