ISSN:
0360-6376
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A number of multi-N∊-poly(γ-benzyl-L-glutamyl)copoly(L-lysine γ-methyl-L-glutamate)s with branches having various degrees of polymerization and with various intervals of the grafting sites in the core molecule were prepared in N,N-dimethylformamide containing dimethyl sulfoxide by the reaction of N-carboxy anhydride of γ-benzyl L-glutamate with random copoly(L-lysine γ-methyl-L-glutamate)s of different composition with various anhydride-initiator ratios. The relationship between the intrinsic viscosity measured in a coil solvent, dichloroacetic acid (DCA), and the number-average molecular weight determined by osmometry was found to be expressed by the Mark-Houwink-Sakurada equation for the multichain copoly(α-amino acid)s which were made from the same polymeric initiator. The observed α values of the multichain copoly(α-amino acid)s in the equation were lower than that of linear poly(γ-benzyl-L-glutamate). The solvent induced helix-coil transition of the multichain copolymer was investigated in the chloroform-DCA system by the ORD technique. Two kinds of transition regions were clearly distinguished: The α-helices of the core molecules underwent the transition at lower DCA concentration and those of the branch chains at higher DCA concentration. The reduced viscosity of the multichain copoly-(α-amino acid) increased slightly between the two transition regions, in contrast to the large decrease in the reduced viscosity of linear poly(γ-benzyl-L-glutamate) during the helix-coil transition.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1978.170160817
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