Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.629237
Title: Non-equilibrium polymeric complex fluids
Author: Willmer, D.
Awarding Body: Nottingham Trent University
Current Institution: Nottingham Trent University
Date of Award: 2011
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Abstract:
Complex fluids are commercially- and industrially-important materials which exhibit ordering on scales much larger than atomic. Their usage is typically in non-equilibrium conditions, however traditional methods for measuring rheology are not appropriate for measuring samples with gradients present, such as temperature and concentration. In this work a safe and easy to use optical tweezer (OT) apparatus has been developed in order to facilitate the investigation of various systems during dilution or drying. In contrast to other OT setups, this equipment is safe to use without laser goggles or interlocked rooms, yet still allows full access to the microscope. Proof-of-concept experiments are performed on aqueous poly (ethylene oxide) (PEO) solutions to demonstrate the changes in viscosity and concentration over time, and the OT is then used in a rheological investigation into a commercially-relevant wormlike micelle (WLM) system, in conjunction with Diffusing Wave Spectroscopy (DWS) and traditional bulk rheology. It is shown for the first time that equimolar (eM) SDS:CAPB WLM samples can be considered ‘model’ systems, and form close approximations of Maxwellian systems on the addition of extra salt or surfactant above 0.1eM. The effect of an uncharged polymer (PEO 4M MW) on this WLM network structure was subsequently investigated; its effects are consistent with current theories of polymer-surfactant interactions. The effect of a conditioning polyelectrolyte on the network structure was also studied; its effect was highly dependent on surfactant and electrolyte concentration, but hinted at the previously unreported behaviour of a polyelectrolyte initiating micellar branching. A precursor investigation into evaporation of sessile droplets of aqueous PEO solutions is presented last, reporting a previously unseen droplet evaporation regime in which the solid deposits grow to nearly twice their starting height. This research concludes that the growth phenomena is due to the unusual solvation mechanism of PEO, and a predictive theory is presented in support of this.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.629237  DOI: Not available
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