Hydrolytic and enzymatic degradation of biobased poly(4-hydroxybutyrate) films. Selective etching of spherulites
| Autor: | Pau Turon, Lourdes Franco, Jordi Puiggalí, Juan Carlos Martínez, Ina Keridou, Lutz Funk, Luis J. del Valle |
|---|---|
| Přispěvatelé: | Universitat Politècnica de Catalunya. Departament d'Enginyeria Química, Universitat Politècnica de Catalunya. PSEP - Polimers Sintètics: Estructura i Propietats. Polimers Biodegradables |
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Polímers--Biodegradació
Materials science Hydrolytic degradation Thermal properties Polymers and Plastics Rhizopus oryzae Anàlisi enzimàtica 02 engineering and technology 010402 general chemistry 01 natural sciences Biodegradable polymers chemistry.chemical_compound Crystallinity Enginyeria química [Àrees temàtiques de la UPC] Enzymatic degradation Materials Chemistry Lamellar structure Enzymatic analysis Microstructure Polymers--Biodegradation Films biology Small-angle X-ray scattering Poly(4-hydroxybutyrate) 021001 nanoscience & nanotechnology Condensed Matter Physics biology.organism_classification Biodegradable polymer 0104 chemical sciences Amorphous solid Monomer Chemical engineering chemistry Mechanics of Materials Degradation (geology) 0210 nano-technology |
| Zdroj: | UPCommons. Portal del coneixement obert de la UPC Universitat Politècnica de Catalunya (UPC) |
| Popis: | Hydrolytic degradation of poly(4-hydroxybutyrate) (P4HB) films has been studied considering media of different pH values (i.e., 3, 7 and 10) and temperatures (i.e., 37 and 55 °C). Enzymatic degradation has also been evaluated at physiological conditions using two different lipases: Pseudomonas cepacia and Rhizopus oryzae. Different bulk and surface erosion mechanisms with random chain scissions and successive removal of monomer units have been supported through weight loss measurements, molecular weight determinations by GPC and NMR spectroscopy and changes on thermal properties by DSC. Thermal annealing during exposure to different media and even degradation influenced on the melting temperature and crystallinity of samples, as well as on the lamellar geometrical parameters as evaluated by SAXS. Enzymatic degradation was ideal to selectively eliminate the amorphous regions and highlight the spherulitic morphology. Presence of ringed textures were therefore evident in bright field optical micrographs in addition to SEM images, namely observations under polarized light was not necessary to distinguish the presence of banded spherulites. Rhizopus oryzae was revealed to be the most suitable enzyme to crop out the P4HB spherulites that form part of the initial smooth surfaces of solvent casting films. After determining the appropriate activity and exposure time, the presence of rings constituted by cooperative C-shaped edge-on lamellae and flat-on lamellae was highlighted. |
| Databáze: | OpenAIRE |
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