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Kinetics of γ‐benzyl‐ L ‐glutamate NCA's polymerizations and molecular‐weight distributions on corresponding polymers
Author(s) -
Rinaudo M.,
Domard A.
Publication year - 1976
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1976.360151107
Subject(s) - chemistry , kinetics , dispersity , polymerization , polymer , molar mass distribution , polymer chemistry , solvent , degree of polymerization , reaction rate constant , organic chemistry , physics , quantum mechanics
Abstract The kinetics of γ‐benzyl‐ L ‐glutamate NCA's polymerizations in dioxane as solvent are discussed. The partial orders respective to [A], the NCA concentration and [ I 0 ], the initial initiator concentration are given; the rate constants are deduced and a mechanism is proposed to justify a rate of polymerization V p = k [A][ I 0 ] 2 . The dependence of the rate constants on the conformation of the growing chains is demonstrated; the acceleration is attributed to the ordered structures favorable to hydrogen bonding. The kinetics of aging have also been examined and discussed; it is shown that they cannot modify the kinetics of polymerization. The DP n were obtained on the same samples before and after debenzylation; it is proved that at any concentration, DP n ≃ [A 0 ]/[ I 0 ]. The molecular‐weight distributions were obtained by chromatography and a polydispersity lower than 1.3 was deduced for each sample. The trimodal distribution, appearing as soon as [ A 0 ]/[ I 0 ] is larger than 3, is attributed to the existence of the three structures σ, β, and α. The weight fraction of each of the structures was correlated to the kinetics of polymerization.