8-methylene-1,4-dioxaspiro[4,5]deca-6,9-diene(MDOSD) is known to polymerize well radically. However the polymerization mode is complicated, due to the concurrent occurrence of different growing radicals; carbon radicals and oxygen radicals. In order to elucidate further the mechanism, the copolymerization with different monomers such as Stryene, MMA, Vinylacetate etc. were carried out and the results were interpreted.
The copolymerization with styrene went cleanly in oxygen radical route (1,9-ring opening type), whereas the copolymerization with vinylacetate went in mixed mode. The copolymerization with α-methylstyrene was also clean 1,9-ring opening. This results indicate that oxy radical is strongly more electrophilic compared with carbon radical and reacts preferentially with styrene monomer. In the present case, steric effect can be another facter, since the carbon radcials are all secondary carbon radical, whereas oxygen radicals are primary radicals. To confirm this mechanism, further work is in progress.
In the extention of study of the effect of aromatic ring formation on the free radical ring-opening polymerization, we prepared another spirotriene monomer, 9-methylene-1.5-dioxaspiro[5.5]undeca-7,10-diene(MDOSUD). The radical polymerization of MDOSUD with AIBN followed the similar behavior to those of MDOSD, and moreover proceeded via the larger portion of 1,2- and 1,4- reaction mode than one. Thus obtained polymer had the following properties. Tg(glass transition temp. detected by DSC), Td(degradation temp. by TGA), and $\eta_{inh}$(inherent viscosity) of the polymer was 0.94℃, 359.64℃ and 0.317, respectively.
Copolymerization with styrene and MMA produced mainly the styrene homopolymer and the MMA homopolymer, because of the poor reactivities of MDOSUD.
