Reactivity in radical and anionic copolymerizations of 4-(trimethylsilyl)styrene. Synthesis of soluble poly{(1,4-divinylbenzene)-co-[4-(trimethylsilyl)styrene]}

Radical copolymerization of 4-(trimethylsilyl)styrene (TMSS) with styrene were carried out to estimate the reactivity of TMSS. The monomer reactivity ratios r₁ and r₂ in the radical copolymerization of TMSS (M1) with styrene (M2) were evaluated as 0,28 and 0,48, respectively. The value r₁ · r₂ (= 0,13) being smaller than unity indicates that the trimethylsilyl group at para position behaves as an electron-withdrawing substituent. Reactions of lithium diethylamide with TMSS in the presence of diethylamine, gave the 1:1 addition product 1-[2-(N,N-diethylamino)-ethyl]-4-(trimethylsilyl)benzene. Kinetic analysis showed that the second-order rate constant (k) for this addition reaction is 34,4 · 10^?4 dm³ · mol^?1 · s^?1, which is by a factor of 2 larger than that for the reaction with styrene (k = 16,0 · 10^?4 dm³ · mol^?1 · s^?1). The fact is also compatible with the above consideration for the r₁ · r₂ values. Lithium diisopropylamide initiated anionic copolymerizations of TMSS with 1,4-divinylbenzene (DVB) were also examined. The polymerizations proceed smoothly without any gel formation and the resulting copolymers are soluble in various common solvents such as benszene, tetrahydrofuran, chloroform, etc. Thus, novel organosilicon-containing polymers having appropriate amounts of reactive pendent vinyl groups are easily synthesized.