Polymeric fibers and microporous films by photo-crosslinking of triphenylene-derived liquid crystals

Two series of photoreactive discotic liquid crystals consisting of a triphenylene core and six cinnamate units with one (TPC1(n)) or two (TPC2(n)) n-alkoxy groups (CnH2n+1O; n = 10-14), respectively, as peripheral groups are synthesized. Both of them are polymerized into fibers up to 2 mm long by UV irradiation in liquid paraffin in the columnar LC temperature ranges. The fiber structures seem to be preconstructed in liquid paraffin. In addition, TPC2(n) are shown to form microporous films up to 15 mu m in diameter by simply casting the solutions of some solvents followed by drying for several minutes in air at room temperature. Photoirradiation of the films in the LC temperature range converts them to polymeric ones while preserving the microporous and hexagonally ordered structure. From comparison with TPC1(n) and the hydrogenated derivative of TPC2(12), the porous film-forming property is suggested to result from the combination of the double bond of the cinnamoyl group and the two long alkoxy chains on the phenyl ring. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 605-612