Comblike Complexes of Bacterial Poly(,D-glutamic acid) and Cationic Surfactants
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- 作者：Graciela Pé ; rez-Camero ; Montserrat Garcí ; a-Alvarez ; Antxon Martí ; nez de Ilarduya ; Carlos Ferná ; ndez ; Lourdes Campos ; and Sebastiá ; n Muñ ; oz-Guerra
- 刊名：Biomacromolecules
- 出版年：2004
- 出版时间：January 2004
- 年：2004
- 卷：5
- 期：1
- 页码：144 - 152
- 全文大小：301K
- 年卷期：v.5,no.1(January 2004)
- ISSN：1526-4602
文摘
The ability of microbially produced poly(
,D-glutamic acid) to form stable polyelectrolyte-opposite chargedsurfactant complexes was investigated. A sonicated sample of polyacid with a molecular weight about 105Da and a content of D enantiomer higher than 90% was used in this study. Nearly stoichiometric complexesof poly(,D-glutamate) anions and alkyltrimethylammonium cations bearing linear alkyl chains with evennumbers of carbon atoms from 12 up to 22 were "synthesized" by precipitation from equimolar mixtures ofaqueous solutions of the two components. All complexes were found to adopt stratified supramolecularstructures made of alternating layers of poly(,D-glutamate) and surfactant with a periodicity increasingfrom 3.2 up to 4.3 nm according to the length of the alkyl side chain. No definite evidence indicative of theconformation adopted by the main chain in these complexes could be afforded. In all cases, the alkyl chainsare in an extended conformation and oriented normal or nearly normal to the layer planes. Polymethylenechains with more than 16 carbon atoms were partially crystallized in the complexes in a separated paraffinicphase, whereas no crystallinity was detected for shorter lengths. The crystallized paraffinic phases werefound to melt reversibly at temperatures between 40 and 70 
C. This process was found to happen with aconcomitant expansion-contraction that amounts between 2 and 8% of the long period of the structure butwithout significant alteration of the layered arrangement.
,D-glutamic acid) to form stable polyelectrolyte-opposite chargedsurfactant complexes was investigated. A sonicated sample of polyacid with a molecular weight about 105Da and a content of D enantiomer higher than 90% was used in this study. Nearly stoichiometric complexesof poly(,D-glutamate) anions and alkyltrimethylammonium cations bearing linear alkyl chains with evennumbers of carbon atoms from 12 up to 22 were "synthesized" by precipitation from equimolar mixtures ofaqueous solutions of the two components. All complexes were found to adopt stratified supramolecularstructures made of alternating layers of poly(,D-glutamate) and surfactant with a periodicity increasingfrom 3.2 up to 4.3 nm according to the length of the alkyl side chain. No definite evidence indicative of theconformation adopted by the main chain in these complexes could be afforded. In all cases, the alkyl chainsare in an extended conformation and oriented normal or nearly normal to the layer planes. Polymethylenechains with more than 16 carbon atoms were partially crystallized in the complexes in a separated paraffinicphase, whereas no crystallinity was detected for shorter lengths. The crystallized paraffinic phases werefound to melt reversibly at temperatures between 40 and 70 C. This process was found to happen with aconcomitant expansion-contraction that amounts between 2 and 8% of the long period of the structure butwithout significant alteration of the layered arrangement.