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Degradation mechanisms of bioresorbable polyesters. Part 1, Effects of random scission, end scission and autocatalysis

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posted on 2017-10-02, 08:36 authored by Andy GleadallAndy Gleadall, Jingzhe Pan, Marc-Anton Kruft, Minna Kellomaki
A mathematical model was developed to relate the degradation trend of bioresorbable polymers to different underlying hydrolysis mechanisms, including noncatalytic random scission, autocatalytic random scission, noncatalytic end scission or autocatalytic end scission. The effect of each mechanism on molecular weight degradation and potential mass loss was analysed. A simple scheme was developed to identify the most likely hydrolysis mechanism based on experimental data. The scheme was first demonstrated using case studies, then used to evaluate data collected from 31 publications in the literature to identify the dominant hydrolysis mechanisms for typical biodegradable polymers. The analysis showed that most of the experimental data indicates autocatalytic hydrolysis, as expected. However, the study shows that the existing understanding on whether random or end scission controls degradation is inappropriate. It was revealed that pure end scission cannot explain the observed trend in molecular weight reduction because end scission would be too slow to reduce the average molecular weight. On the other hand, pure random scission cannot explain the observed trend in mass loss because too few oligomers would be available to diffuse out of a device. It is concluded that the chain ends are more susceptible to cleavage, which produces most of the oligomers leading to mass loss. However, it is random scission that dominates the reduction in molecular weight.

Funding

A.G. acknowledges an EPSRC PhD studentship.

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Published in

Acta Biomaterialia

Volume

10

Issue

5

Pages

2223 - 2232

Citation

GLEADALL, A. ... et al., 2014. Degradation mechanisms of bioresorbable polyesters. Part 1, Effects of random scission, end scission and autocatalysis. Acta Biomaterialia, 10 (5), pp.2223-2232.

Publisher

Elsevier (© Acta Materialia Inc.)

Version

  • AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2014

ISSN

1742-7061

eISSN

1878-7568

Language

  • en

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