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Poly(γ‐ p ‐nitrobenzyl‐ L ‐glulainate): synthetic aspects, sedimentation, and viscosity studies
Author(s) -
Feyen J.,
De Groot K.,
De Visser A. C.,
Bantjes A.
Publication year - 1971
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.360101212
Subject(s) - dichloroacetic acid , chemistry , nitrobenzene , intrinsic viscosity , sedimentation coefficient , monomer , polymerization , dimethylformamide , polymer chemistry , inherent viscosity , triethylamine , viscosity , polymer , organic chemistry , solvent , thermodynamics , physics , catalysis , enzyme
A series of poly(γ‐ p ‐nitrobenzyl‐ L ‐glutamates), PNBG, has been synthesized by the polymerization of N ‐carboxyanhydride (NCA) derivatives of γ‐ p ‐nitrobenzyl‐ L ‐glutamate, NBG, using triethylamine as an initiator. We studied the influence of (a) the solvents dioxane, nitrobenzene, dimethylformamide (DMF), and DMF–1,2‐dichloroethane mixture and (b) the anhydride–initiator ratio (A/I) for the polymerization in nitrobenzene (A/I varying from 50 to 750) on the properties of the polymers obtained. In order to improve its synthesis, NBG, was prepared by three different methods. Ten samples of PNBG, ranging in M w from 10,000 to 50,000, were examined viscometrically in DMF and dichloroacetic acid (DCA) and by ultracentrifugation in DMF. The data for [η] and S o (limiting sedimentation coefficient) as functions of M w for PNBG in DMF were utilized, applying theories of Kuhn and Kuhn, 13 Schachman, 14 and Perrin, 15 for the estimation of the length per monomeric residue h. Viscosity data gave a h value of about 2.3 Å, Whereas sedimentation yielded 1.5 Å. Treating viscosity and sedimentation data for poly(γ‐benzyl‐ L ‐glutamate), PBLG, in the same way leads to somewhat higher h values (2.4 Å and 1.7 Å, respectively). Although a nitroaromatic effect was shown to be absent for PNBG in DMF, it can be concluded that in this medium PNBG has a somewhat more compact structure than PBLG.