Polymer-surfactant complexes in emulsion systems: responsive coatings and function

Project Leader: Ray Dagastine
Primary Contact: Ray Dagastine (rrd@unimelb.edu.au)
Keywords: Complex Fluids; Drops and Bubbles; nanoengineered materials; protein assembly; Soft Matter
Disciplines: Chemical & Biomolecular Engineering
Domains: Convergence of engineering and IT with the life sciences
Research Centre: Particulate Fluids Processing Centre (PFPC)

Polymer Surfactant (PS) complexes are used to control particle suspension stability and surface properties such as wettability and adhesion for applications in areas such as personal care products, coatings, herbicides, paper-making, oil recovery, and pharmaceutical suspensions.  When PS complexes coat colloid particles (capsules, drops, solid particles), they can act as responsive coatings that can both stabilize or flocculate these suspensions to change bulk properties of a formulated products such as shelf life, rheological properties and textures, particle adhesion, etc..  The PS complex tendency to phase separate in solution leads to a number of novel properties and functions but also presents challenges in quantifying the underlying fundamental mechanisms that control bulk property behavior. Developing structure-function relationships between the molecular scale of polymer-surfactant complexes adsorbed onto colloidal particles to macroscopic solution conditions is crucial in using these systems as means to manipulate and control delivery, stability or texture of the formulated systems.


This is an area of extensive academic research over the last 40 years, yet there are still many gaps in our understanding linking the molecular structure and composition of polymers and surfactant to their associative behavior in solution and their ultimate function or benefit in a formulation.  This is in part attributed to the complexity of a formulation and the degrees of freedom on a molecular scale in even the simplest model system.  In addition, the discoveries in the literature are often more qualitative in nature where it is still challenging to use this understanding to quantifiably predict changes in structure or function from changes in surfactant or polymer composition.


Within the last ten years, new experimental methods, such as using atomic force microscopy have become developed to measure the interactions of emulsion drops with hydrophobic or hydrophilic surfaces allow for the opportunities to make more direct connections between structure of PS complexes over a wider range of conditions in less time.


The main aim of this project is to develop structure-function relationships between the molecular scale of polymer-surfactant complexes adsorbed onto surfaces to macroscopic scale behaviors using a suite of advanced colloid and surface science tools based around atomic force microscopy.  This study will lead to an enhanced understanding of PS complexes used our everyday lives with direct connections to industrial projects. 

Further information: http://www.chemeng.unimelb.edu.au/dagastine/index.html