Initiator-Fragment Incorporation Radical Polymerization of Diallyl Phthalate: Kinetics, Formation of Hyperbranched Polymer, and Iridescent Porous Film Thereof Tsuneyuki Sato, Kazuki Nomura, Tomohiro Hirano, Makiko Seno Department of Chemical Science and Technology, Faculty of Engineering, Tokushima University, Tokushima 770-8506, Japan Received 17 November 2005; accepted 29 December 2005 DOI 10.1002/app.24036 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: Diallyl phthalate (DAP) was polymerized in toluene using dimethyl 2,2'-azobisisobutyrate (MAIB) of high concentrations (0.1– 0.9 mol/L) as initiator. The poly- merization of DAP of 1.50 mol/L with MAIB of 0.50 mol/L proceeded homogeneously at 80°C without gelation to give soluble polymers in a high yield of 93%. Kinetic results of the homogeneous polymerization at 80°C suggest significant contributions of the degradative chain transfer and the pri- mary radical termination as shown by the rate equation, R p = k [MAIB] 0.8 [DAP] 1.0 (R p = polymerization rate). The poly- mer formed in the polymerization of DAP (1.30 mol/L) with MAIB (0.50 mol/L) at 80°C for 8 h consisted of the DAP units with (17 mol %) and without (47 mol %) double bond and the methoxycarbonylpropyl group (36 mol %) as MAIB- fragment. The large fraction of the incorporated initiator- fragment as terminal group indicates that the polymer has a hyperbranched structure. The film cast from a solution of the hyperbranched poly(DAP) in tetrahydrofuran showed an iridescent color. The confocal scanning laser microscope im- age of the film revealed that the iridescent film contained the pores of about 1 m arranged in an ordered array. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 408 – 415, 2006 Key words: radical polymerization; kinetics; hyper- branched; divinyl monomer; crosslink; viscosity INTRODUCTION Diallyl and multiallyl monomers such as diallyl phthalate (DAP) and diallyl diglycol carbonate (DADGC) have found various industrial applications in the production of a range of thermoset products, moldings and coatings for connectors and insulators, plastic lenses, safety shields, and so on. 1 On the other hand, we have developed the initiator- fragment incorporation radical polymerization (IFIRP) as a novel versatile approach for one-pot synthesis of soluble hyperbranched polymers, where high initiator concentrations are used in the radical homopolymer- ization or copolymerization of a divinyl monomer. 2–7 In general, the radical polymerization system contain- ing a di(multi)vinyl monomer gives an insoluble crosslinked polymer, of which the molecular weight is treated to be extremely high or infinite. However, the use of much higher initiator concentration in the po- lymerization of di(multi)vinyl monomer results in so great a decrease in the molecular weight that the re- sulting polymer ultimately becomes soluble. The sol- uble polymer is no longer linear, but is hyper- branched. A large number of initiator-fragments are incorporated as terminal groups in the polymer via initiation and primary radical termination. Here we have attempted to extend the IFIRP to DAP as an diallyl monomer, where the polymerization be- havior of DAP with dimethyl 2,2'-azobisisobutyrate (MAIB) was kinetically investigated. The resulting sol- uble poly(DAP)s were characterized. Interestingly, the cast film from the polymer solution in tetrahydrofuran (THF) was further found to become an iridescent po- rous film. The present article describes the kinetic results of the IFIRP of DAP, characterization of the resulting polymer, and formation of iridescent porous film thereof. EXPERIMENTAL Materials Commercially available diallyl phthalate (DAP) was used after distillation. Dimethyl 2,2'-azobisisobutyrate (MAIB) was recrystallized from methanol. Toluene was treated with sulfuric acid and distilled. Other solvents were used after distillation. Polymerization Polymerizations were carried out in a degassed and sealed glass tube at a given temperature. The resulting Correspondence to: T. Sato (sato@chem.tokushima-u.ac.jp). Journal of Applied Polymer Science, Vol. 102, 408 – 415 (2006) © 2006 Wiley Periodicals, Inc.