Surface active microgels: a step towards soft stabilisers

Microgels are soft particles composed of cross-linked networks of polymers. A unique property of microgels is their ability to swell when dispersed in specific solvents. The size of microgels vary from several micrometers (‘swollen’) down to nanometers (‘unswollen’). ‘Unswollen’ microgels bear similarities to hard colloids however, when ‘swollen’ they act as soft particles. The rheology of microgel suspensions can be tuned by causing microgels to swell or de-swell. This ability to manipulate rheology of suspensions has led to microgels being abundant in a number of industrial applications such as food, pharmaceuticals and cosmetics [1]

Recent research has been dedicated to making a range of microgel-forming polymers in order to create responsive multifunctional microgels. Using customised polymer building blocks microgels can be made to react to different stimuli such as temperature or pH. Additionally, microgels can be modified to become surface active, allowing them to be used as emulsifiers. The combination of microgels rheology-modifying and emulsifying abilities makes them ideal candidates for designing emulsions with tuneable stability [2]. 

I study a commercially available microgel system composed of a polymer called Sepimax Zen, an amphiphilic block copolymer. In this talk I will discuss the bulk rheology of Sepimax Zen microgels and how they compare to other thickening agents. Furthermore, I will discuss my more recent structural measurements using DDM and tensiometry. Finally, I will discuss future experiments to be done in order establish a framework for designing emulsions using surface active microgels. 

[1] Fernandez-Nieves, Alberto, et al., eds. Microgel suspensions: fundamentals and applications. John Wiley & Sons, 2011.

[2] Deshmukh, Omkar S., et al. "Hard and soft colloids at fluid interfaces: Adsorption, interactions, assembly & rheology." Advances in colloid and interface science 222 (2015): 215-227.