Macromolecules, 2019, vol 52, 23, pp. 9199-9207
DOI:10.1021/acs.macromol.9b01559
Abstract
The synthesis and structural characterization of linear PolyC3 polymers containing trimethylene-1,1-dicarboxylate structural repeat units with C6F13 and C8F17 fluorinated side chains is described for the first time, and their properties were compared with the traditional polyvinyl structures that display the fluorinated chain on every second rather than on every third carbon alongside the backbone. Homopolymers as well as statistical and block copolymers with n-propyl and/or allyl trimethylene-1,1-dicarboxylate blocks have been obtained from PolyC3 precursors containing diallyl trimethylene-1,1-dicarboxylate units, by reacting C6F13C2H4SH and C8F17C2H4SH thiols with the allyl groups using a thiolene post-polymerization modification reaction. Solid-state properties have been investigated by differential scanning calorimetry for all of the (co)polymers and by small-angle X-ray scattering/wide-angle X-ray scattering for the C8F17 homopolymer at several temperatures. The structure of the homopolymer consistently shows a coexistence of two smectic phases at room temperature, which can be identified as SmB and SmC. This coexistence is assumed to arise from the fact that the distances between carboxylic oxygens bonded to the same carbon are very close to the ones between the neighboring carboxylic oxygens alongside the backbone, resulting in two possible ways of packing the pendent fluoroalkyl chains arranged in a hexatic order.
