Interplay between Structure and Dynamics in Chitosan Films Investigated with Solid-State NMR, Dynamic Mechanical Analysis, and X-ray Diffraction

ABSTRACT: Modern solid-state NMR techniques, combined with X-ray diffraction, revealed the molecular origin of the difference in mechanical properties of self-associated chitosan films. Films cast from acidic aqueous solutions were compared before and after neutralization, and the role of the counterion (acetate vs Cl) was investigated. There is a competition between local structure and long-range order. Hydrogen bonding gives good mechanical strength to neutralized films, which lack long-range organization. The long-range structure is better defined in films cast from acidic solutions in which strong electrostatic interactions cause rotational distortion around the chitosan chains. Plasticization by acetate counterions enhances long-range molecular organization and film flexibility. In contrast, Cl counterions act as a defect and impair the long-range organization by immobilizing hydration water. Molecular motion and proton exchange are restricted , resulting in brittled films despite the high moisture content.

• Autores: Gartner Vargas, Carmiña; Lopez Osorio, Betty Lucy; Sierra García, Ligia; Graf, Robert; Spiess, Hans W.; Gaborieau, Marianne
• Tipo de recurso: Article of investigation
• Fecha de publicación: 2011
• Institución: Universidad de Antioquia
• Repositorio: Repositorio UdeA
• Idioma: eng
• OAI Identifier: oai:bibliotecadigital.udea.edu.co:10495/39512
• Acceso en línea: https://hdl.handle.net/10495/39512
• Palabra clave: Quitosano - química; Chitosan - chemistry; Espectroscopía de Resonancia Magnética; Magnetic Resonance Spectroscopy; Difracción de Rayos X; X-Ray Diffraction; https://id.nlm.nih.gov/mesh/D048271; https://id.nlm.nih.gov/mesh/D009682; https://id.nlm.nih.gov/mesh/D014961
• Rights: openAccess
• License: https://creativecommons.org/licenses/by-nc-nd/4.0/