Abstract
RAFT polymerization of vinylidene fluoride (VDF), leading to relatively well defined poly(vinylidenefluoride) (PVDF), is negatively affected by chain inversion resulting in less easily reactivatable PVDFT-XAdormant chains (terminated with the tail end of an inversely added VDF unit; XA = xanthate moiety).Although slow reactivation of these chains by PVDF• radicals (in contrast to general belief) was recentlydemonstrated, slow radical exchange leads to progressive loss of chain growth control. This article dealswith the possibility of synthesizing block copolymers from PVDF-XA macroCTAs by sequential addition.The investigations show that only PVDFH-XA (chains terminated with the head end of regularly addedVDF) can be reactivated by PNVP• (poly(N-vinylpyrrolidone)) radicals and that PVDFT-XA chains are completelyunreactive in the presence of PNVP•, PB• (poly(butylacrylate)) or PDM• (poly(N,N’-dimethylacrylamide)).However, both PVDFH-XA and PVDFT-XA can be reactivated by PVAc• (poly(vinyl acetate))radicals. The reactivation of the PVDFT-XA, albeit slower than that of the PVDFH-XA, is sufficiently fast toallow the synthesis of unprecedented well-defined PVDF-b-PVAc block copolymers with relatively highend-group fidelity. DFT calculations rationalize this behavior on the basis of faster radical exchange in theorder PVDFH-XA/VAc > PVDFH-XA/NVP > PVDFT-XA/VAc ≫ PVDFT-XA/NVP. The success of the chainextension also relies on faster activation relative to homopropagation of the chain extending monomer, aswell as fast addition of the released PVDF•H and PVDF•T to the monomer.