FTIR spectroscopy studies on the spontaneous neutralization of chitosan acetate films by moisture conditioning
| Autor: | J. Gabriel Luna-Bárcenas, Reina Araceli Mauricio-Sánchez, Ricardo Salazar, Arturo Mendoza-Galván |
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| Rok vydání: | 2018 |
| Předmět: |
Moisture
Water activity Inorganic chemistry Moisture sorption isotherm technology industry and agriculture Protonation 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Chitosan chemistry.chemical_compound Acetic acid chemistry Carboxylate Fourier transform infrared spectroscopy 0210 nano-technology Spectroscopy |
| Zdroj: | Vibrational Spectroscopy. 94:1-6 |
| ISSN: | 0924-2031 |
| Popis: | The influence of moisture ambiance on the spontaneous neutralization of amorphous chitosan acetate films during storage at 30 °C and water activities (aw) in the range of 0.11 to 0.84 is studied by Fourier transform infrared (FTIR) spectroscopy. Three ranges of relative humidity affecting the chitosan acetate films are identified: i) 0.11 ≤ aw ≤ 0.32, produces dehydration and partial neutralization; ii) aw = 0.44 and 0.55, spontaneous neutralization and rearrangement of OH bonds; iii) 0.64 ≤ aw ≤ 0.85, prevalence of films in the acetate form and moisture absorption. Acetate content of films as function of water activity and storage time is assessed from the band accounting for the electrostatic interaction of protonated amine groups (–NH3+) in chitosan and carboxylate ions (–COO−) of acetic acid. FTIR spectroscopy results are correlated with the equilibrium properties determined from moisture sorption isotherm. The simple method presented may help to produce chitosan acetate films with tuned protonation degree that are relevant in many applications such as biomedical, food, cosmetics, and pharmaceutical. |
| Databáze: | OpenAIRE |
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