No abstract

Bulk copolymerization of vinylidene fluoride (or 1,1-difluoroethylene (VDF)) with 4,5,5-trifluoro-4-ene pentyl acetate (FAc) initiated by di-tert-butyl peroxide is presented. A series of nine copolymerization reactions was investigated from initial [VDF] 0/[FAc]0 molar ratios ranging from 32/68 to 95/5. Both these comonomers copolymerized in this range of copolymerization. Moreover, these comonomers homopolymerized separately in these conditions. The copolymer compositions of these randomtype copolymers were calculated by means of 1 H and 19 F NMR spectroscopies and allowed one to quantify the respective amount of each monomeric unit in the copolymer. From the Tidwell and Mortimer method, the reactivity ratios, ri, of both comonomers were determined showing a higher incorporation of FAc in the copolymer (rFAc ) 3.26 ( 1.49 and rVDF ) 0.17 ( 0.10 at 120°C). Alfrey-Price's Q and e values of trifluorovinyl acetoxy monomer FAc were calculated to be 0.060 (from QVDF ) 0.008) or 0.040 (from QVDF ) 0.015) and +1.14 (vs eVDF ) 0.40) or +1.23 (vs eVDF ) 0.50), respectively, indicating that FAc is an electron-accepting monomer. The normalized monomer-diad and -triad fractions as a function of the polymer composition were obtained from the comonomer sequence distribution theory and this was evidenced by 19 F NMR analysis.

The kinetics of free radical telomerization was studied. The theoretical relations that can be applied in reactions of this type, were evaluated. When transfer predominates, the equations giving the variations of monomer, telogen and initiator as a function of time were established. Moreover, instantaneous and cumulated number and weight average degrees of polymerization were calculated. The resulting relations were checked on the example of the telomerization of 2,3-epoxypropyl methacrylate with bromotrichloromethane in the presence of two initiators and two different temperatures. Comparison of the experimental results with the theoretical ones revealed the scope of application of the general formulae giving the average degrees of polymerization.La ttlomtrisation radicalaire d'un monomere M avec un ttlogkne XY amorcte par I, s'tcrit gtneralement de la faGon suivante: Amorcage: Propagation: Transfert: Terminaison: kd ko 12 -