Rigid cyclic chains in solution: cyclic amylose carbamate derivatives*

Rigid cyclic polymers (cyclic amylose carbamate derivatives) were succsessfully synthesized from relatively flexible cyclic amylose for which degree of polymerization (DP) ranges between 30 and 300. The cyclic chains have lyotropic liquid crystallinity for which the phase diagram of isotropic and nematic phases were explained by a modified scaled particle theory when we assume some specific conformation in the nematic phase. The chain conformation of the cyclic polymers in dilute solution was determined by means of the small-angle X-ray scattering. The local helical structure for the cyclic polymers is appreciably extended and therefore the main chain is more flexible than that for the corresponding linear chain. We prepared chiral separation columns from the cyclic polymers. The conformational difference between linear and cyclic chains is affectable to the chiral separation ability. When we prepared partly substituted amylose derivative, the aqueous solution showed phase separation behavior, so called temperature responsive behavior. These samples still can form inclusion complex ability of iodine and some hydrophobic molecules. Interestingly, the coupling constant for the linear and cyclic chains are appreciably different, indicating the local conformational difference effects the inclusion complex ability of amylosic chains.