Self-assembly of novel catechol-containing copolymers in nonpolar solvent

Abstract

Functionalised polymers are widespread in a variety of industries for a variety of purposes ranging from engine oil additives to anti-fouling coatings to medical wound dressings. The development of novel polymers for uses in nonpolar solvent remains relevant to multiple challenges faced by industry such as the reduction of carbon dioxide emissions through lubrication, the development of improved anti-wear additives to prolong component lifetime, and the development of oil additives for use in future transport such as electric cars. The catechol group has been identified over the last few decades as a highly promising candidate for use in polymers as an anchoring group, owing to its powerful bio-inspired adhesion and surprisingly versatility in binding mode and adhesion to a wide range of different surfaces. Despite the large number of studies that have been carried out on both functionalised polymers for use in oil, and on catechol-containing polymers in aqueous environments, these two areas have not yet been combined to produce a large literature base on catechol-containing copolymers in nonpolar solvent. In this work, this area is explored through the study of the self-assembly of a series of catechol (CAT)-containing copolymers in n-dodecane, a model oil. In this work, small-angle neutron scattering (SANS) was used to study the self-assembly of these CAT-containing copolymers at different concentrations and temperatures, where it was found that the self-assembly of these copolymers depended very sensitively on the number of CAT moieties present along the polymer chain, as well as their ability to access one another without steric hindrance, providing evidence that hydrogen-bonding is the main driving force behind the self-assembly of these polymers in oil. Water-in-oil emulsions were then formed using solutions of the CAT-containing polymers, providing further evidence for the critical importance of H-bonding for their self-assembly. Finally, the self-assembly of these CAT-containing copolymers was examined at the interface using X-ray reflectivity (XRR) and adsorption isotherms, demonstrating that all polymers including a non-CAT-containing homopolymer NC-HP adsorbed onto both silica and iron (III) oxide, with the higher-CAT-content diblock copolymer HC-DB having both the greatest energy of adsorption and forming the thickest adsorbed layers. These results demonstrate the suitability of CAT as a group to be included in polymers intended for applications in oil, and may act as both a versatile anchoring group and to drive highly-tuneable self-assembly. This may then be used as a starting point for the design of further CAT-containing copolymers for various uses in oil, and for further studies into the sensitivity of different polymer architectures such as multiblock, star, and branched copolymers to CAT.

Date of Award	9 Dec 2025
Original language	English
Awarding Institution	University of Bristol
Sponsors	Infineum UK Ltd
Supervisor	Wuge H Briscoe (Supervisor) & Peter J Dowding (Supervisor)