Development of a Novel, Mouldable and UV-Curable Polymer for use In Ostomy Care

Abstract

Ostomy sealants play a critical role in ostomy care, yet current state-of-the-art sealants are inadequate for many patients. In fact, 34% of ostomy patients experience leakage between the stoma and the ostomy bag, leading to skin irritation and potential infections. To address this issue, this project aims to design and synthesise an advanced ostomy sealant that is both mouldable by hand and UV curable. This allows it to conform precisely to the surface surrounding the stoma and be cured under UV light, creating a customised, patient-specific seal. Thus, this thesis reports on the synthesis of a novel, mouldable and photo-responsive polymer, capable of crosslinking upon irradiation with UV light, via the intermolecular [2+2] photocycloaddition of pendent crosslinkers.

Initially, the synthesis of poly(2-hydroxyethyl acrylate-ran-ethylfurfurylideneacetate acrylate) (P(HEA-ran-EFA)) copolymers was performed via reversible-addition fragmentation chain transfer (RAFT) polymerisation of 2-hydroxyethyl acrylate (HEA), followed by Steglich esterification with 3-(2-furyl) acrylic acid. The incorporation of pendent furyl acrylate crosslinkers facilitated effective [2+2] photocycloaddition reactions between polymer chains after 30 minutes of UV (315 nm - 400 nm) irradiation, as demonstrated by FTIR and GPC analysis. An ethylfurfurylideneacetate acrylate (EFA) molar composition of 15% within P(HEA-ran-EFA) was tentatively found to be suitable for effective crosslinking upon irradiation with UV light. However, upon purification (i.e., solvent removal) of the uncured polymer, P(HEA-ran-EFA) copolymers underwent a change in chemical composition, inferred from their change in solubility behaviour, complicating further study.

To replace EFA, the development of poly(2-hydroxyethyl acrylate-ran-cinnamoyl ethyl acrylate) (P(HEA-ran-CEA)) copolymers was investigated, synthesised by RAFT polymerisation of HEA, followed by Steglich esterification with cinnamic acid. This approach yielded a series of copolymers with varying degrees of functionality. Among these, P(HEA85-ran-CEA11) (12% crosslinker) exhibited optimal physical properties (i.e., mouldability by hand) in the uncured state, as determined by oscillatory rheology. Upon UV (100 nm - 280 nm) irradiation for 30 minutes, the polymer underwent successful intermolecular [2+2] photocycloadditions, confirmed by GPC and FTIR analysis. However, oscillatory rheology revealed that the polymer did cure effectively suggesting that an insufficient number of intermolecular chemical bonds were formed between polymer chains.

HEA was replaced with lauryl methacrylate (LMA), a dedicated soft monomer unit in the development of poly(cinnamoyl ethyl acrylate-ran-lauryl methacrylate) (P(CEA-ran-LMA)) copolymers. These copolymers were synthesised by RAFT copolymerisation of HEA and LMA, followed by Steglich esterification with cinnamic acid. This method produced a series of copolymers, among which P(CEA77-ran-LMA45) (63% crosslinker) displayed physical properties comparable to P(HEA85-ran-CEA11) (12% crosslinker) in its uncured state, but with increased crosslinker functionality. Upon UV (100 nm - 280 nm) irradiation for 30 minutes, the polymer underwent subtle curing, while extending the irradiation to 24 hours yielded more optimal physical properties in the cured state, as determined by oscillatory rheology, the material transitioned from a mouldable to non-mouldable but flexible material - appropriate properties for use an ostomy sealant.

Date of Award	Oct 2024
Original language	English
Awarding Institution	Aston University
Supervisor	Paul Topham (Supervisor) & Anisa Mahomed (Supervisor)