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Abstract
Nematic-isotropic transition temperature, Ti , was measured as a function of heating rate for main chain polyethers containing either δ-methylstilbene (HMS) or 1-(4-oxyphenyl)-2-(2-methyl-4-oxyphenyl)ethane (MBPE) and flexible aliphatic spacers. At the heating rate of 40°C/minute Ti was found to increase by up to 15°C for HMS polymers, after instrumental correction. Superheating was greatly promoted by increased molecular weight and chain rigidity. The phenomenon is consistent with the previously observed memory effect in the isotropic and nematic phases and is attributed to the diffusion controlled change in overall chain dimensions accompanying the nematic-isotropic transition.