Towards stimuli-responsive polymers for rheological control
The aim of this work, sponsored by Lubrizol, was to develop polymers for potential use as novel viscosity modifiers for automotive oils. The broader scope was to build towards the incorporation of stimuli-responsive behaviour (temperature, shear, pH etc.), since there is currently no such technology on the market which does so. The Haddleton group has developed expertise in Cu(0)-mediated RDRP techniques, and so these were utilized throughout the thesis.

As a starting point, α,ω-functional lipophilic poly(butyl acrylates) were synthesized, which were then functionalized post-polymerization using thio-bromo substitution with a view to inducing associative thickening. During this investigation, a novel biphasic reaction scheme was noted, wherein the polymer was observed to phase separate from the solvent/catalyst mixture. Additionally, some previously unreported ligand effects were found. The incorporation of ureido-pyrimidinone hydrogen bonding motifs to lipophilic poly(acrylates) was also pursued, with the subsequent materials showing interesting rheological characteristics.

The biphasic Cu(0)-mediated RDRP system was then used to synthesize poly(lauryl) and (butyl acrylate) star polymers with exceptional degrees of control over the molecular weights and dispersity. These reactions were then successfully scaled up to produce enough materials to undergo some standard industrial tests, to assess their suitability as VMs.

Lastly, a collaborative side-project was also undertaken which moved away from generating oil-soluble polymers to examining the feasibility of grafting poly(NiPAM) brushes from water purification membranes using aqueous ‘SET-LRP’. This was shown to be possible, as demonstrated using a range of surface analysis techniques.