Novel fluorinated hybrid polymer by radical polyaddition of bis(α-trifluoromethyl-β,β-difluorovinyl) terephthalate onto dialkoxydialkylsilanes

To develop the radical polyaddition of bisperfluorisopropenyl esters, the reactions of bis(alpha-trifluromethyl-beta,beta-difluorovinyl) terephthalate [CP2=C(CF3)OCO-C6H4COOC(CF3)=CF2] (BFP) with dialkoxydialkysilane were examined to prepare fluorinated hybrid polymers gearing dialkylsilyl groups in the main chain. Prior to polyaddition, the radical addition reaction of 2-benzoyloxy-pentafluropropene [CF2=C(CF3)OCOC6H5] (BPFP) has been investigated to afford the results that diethoxydimethylsilane (DEOMS) or dimethoxydimethylsilane with BPFP initiated by oxo radical are the best combination for the preparation of polymers. The mechanism of the addition reaction was proposed. Radical polyaddition of BFP with DEOMS initiated by benzoyl peroxide or di-tert-butyl peroxide has yielded polymers of up to molecular weight 1 x 10(6) with rather broad molecular weight distribution. A mechanism for the poly addition reaction is proposed based on the radical addition reaction between BPFP and DEOMS. The step-growth polymerization is initiated by hydrogen abstraction of DEOMS to add a perfluoroisopropenyl group, followed by a 1,7-shift of the radical in the intermediate. The relationship between addition reaction mechanism and polyaddition mechanism was also discussed.