Molecular α-relaxation process of exopolysaccharides extracted from Nostoc commune cyanobacteria
| Autor: | Fernando G. Torres, Omar P. Troncoso, Daniel López, Karen N. Gonzales |
|---|---|
| Přispěvatelé: | Pontificia Universidad Católica del Perú |
| Rok vydání: | 2020 |
| Předmět: |
Cyanobacteria
Dopin 02 engineering and technology Chemical Fractionation BDS Biochemistry Chloride 03 medical and health sciences chemistry.chemical_compound Exopolysaccharide Structural Biology medicine Molecular Biology 030304 developmental biology chemistry.chemical_classification Nostoc commune 0303 health sciences biology Spectrum Analysis Monosaccharides Polysaccharides Bacterial Doping Temperature General Medicine Polymer 021001 nanoscience & nanotechnology biology.organism_classification Ammonium iodide chemistry Chemical engineering α-Relaxation Relaxation (physics) Carboxymethylation 0210 nano-technology Glass transition medicine.drug |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| ISSN: | 0141-8130 |
| DOI: | 10.1016/j.ijbiomac.2020.07.268 |
| Popis: | Broadband dielectric spectroscopy was used to investigate the molecular α-relaxation of the exopolysaccharides (EPS) extracted from Nostoc commune cyanobacteria. The EPS were modified in different ways. EPS were carboxymethylated to obtain carboxymethyl-exopolysaccharides (CEPS). EPS and CEPS were doped with ammonium iodide and 1-butyl-3-methylimidazolium chloride. An α relaxation process was observed for all specimens. The temperature dependence of the relaxation times for pure and doped, EPS and CEPS polymers exhibited non-Arrhenius behavior. This relaxation process was associated with the glass transition of the complex heteropolysaccharides produced by the cyanobacteria. The molecular mobility at the glass transition, T, was affected by both the carboxymethylation treatment and the doping. The fragility index also decreased for the doped specimens, which may be attributed to an increase in the mobility of the polymer chains due to the plasticizing effect of the doping agents. The authorswould like to thank Prof. Carlos A. Stortz andDr.Diego A. Navarro for the monosaccharide compositions analysis of EPS. S. Rodriguez is greatly acknowledged for experimental assistance with the DSC tests. The authors acknowledge financial support received from the Vice-rectorate of Research of the Pontificia Universidad Católica del Perú (VRI-PUCP-695). |
| Databáze: | OpenAIRE |
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