A small angle neutron scattering study of the effect of molecular weight on the conformation of side chain liquid crystal polymers in a smectic phase

The Small Angle Neutron Scattering (SANS) from specifically deuterated samp les of side-chain liquid crystal polymers has been used to determine the di mensions of the backbone both parallel and perpendicular to the director as well as the degree of polymerisation. It has been possible to determine th e effect of molecular weight on the chain dimensions in the smectic phase. There is strong anisotropy of the backbone conformation and it becomes stro nger as the molecular weight increases. This means that the tendency for th e chains to be confined between the smectic layers is stronger for larger m olecular weight polymers.