CaIFF Webinar: Catherine Whitby

Manipulating shape transitions in light and temperature-sensitive reconfigurable Pickering emulsions

Abstract

S. Chourasiaa,b and C. P. Whitbya,b,c 
 a School of Food Technology and Natural Sciences, Massey University, Palmerton North, 4410, New Zealand
b The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, 6140, New Zealand
c Riddet Institute, Palmerston North, New Zealand 

*c.p.whitby@massey.ac.nz

 
Reconfigurable emulsion systems respond to external stimuli, reconfiguring drop shapes and structures in response to changes in environmental conditions. Complex, multicompartment surfactant-stabilised emulsions that reconfigure when triggered by stimuli such as temperature, pH, magnetic fields and light have been fabricated.1–3 They offer the ability to manipulate emulsion stability, microstructure and function on demand. The impact of remains an open question. 
 
In this seminar, I will describe some of our work investigating the impact of particles at the interfaces in the emulsions on the shape transitions in reconfigurable systems. We formulated light-responsive oil-in-oil-in-water double emulsions stabilised by surfactants and particles. Hydrocarbon and fluorocarbon oils were used to form droplets with Janus configurations.

The oil-water interfaces in the emulsions were stabilised by mixtures of fluorocarbon and photo-responsive surfactants. The photo-responsive surfactant contained an azobenzene moiety that underwent photo-isomerization between cis and trans forms. Irradiating the emulsions with UV light caused changes in the droplet configuration which could be reversed on irradiating with blue light.

Our research extends earlier findings on similar systems4 by using optical and confocal fluorescence microscopy to visualise the changes in the droplet morphology caused by systematically varying the emulsion composition. A key finding is the extent to which the particle concentration and location in the emulsions alters the droplet reconfiguration.

References 

  1. Zarzar, L. D., Sresht, V., Sletten, E. M., Kalow, J. A., Blankschtein, D., & Swager, T. M. Nature 2015 518 520-524.
  2. Ge, X. H., Geng, Y. H., Zhang, Q. C., Shao, M., Chen, J., Luo, G. S., & Xu, J. H. Scientific Reports 2017 7, 42738.
  3. Pavlovic, M., Antonietti, M., Schmidt, B. V., & Zeininger, L. Journal of Colloid and Interface Science 2020 575,
    88-95.
  4. Cheon, S. I., Batista Capaverde Silva, L., Ditzler, R., & Zarzar, L. D. Langmuir 2020 36, 7083-7090.

Speaker

Catherine Whitby, Massey University

 

Registration link to Zoom Event

https://ucph-ku.zoom.us/webinar/register/WN_dKOX_lg8QX6qjSeRb4wnkw