Studies on Sidechain Crystallization of Poly (γ-n-alkyl L-glutamate)

• Published in: KOBUNSHI RONBUNSHU Vol. 45; no. 1; pp. 69 - 77
• Main Authors: ONO, Hirofumi, ABE, Akihiro, WATANABE, Junji
• Format: Journal Article
• Language: Japanese
• Published: The Society of Polymer Science, Japan 01.01.1988
• Subjects: Poly (γ-alkyl L-glutamate); Sidechain Crystallization; Thermal Analysis; α-Helical Conformation
• ISSN: 0386-2186; 1881-5685
• DOI: 10.1295/koron.45.69

The sidechain crystallization of poly (γ-n-alkyl L-glutamate) s (PALG) with n=10 to 18 has been studied. X-Ray diffraction analysis indicates that the crystalline structures are triclinic for polymers with n≥14. Crystalline spacings were found to be nearly the same for all the samples investigated. A small odd-even oscillation with n was observed in thermodynamics quantities such as melting temperature, and the associated enthalpy and entropy changes. Such an odd-even effect may arise from the variation of the spatial orientation of the terminal bond of the sidechain: in solution, the orientational correlation between the α-helical axis and the terminal bond of the sidechain is known to exhibit an odd-even oscillation with n. The observed enthalpy ΔHf, and entropy of melting ΔSf are compared with those reported for the other polymer systems including poly (alkyl acrylate) s and poly (alkyl maleimide) s. It is concluded that the disorientation of sidechains is the major contributor to observed values of ΔHf and ΔSf.