Thermal-mechanical behavior of bio-enhanced vitrimers

Abstract

Today, vitrimer is a hot topic in polymer material research because it not only has good mechanical properties, but also can be repeatedly processed and recycled, thus solving the problem that plastics have always been unfriendly to the environment. Since 2011, a variety of vitrimer materials based on different dynamic associative exchange reactions have been developed. And the epoxy-acid polymer networks are one of the most common vitrimer structures, which can achieve the vitrimer behaviour with the help of catalyst. Compared with most plastics, bio-based materials can be relatively low toxicity and less effect to the environment. In addition, the improvement of catalyst will further expand the application of transesterification-based vitrimer by retaining biocompatibility. However, only a few examples of bio-based epoxy-acid vitrimers have been reported in the literature1,2. In this project, a common commercial lipase AE07 was used to catalyse the transesterification reaction of the sebacic acid (SA)/diglycidyl ether of bisphenol A (DGEBA) based polymer instead of the traditional inorganic catalyst in order to achieve a bio-enhanced associative covalent adaptive networks (CANs). The overall objective of this project is to develop and assess a bio-enhanced vitrimer from bio-sourced materials. It was found that even though lipase is sensitive to the temperature, the produced material still kept constant cross-link densities at elevated temperature and showed silica-like temperature-dependent viscosity behaviour (Arrhenius type). In addition, the catalyst loading can affect the thermal-mechanical properties of the lipase-catalysed product and different catalyst loading showed different CAN activation energy, ranging from 43 kJmol-1 to 69 kJmol-1. The idea of enzyme catalysed epoxy-acid polymer is an innovative and pioneering combination and it is not expensive and easy to prepare; thus, it is a promising material for the future application.

Date of Award	31 Aug 2021
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Brian Saunders (Supervisor) & Lee Fielding (Supervisor)