The β-conformation and association of low-molecular-weight poly-γ-benzyl-L-glutamate in Solutions

✍ Scribed by Shoichi Ikeda; Toyoko Imae

• Publisher: Wiley (John Wiley & Sons)
• Year: 1972
• Tongue: English
• Weight: 701 KB
• Volume: 11
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1972.360110214

✦ Synopsis

Three samples of poly--phensyl-L-glutamate have been prepared from r-henzyl-,Vcarhoxy-L-glutamate anhydride with n-hexylamine initiation a t anhydride-to-initiator molar ratios, [A]/[I], of 3, 4, and 8, and their conformation and association in ethylene dichloride and dioxane have been investigated by means of infrared spectra and vaporpressure osmometry. Two conformations, u-and p-forms, are present in those solvents, and the content of B-form increases with increasing A/I value and concentration. At infinite dilution molecular association is absent, but the number-average molecular weight increases with concentration, markedly in ethylene dichloride and, to a lesser extent, in dioxane. The fraction of residues involved in associated molecules have been estimated as a function of concentration. Combination of the content of 0-structure with the fraction of association leads to the following results. The A/I 3 and 4 polymers form intermolecularly hydrogen-bonded aggregates, in which hydrogen-bonded residues are in the p-structure. The A/I 8 polymer has the intramolecularly hydrogen-bonded 0-structure a t very low concentrations, but it also forms intermolecularly hydrogenbonded aggregates a t high concentrations.