Design of Compatibilizing Interfacial Polymer Layers Using a Macroinitiator M. K. Oduola Department of Chemical Engineering, University of Port Harcourt, Port Harcourt, Nigeria koye_oduola@yahoo.com Key words: Immobilization, surface-attached radicals, graft polymerization. Abstract. Immobilization of an amine-containing peroxide macroinitiator APM onto solid mineral surfaces has been achieved via physical/chemical adsorption of its macromolecules from solution. A systematic variation of reaction parameters upon graft polymerization initiated by surface- attached APM including nature of monomer and solvent has been conducted. The effect of solvent and nature of monomer on the overall constant of polymerization, effective activation energy, initiation efficiency as well as other parameters of elementary stages of the process has been established. It has been revealed that the involvement of TiO 2 particles with the surface-attached radicals in the heterogeneous polymerization process profoundly influenced all the elementary stages, particularly chain transfer and termination. ITRODUCTIO Peroxide modification of the surface of disperse fillers and pigments is carried out with the objective to enabling their participation in the elementary reactions of polymerization: initiation, chain propagation and termination. As a result, a compatibilizing interfacial polymer layer is formed with macromolecules grafted to the surface [1-6]. However, localization of the initiation sites on the surface affects not only the polymerization kinetics, but also determines to a remarkable extent the chemical composition, structure and the physical properties of the resulting polymers. This in turn determines the overall properties of the heterogeneous polymer system. A number of works has been focused on the amount of polymer grafted onto the surface [2,3,5], whereas little or no data is available on the initiation kinetics and the effect of immobilization on the propagation and termination of the growing polymer chains. To gain control over the polymerization process initiated from the surface-attached initiator however one of the prerequisites is a well-established initiating layer. Application of unconventional free radical polymerization initiators has been encouraged in recent years owing to their capabilities to eliminate the limitations encountered with the use of traditional ones. These include unmanageable rate of polymerization (in particular, when block polymers are needed), and limited molecular weight of the resulting polymers [3-5]. As an example, it has been shown that the presence in the initiator structure of a second radical generating functionality causes its entrance into the growing macrochains to form macromolecules, which consequently become active participants of chain re-initiation, propagation, transfer and termination reactions [7,8]. The presence in the initiator molecules of additional functional groups however leads to sufficiently complex polymerization kinetics. This is aggravated by the fact that polymer peroxides have been little investigated with regards to their initiating characteristics upon free radical polymerization of vinyl monomers as compared to conventional organic peroxides. In this paper the idea of activating the solid surface by adsorption of polymers with peroxide moieties is further developed. The radical polymerization process initiated by a peroxide-active pigment, titanium dioxide modified by an amine-containing peroxide macroinitiator TiO 2 -mod-APM, has been investigated for two model vinyl monomers: styrene St and methyl methacrylate MMA, differentiated by polarity and chain termination mechanism. This will not only facilitate the elucidation of the problem described above, but also go a long way to throw more lights in the general mechanism of vinyl polymerization involving polyreactive macroinitiators. Advanced Materials Research Vols 62-64 (2009) pp 311-316 Online: 2009-02-20 © (2009) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.62-64.311 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, www.ttp.net. (ID: 41.220.69.205, University of Port Harcourt, Niger-22/05/15,00:34:18)