Title
Hydrolytic and enzymatic degradation of biobased poly(4-hydroxybutyrate) films. Selective etching of spherulites
Date Issued
01 January 2021
Access level
open access
Resource Type
journal article
Author(s)
Universitat Politècnica de Catalunya
Publisher(s)
Elsevier Ltd
Abstract
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.
Volume
183
Language
English
OCDE Knowledge area
Ciencia de los polímeros
Ingeniería química
Subjects
Scopus EID
2-s2.0-85097572355
Source
Polymer Degradation and Stability
ISSN of the container
01413910
Sponsor(s)
The authors acknowledge support from MINECO and FEDER (RTI2018-101827-B-I00), and the Generalitat de Catalunya (2017SGR373). I.K. also acknowledges the financial support from B. Braun Surgical S.A. Diffraction experiments were performed at the NCD-SWEET beamlines at ALBA Synchrotron with the collaboration of ALBA staff.
Sources of information:
Directorio de Producción Científica
Scopus