Poly(epichlorohydrin) modified with 3,4,5-tris(dodecyloxi)benzoate: structure and dynamics of the aliphatic side-chains in the columnar mesophase

We investigated the dynamics and the structure of the aliphatic side chains of a random-grafted copolymer, obtained by chemical modification of poly(epichlorohydrin) (PECH) with potassium 3,4,5-tris(dodecyloxy)benzoate, by solid state 13C NMR. Below 283 K, the aliphatic chains partially crystallize in all-anti conformation. Calorimetric data are compatible with an orthorombic packing. Below 323 K, the polymer exhibits a columnar mesophase. Spin-lattice relaxation times T1C were determined in this temperature range and at 333 K, i.e. in the isotropic phase. In the liquid crystalline state, it was found that some carbons exhibit a double decay in the spin-lattice relaxation, which was attributed to presence of the LC phase. This hypothesis was supported by conformational analysis performed by molecular modelling. The activation energies of relaxation processes in the mesophase were also estimated.