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Production of polylactic acid aerogels via phase separation and supercritical CO2 drying: thermodynamic analysis of the gelation and drying process
Citation Link: https://doi.org/10.15480/882.3888
Publikationstyp
Journal Article
Publikationsdatum
2021-09-09
Sprache
English
Institut
Enthalten in
Volume
56
Issue
34
Start Page
18926
End Page
18945
Citation
Journal of Materials Science 56 (34): 18926-18945 (2021-12-01)
Publisher DOI
Scopus ID
Publisher
Springer Science + Business Media B.V
The application range of aerogels, especially in the life-science sector, can be extended by utilizing biocompatible polymers such as polylactic acid (PLA). However, the low glass transition temperature (Tg) of PLA and the challenging gelation techniques limit the application of supercritical CO2 (scCO2) drying and thus the PLA-aerogel production. The aim of this work is to overcome this challenge and to provide a better understanding of the thermodynamics of the process. Therefore, the gelation of amorphous PLA (PDLLA) and semicrystalline PLA (PLLA) via thermal-induced phase separation (TIPS) was studied. To identify polymer/solvent/antisolvent ratios suitable for gelation, thermodynamic modeling (PC-SAFT) was used to describe the corresponding ternary phase diagrams. scCO2 drying was used to preserve the mesoporous gel structure formed during the gelation. Due to the decrease in the Tg of PLA in the presence of CO2, this could not be applied to all gels. It was found that the critical parameter to enable the scCO2 drying of low Tg polymers is the crystallinity degree (Xc) of the polymer. Based on these results, some guidelines for producing aerogels from polymers with low Tg are formulated. Graphical abstract: [Figure not available: see fulltext.]
DDC Class
540: Chemie
600: Technik
Funding Organisations
More Funding Information
This research was supported by the Deutsche Forschungsgemeinschaft, DFG, project number SM 82/16-1, SA 700/22-1 and EN 291-10-1.