A study of diffusional behavior of polymer having semiflexible main-chain with long n-alkyl side-chains as associated with structural behavior of the side-chains

Structural and dynamic characterizations of poly(n-octadecyl methacrylate)(PODMA) have been made at −8.2 and 13.6 °C below the melting temperature (Tm) of the n-octadecyl side-chain crystallite and at temperatures from 25.8 to 65 °C above the Tm of the n-octadecyl side-chain crystallite by 13C CP-MAS NMR, and have been made at temperatures from 30 to 80 °C by 13C DD-MAS NMR, respectively. Also, the 1H T2s of the n-octadecyl side-chain have been measured as a function of temperature in the temperature range from 20 to 80 °C by 1H spin-echo 1H NMR, and its dynamic behavior has been studied. Further, diffusional behavior of PODMA chains in the molten state at temperatures above the Tm of the n-octadecyl side-chain crystallite has been elucidated through determination of the diffusion coefficients (Ds) by means of pulsed field-gradient stimulated-echo (PFGStE) 1H NMR method. The existence of the two kinds of the Dslow component with the order of 10−11-10−10 cm2 s−1 as the major component and the Dfast component with the order of 10−7 cm2 s−1 as the minor component in diffusion process of PODMA chains in the molten state has been shown and further their diffusion behaviors have been discussed.