Mesomorphic phase in oriented poly(pentamethylene 2,6-naphthalate)

The mesomorphic structure of poly(pentamethylene 2,6-naphthalate) (PPN) was investigated using a synchrotron X-ray scattering. The PPN fibers cold-drawn from the super-cooled amorphous state showed a smectic mesomorphic structure and further a crystalline phase at high strain. Based on the experimental evidence showing the split of amorphous halo up and down the equator and the conformational constraint suggested by the crystal structure refinement and computation, we suggested the smectic phase as SCA where the mesogens are tilted against the layer surface normal and the tile direction is opposite between the neighboring layers.