Synthesis and Applications of Sustainable Polymers with Branched and Cyclic Architectures

: (Alternative Format Thesis)

Abstract

The work discussed herein is centred upon the synthesis and potential applications of bio-based polymers with atypical polymer architectures. The indispensable nature of plastics in our day-to-day lives has led to concerns over environmental issues and resource depletion of non-renewables. While bio-based and biodegradable plastics could be key to a transition towards a more circular plastics economy, they currently lack the range of properties needed to replace current petroleum-derived offerings in many applications. To access greater market penetration, more diverse materials are required. Hence, two major portions of work were conducted with the aim of exploring the use of polymer topology to broaden the applicability of bio-based polymers.

First, cyclic polymers and copolymers of lactide (Chapter 3) and ε-decalactone (Chapter 4) were synthesised with the aim of furthering recent synthetic developments made in cyclic polymerisations. These included the development of stereoselective catalysts for cyclic polymerisation of rac-lactide, stereoblock copolymers of L- and D-lactide and multiblock copolymers of ε-decalactone, L-lactide and D lactide, all of which have not been reported in literature to our knowledge following a review of bio-based cyclic aliphatic polyesters included in Chapter 1. The physical, thermal and mechanical properties of these samples were compared to linear analogues and potential applications were discussed following this. Additionally, Small Angle Neutron Scattering (SANS) experiments were conducted on cyclic and linear polymer samples, with the aim of evaluating polymer-solvent interactions and chain scaling exponents (Chapter 5).

Secondly, a more specific project was devised based on the issue of microplastics in personal care products, which are a primary source of microplastics in marine environments. Given recent legislative action against personal care components such as microbeads, the development of a commercially viable non-aqueous rheology modifier was targeted as current bio-based offerings were sub-optimal in performance. A system comprising a highly branched vegetable oil-derived polymer was developed and optimised to this end, while additional applications and properties were investigated, including the ability of the vegetable oil-derived polymer to act as a re-bondable adhesive and its degradability via Aza-Michael reaction with a primary amine (Chapter 2).

Date of Award	27 Mar 2024
Original language	English
Awarding Institution	University of Bath
Supervisor	Matthew Davidson (Supervisor), Karen Edler (Supervisor) & Steven Brown (Supervisor)