Seminar. Vince Craig

Abstract below

Vincent S. J. Craig

Department of Materials Physics, The Research School of Physics, Australian National University

Canberra, Australia

When Chemistry and Physics both matter: Understanding and quantifying the influence of the type of electrolytes (beyond valency) on solutions and soft matter systems.

Salt solutions are ubiquitous, essential to life as we know it and industrially important, yet poorly understood due to their complexity. Their complexity is largely due to both long range electrostatic interactions and specific ion effects – where the identity of the ion is important not just the valency of the ion.

Specific ion effects have been known since the late 1800’s and are often characterised as Hofmeister effects.  In this presentation I will describe my specific ion effect journey from bubble coalescence studies, through studies of non-aqueous systems1 into studies of highly concentrated electrolytes2-3. This is a journey from complete ignorance to the emergence of a quantitative understanding of the Hofmeister series4.

I will also describe some of the challenges in going beyond the Hofmeister paradigm, particularly in highly concentrated electrolytes, in which ion-ion correlations give rise to re-emergent long range electrostatic interactions5.

 

  1. Mazzini, V.; Liu, G.; Craig, V. S., Probing the Hofmeister Series Beyond Water: Specific-Ion Effects in Non-Aqueous Solvents. J. Chem. Phys. 2018, 148.
  2. Liu, G.; Parsons, D.; Craig, V. S. J., Re-Entrant Swelling and Redissolution of Polyelectrolytes Arises from an Increased Electrostatic Decay Length at High Salt Concentrations. J. Colloid Interface Sci. 2020, 579, 369-378.
  3. Yuan, H.; Deng, W.; Zhu, X.; Liu, G.; Craig, V. S. J., Colloidal Systems in Concentrated Electrolyte Solutions Exhibit Re-Entrant Long-Range Electrostatic Interactions Due to Underscreening. Langmuir 2022, 38, 6164-6173.
  4. Gregory, K. P.; Wanless, E. J.; Webber, G. B.; Craig, V. S.; Page, A. J., The Electrostatic Origins of Specific Ion Effects: Quantifying the Hofmeister Series for Anions. Chemical Science 2021, 12, 15007-15015.
  5. Lee, A. A.; Perez-Martinez, C. S.; Smith, A. M.; Perkin, S., Scaling Analysis of the Screening Length in Concentrated Electrolytes. Phys. Rev. Lett. 2017, 119, 026002.

Figure 4 taken from 10