Telechelic Diiodopoly(VDF-co-PMVE) Copolymers by Iodine Transfer Copolymerization of Vinylidene Fluoride (VDF) with Perfluoromethyl Vinyl Ether (PMVE)

• Published in: Macromolecules 2010-04, Vol.43 (8), p.3652-3663
• Main Authors: Boyer, Cyrille, Ameduri, Bruno, Hung, Ming H
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical Sciences; Copolymerization; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Polymers; Preparation, kinetics, thermodynamics, mechanism and catalysts
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma100207h

The synthesis and the characterization of fluoroelastomers, based on vinylidene fluoride (VDF) and perfluoromethyl vinyl ether (PMVE), poly(VDF-co-PMVE) copolymers, by iodine transfer copolymerization are presented. These statistic poly(VDF-co-PMVE) copolymers were prepared in the presence of a perfluoromonoiodo functional chain transfer agent (CTA), C6F13I, or telechelic diiodoperfluoroalkane CTAs, IC6F12I and IC4F8I, using an emulsion process without any surfactant. Quasi-optimal conditions were found to lead to poly(VDF-co-PMVE) copolymers in satisfactory yields. The copolymer compositions, the molecular weights, and end-groups of these random-type copolymers were assessed by means of 19F NMR spectroscopy. Model molecules containing only one PMVE unit were synthesized by the radical addition of different CTAs (ICl, ICF2I, CF3I) onto PMVE to help in the assignments by 19F NMR spectroscopy of the characteristic signals of the end-group, i.e., −CF2CF(OCF3)I and −CF(OCF3)CF2I. Indeed, only −CH2CF2−I (major amount) and −CF2CH2−I end-groups of these poly(VDF-co-PMVE) copolymers were noted, showing the high reactivity of PMVE−I in the iodine transfer polymerization of VDF. The CTA concentration enabled one to control the molecular weights of the resulting telechelic diiodopoly(VDF-co-PMVE) copolymers ranging from 1000 to 18 000 g mol−1 (assessed by 19F NMR), produced for the first time. It was also noted that the higher the molar masses, the higher the amount of −CF2CH2−I end-group. The controlled behavior of that polymerization was also evidenced by the absence of the reversed −CH2CF2−CF2CH2− VDF dyads, narrow polydispersity indices (