Radical Polymerization Behavior of Dimethyl Vinylphosphonate: Homopolymerization and Copolymerization with Trimethoxyvinylsilane Tsuneyuki Sato, Makoto Hasegawa, Makiko Seno, Tomohiro Hirano Department of Chemical Science and Technology, Institute of Technology and Science, Tokushima University, Minamijosanjima 2-1, Tokushima 770-8506, Japan Received 18 April 2007; accepted 30 September 2007 DOI 10.1002/app.28626 Published online 6 June 2008 in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: Dialkyl vinylphosphonates such as di- methyl vinylphosphonate (DMVP) and diethyl vinyl- phosphonate were quantitatively polymerized with dicumyl peroxide (DCPO) at 1308C in bulk. The polymer- ization of DMVP with DCPO was kinetically studied in bulk by fourier transform near-infrared spectroscopy (FTNIR) and electron spin resonance (ESR) spectroscopy. The initial polymerization rate (R p ) was given by R p 5 k[DCPO] 0.5 [DMVP] 1.0 at 1108C, being the same as that of the conventional radical polymerization involving bimolec- ular termination. The overall activation energy of the poly- merization was estimated to be 26.2 kcal/mol. The poly- merization system involved ESR-observable propagating polymer radicals under the practical polymerization condi- tions. ESR-determined rate constants of propagation (k p ) and termination (k t ) were k p 5 19 L/mol s and k t 5 5.8 3 10 3 L/mol s at 1108C, respectively. The molecular weight of the resultant poly(DMVP)s was low (M n 5 3.4 2 3.5 3 10 3 ), because of the high chain transfer constant (C m 5 3.9 3 10 22 at 1108C) to the monomer. DMVP (M 1 ) showed a considerably high reactivity in the radical copolymeriza- tion with trimethoxyvinylsilane (TMVS) (M 2 ) at 1108C in bulk, giving an inorganic component-containing functional copolymer with potential flame-retardant properties; r 1 5 1.6 and r 2 5 0. Ó 2008 Wiley Periodicals, Inc. J Appl Polym Sci 109: 3746–3752, 2008 Key words: radical polymerization; kinetics; ESR; copoly- merization; dialkyl vinylphosphonate; trimethoxyvinylsi- lane INTRODUCTION Considerable attention has been paid to phosphorus- containing polymers because of their flame-retarding effects, excellent adhesion to metals, metal ion bind- ing characteristics, and so on. 1–7 Radical homo- and copolymerizations of various P-vinyl monomers have been studied by some workers from the stand- points of not only the synthesis of phosphorus-con- taining polymers but also the substituent effects of the phosphorus on the vinyl polymerization. 8–15 Dia- lkyl vinylphosphonates show a relatively high poly- merizability but give only oligomers in the radical homopolymerization, whereas their anionic polymer- izations afford high molecular weighted poly- mers. 10,11,13 In the radical copolymerization they can be well copolymerized with vinyl acetate, as noncon- jugative monomer, but not with conjugative mono- mers such as styrene, acrylonitrile, and methyl meth- acrylate. 8,10–12,14 Thus, dialkyl vinylphosphonates have been established to be an electron-accepting nonconjugative monomer in the radical copolymer- ization. However, radical polymerization kinetics of dialkyl vinylphosphonates has not been reported. Here we have studied kinetically the radical homo- polymerizations of dimethyl vinylphosphonate (DMVP) and diethyl vinylphosphonate (DEVP), and also the copolymerization of DMVP with trimethoxy- vinylsilane (TMVS) as a nonconjugative monomer giving an inorganic component-containing functional copolymer with potential flame-retardant properties. 7 Dicumyl peroxide (DCPO) was used as an initiator. This article describes the kinetic behaviors of DMVP and DEVP in the polymerization with DCPO and the results of the copolymerization of DMVP and TMVS. EXPERIMETAL Materials DMVP (98%) (Lancaster, UK) and DEVP (97%) (Aldrich, USA) were used as received. TMVS and dioxane were used as solvent after distillations. DCPO was recrystallized from methanol, containing a small amount of water. Polymerization Homo- and copolymerizations of dialkyl vinyl- phosphonates were carried out in a degassed sealed Correspondence to: T. Hirano (hirano@chem.tokushima-u. ac.jp). Journal of Applied Polymer Science, Vol. 109, 3746–3752 (2008) V V C 2008 Wiley Periodicals, Inc.