Clay particles in suspension and at interfaces

Condensed Matter lunchtime seminar

Clay particles in suspension and at interfaces

  • Event time: 2:00pm
  • Event date: 9th October 2013
  • Speaker: Jeroen Van Duijneveldt (University of Bristol)
  • Location: Room 2511,

Event details

High aspect ratio colloidal particles (either rod-like or plate-like) may form either liquid crystal or gel structures at low concentration. They serve as viscosity modifiers in formulations and as fillers in polymer nanocomposites. We focus on natural clay particles, and use (polymer) surfactants to control particle interactions in either oil or water.

Montmorillonite clay can be delaminated into individual 1 nm thick platelets with very high aspect ratio (1:400) [1]. Adsorbing amine-based surfactants in water results in a shift of the sol / gel transition to a much higher clay concentration, compared to suspensions of bare clay particles. A nematic phase remains elusive however [2]. Modified clays also allow preparing oil-in-water Pickering emulsions [3]. When adsorbing polyethylenimine to the particles, such droplets could be cross-linked into microcapsules [4].

Sepiolite consists of rod-like particles. Surface modification results in suspensions which form a nematic phase in line with predictions for hard rods - however with the coexistence region broadened due to polydispersity [5]. Porous channels in the particles allow preparing dyed (dichroic) or fluorescent rods [6,7].

[1] E.S.H. Leach, A. Hopkinson, K. Franklin and J.S. van Duijneveldt, Langmuir, 21: 3821-3830, 2005. [2] Y. Cui, C.L. Pizzey and J.S. van Duijneveldt, Phil. Trans. R. Soc. A 371: 20120262, 2013. [3] Y. Cui, M. Threlfall, and J.S. van Duijneveldt, J. Colloid Interface Sci. 356: 665-671, 2011. [4] Y. Cui and J.S. van Duijneveldt, Langmuir 28, 1753-1757, 2012. [5] Z. X. Zhang and J.S. van Duijneveldt, Langmuir , 22: 63-66, 2006. [6] N. Yasarawan and J.S. van Duijneveldt, Langmuir, 24: 7184 - 7192, 2008. [7] N. Yasarawan and J.S. van Duijneveldt, Soft Matter, 6: 353-362, 2010.}, time={2:00pm

This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..

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