RAFT/MADIX (co)polymerization of vinyl trifluoroacetate: a means to many ends
In this study, RAFT/MADIX (co)polymerization of vinyl trifluoroacetate (VTFAc) is presented and the specific properties of the resulting polymers are discussed. Xanthate-mediated polymerization of VTFAc exhibits the features of a reversible-deactivation radical polymerization. The xanthate is responsible for a decrease in the overall rate of polymerization compared to conventional radical polymerization. In spite of a limited kinetic chain length mainly attributed to chain transfer to solvent, number-average molar masses increase with monomer conversion and dispersities remain very low (1.07< Đ <1.23) for theoretical Mn lower than 1.5 × 104 g mol−1. The obtained polymers are semi-crystalline with high melting points. The statistical copolymerization of vinyl acetate with VTFAc yields controlled polyvinyl esters with tunable thermal properties and tacticity. Well-defined PVAc-PVOH diblock copolymers are readily produced by selective methanolysis of the VTFAc units of the starting PVAc-PVTFAc diblock copolymer. The added value of VTFAc in the design of polyvinyl esters with enhanced CO2-philicity is also explored through its copolymerization with vinyl pivalate. VTFAc is seen as a new multifaceted partner in the chemistry of controlled poly(vinyl esters) that can be used to finely tune polymer dispersity, tacticity, thermal properties, chemical stability and solubility in supercritical carbon dioxide.