The effect of poly(glycerol sebacate) stoichiometry on its physical characteristics

Abstract

Event Abstract Back to Event The effect of poly(glycerol sebacate) stoichiometry on its physical characteristics Brendan Nicholson1, Jeremy J. Harris1 and Julia Donnelly1 1 Secant Medical, Inc., United States Introduction: Poly(glycerol sebacate) (PGS) has gained much attention in the area of regenerative medicine and the majority of studies have focused on the polymer synthesized from an equimolar ratio of sebacic acid to glycerol. However, unequal stoichiometric ratios could produce polymers that have advantageous chemical and physical properties. Based on our analysis of PGS synthesized from varying monomer stoichiometries, we hypothesize that the physical properties of the resultant PGS will be tunable to allow for applications to a wider range of tissue engineering applications. Materials and Methods: All PGS was synthesized via a polycondensation reaction between glycerol and sebacic acid. Reactors were charged with variable molar ratios of glycerol to one molar equivalent of sebacic acid and 3 molar equivalents of water. The ratios of glycerol to sebacic acid were 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, and 1.3. The reactors were heated to 140°C under flow of N2 and stirred until the sebacic acid was melted. The temperature was then set to 120°C and held under N2 flow for 24 hours, then 130°C and under vacuum (~10 Torr) for 26 hours. The resultant resins were characterized by gel permeation chromatography (GPC), residual acid value titration, and oscillatory rheometry. Results and Discussion: GPC chromatograms (Fig. 1) of the PGS resins show a trend of decreasing Mw and Mw/Mn values with increasing glycerol:sebacic acid ratio. This indicates that the polymer chains self-terminate in excess glycerol, leading to a higher concentration of low Mw polymers. This is confirmed by the residual acid value titration showing a trend of decreasing residual acid with increasing glycerol content. Oscillatory rheometry amplitude sweeps (Fig. 2) performed at 25°C show increasing storage (G') and loss (G") moduli with increasing glycerol ratio. At ratios above 0.8, G' dominates G" resulting in an elastic solid. The yield strain of the polymer also increases with increasing glycerol, indicating that the elasticity of the polymer is increasing. Conclusions: Polymerization of PGS with varied monomer stoichiometric ratios results in a change of the physical characteristics of the resulting polymer. Acid values, Mw, and elasticity decreased and stiffness increased with increasing glycerol:sebacic acid ratios. PGS synthesized with equimolar glycerol:sebacic acid ratio exhibits a fixed relationship between Mw, acid value, and mechanical properties. Adjusting the glycerol:sebacic acid ratio shows the possibility to tune the molecular weight and mechanical properties of the polymer independently of the acid functionality. In addition to controlling the Mw of PGS, the functional group concentration (acid number) can also be tuned to allow for varying concentrations of additives to be covalently bound to the polymer matrix. This can have a broad impact on the tunability of PGS through changes in Mw, elasticity, degradation, and release kinetics of loaded drugs for various tissue engineering applications. Keywords: Functionalization, material design, Biodegradable material, Polymeric material Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: Poster Topic: Biodegradable polymers Citation: Nicholson B, Harris JJ and Donnelly J (2016). The effect of poly(glycerol sebacate) stoichiometry on its physical characteristics. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.00096 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Brendan Nicholson Jeremy J Harris Julia Donnelly Google Brendan Nicholson Jeremy J Harris Julia Donnelly Google Scholar Brendan Nicholson Jeremy J Harris Julia Donnelly PubMed Brendan Nicholson Jeremy J Harris Julia Donnelly Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.