The solution cyclocopolymerization of 1

3 divinyl 1

1

3

3-tetramethyldisiloxane(DVDS) with styrene(St) at 130℃ was investigated.The overall conversions for all copolymerization runs were controlled less than 10%.The copolymer compositions and percentages of DVDS forming the ring structures in the copolymers were determined by1H and 29Si NMR

respectively.Using the nonlinear parameter estimation

the cyclization coefficients and reactivity ratios were calculated as r1=0. 102

r2=34.8

rc=0.0210

Kc=3.81mol/L

and K'c=0.389mol/L.The 95% reliability intervals for the estimated kinetic constants were given also.The experimental results indicate that DVDS was less active than St

and the DVDS uncyclized radicals were easy to form the cyclic structures via the intramolecular cyclization. Due to the steric hindrance

the activities of DVDS cyclized radicals were lower than its uncyclized ones.