Poly(vinylidene fluoride)- b -poly(styrene) Block Copolymers by Iodine Transfer Polymerization (ITP): Synthesis, Characterization, and Kinetics of ITP

The syntheses of poly(vinylidene fluoride)- b -poly(styrene) (PVDF- b -PS) block copolymers, from the iodine transfer polymerization (ITP) of styrene, in the presence of PVDF−I, are presented. In a first step, considering that the radical polymerization of vinylidene fluoride can lead to two different isomeric oligomers, bearing either −CH 2 I or −CF 2 I end groups, the kinetics of ITP of styrene in the presence of two chain transfer agents, C 6 F 13 −CH 2 CF 2 −I and HCF 2 −CF 2 CH 2 −I, were achieved as model reactions. The characterization of sampled aliquots by 19 F NMR spectroscopy could monitor the average degree of polymerization in number (DP n ) vs styrene conversion (α Styrene ). ITPs of styrene with both these chain transfer agents showed two opposite behaviors, also confirmed by MALDI−TOF spectroscopy and SEC chromatography. (i) on the one hand, in the presence of C 6 F 13 −CH 2 CF 2 −I, the controlled character of ITP of styrene was evidenced (a linear dependence of DP n vs α Styrene was observed), theoretical DP n values were close to those of the targeted ones, with low polydispersity indexes (PDI = 1.5) and the transfer constant value was assessed ( C Tr ≅ 1); (ii) on the other hand, using HCF 2 −CF 2 CH 2 −I as the chain transfer agent, ITP of styrene did not occur since only a direct initiation for the polymerization of styrene was noted, with DP n value higher than the targeted one and a broad polydispersity distribution (PDI > 2). In a second part, PVDF- b -PS block copolymers were synthesized via a two step-procedure, ITP of VDF in the presence of C 6 F 13 I as the chain transfer agent leading to C 6 F 13 (VDF) n −I oligomers and, subsequently, ITP of styrene using those latter oligomers as macromolecular chain transfer agents. These block copolymers were characterized by 19 F and 1 H NMR and MALDI−TOF spectroscopies, and by SEC chromatography. Their morphological and thermal properties were also studied by atomic force microscopy (AFM) and by differential scanning calorimetry (DSC), respectively.