title: Nanostructurated complexes of poly(beta,L-malate) and cationic surfactants: synthesis, characterization and structural aspects.
abstract: Ionic complexes of microbially produced poly(beta,L-malic acid) and alkyltrimethylammonium surfactants with linear alkyl chains containing even numbers of carbon atoms from 14 up to 22, were investigated. Complexes with a stoichiometric or nearly stoichiometric composition were prepared by precipitation from equimolar mixtures of aqueous solutions of the two components. All complexes were found to adopt supramolecular stratified structures made of alternating layers of poly(beta,L-malate) and surfactant with a periodicity on the length scale of 3-5 nm, which increased proportionally to the length of the polymethylene chain. In these complexes, alkyl side chains with more than 16 carbon atoms were partially crystallized showing reversible melting at temperatures between 40 and 70 degrees C. After melting, a smectic LC phase that isotropicized at approximately 100 degrees C was observed for all of the complexes. Conformational and dimensional changes taking place in the complexes by effect of heating were analyzed by (13)C CP-MAS NMR and powder X-ray diffraction.
authors.affiliation: Departament d'Enginyeria Química, Universitat Politècnica de Catalunya ETSEIB, Diagonal, 647, 08028 Barcelona, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Portilla-Arias
authors.forename: Montserrat
authors.initials: M
authors.lastname: García-Alvarez
authors.forename: Antxon
authors.initials: A
authors.lastname: Martínez de Ilarduya
authors.forename: Eggerhard
authors.initials: E
authors.lastname: Holler
authors.forename: Sebastián
authors.initials: S
authors.lastname: Muñoz-Guerra
mesh_terms: D002152:Calorimetry, Differential Scanning; D002412:Cations / Q000737:chemistry; D003460:Crystallization; D009682:Magnetic Resonance Spectroscopy; D008293:Malates / Q000737:chemistry*; D015394:Molecular Structure; D049329:Nanostructures / Q000737:chemistry*; D044367:Phase Transition; D011108:Polymers / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D002412:Cations; D008293:Malates; D011108:Polymers; D013501:Surface-Active Agents; C121060:poly(malic acid)