dc.contributor.author Shmool, Talia en dc.contributor.author Zeitler, Axel en dc.date.accessioned 2019-01-22T00:30:55Z dc.date.available 2019-01-22T00:30:55Z dc.date.issued 2019-01-21 en dc.identifier.issn 1759-9954 dc.identifier.uri https://www.repository.cam.ac.uk/handle/1810/288301 dc.description.abstract The mechanical properties of an amorphous copolymer are directly related to the dynamic processes occurring at the molecular level. Poly lactic-co-glycolic acid (PLGA) is a biodegradable co-polymer, and in this work we investigate the dynamics of PLGA and its glass transition behaviour by performing variable temperature terahertz time-domain spectroscopy (THz-TDS) experiments. We correlate PLGA dynamics, as measured at terahertz frequencies, their temperature dependence, molecular weight (MW), lactide to glycolide ratio, and free volume. The THz-TDS data can be used to detect two distinct transition processes, $T_{\beta}$ and $T_{g,\alpha}$. To complement our analysis, we use dynamic mechanical analysis (DMA) to probe the $\beta$- and $\alpha$-relaxation processes in PLGA, and compare the results obtained from the DMA experiments with those obtained using THz-TDS. The values of $T_{g,\alpha}$, as determined from the THz-TDS experiments, are in good agreement with $T_{g,\text{DSC}}$, determined by calorimetric measurements, and with $T_{g,\text{DMA}}$, determined by the DMA measurements. We attribute $T_{\beta}$ to the change in dipole moments associated with the $\beta$-relaxation process, originating from the local rotation of C-O macromolecular chain segments, and $T_{g,\alpha}$ to the change in dipole moments due to large segmental motion of the copolymer backbone associated with the $\alpha$-relaxation process. By showing experimental temperature-dependent results from THz-TDS and DMA for PLGA, we demonstrate that the behaviour of PLGA is in line with the potential energy surface interpretation by Goldstein as well as the free volume theory of Fox and Flory, and that both concepts together can be used to understand amorphous polymers. dc.publisher Royal Society of Chemistry (RSC) dc.title Insights into the structural dynamics of poly lactic-: Co -glycolic acid at terahertz frequencies en dc.type Article prism.endingPage 361 prism.issueIdentifier 3 en prism.publicationDate 2019 en prism.publicationName Polymer Chemistry en prism.startingPage 351 prism.volume 10 en dc.identifier.doi 10.17863/CAM.35617 dcterms.dateAccepted 2018-11-30 en rioxxterms.versionofrecord 10.1039/c8py01210e en rioxxterms.version AM rioxxterms.licenseref.uri http://www.rioxx.net/licenses/all-rights-reserved en rioxxterms.licenseref.startdate 2019-01-21 en dc.contributor.orcid Shmool, Talia [0000-0002-0415-3050] dc.contributor.orcid Zeitler, Axel [0000-0002-4958-0582] dc.identifier.eissn 1759-9962 rioxxterms.type Journal Article/Review en pubs.funder-project-id EPSRC (1198) cam.orpheus.success Thu Jan 30 10:53:24 GMT 2020 - Embargo updated * rioxxterms.freetoread.startdate 2020-01-21
﻿