BCAT-5 Three-Phase Dynamics Simon Fraser University Art Bailey, Barbara Frisken, Juan Sabin

Three-phase Separation Dynamics One sentence definition of SFU’s BCAT-5 Experiment The study of phase separation dynamics when gas, solid and liquid phases of a colloidal suspension coexist.

Outline States of Matter / Phase Transitions Colloids States of Colloidal Matter Colloid Experiments in Space BCAT-5

“Traditional” States of Matter

Differences between states

Atomic Differences

Phase Transitions Transition from one state to another Boiling Freezing Sublimation Demixing Mixtures Alloys Polymer blends What are the “mechanisms” of these phase transitions? Tougher problems to study because non-equilibrium problems.

Phase Transitions that Matter Vinaigrette Metal / Plastic Alloys Fuels

Phase Separation in 3-Phase Coexistence 2-phase Separation studied for more than 50 years. 3-phase Separation Crystals, Liquid and Gas all forming out of a homogenized mixture Applications Properties of polyolefin blended plastics Mechanical properties determined by the separation / crystallization. Polypropylene and Polyethylene Fire retardants, packing materials Protein Crystallization Tetragonal Lyzozyme crystals lysozyme.co.uk/crystallization.php

What’s a Colloid? Colloids – Particles of size 1 nm – 10 microns. Larger than atomic/molecular size, smaller than ‘macroscopic’.

Why Colloids? Lots of technological examples Colloids model atomic and molecular systems but are simpler to study

Hard Sphere Colloids PMMA colloid with PHSA coating

Phases of Colloids Hard Spheres – like billiard balls

Colloid-Polymer Mixtures Depletion Attration – Entropy causes an “effective” attractive interaction.

Polymers Increase Phase Behaviour PCS BCAT-3,4-CP BCAT-5 Experiments 3 Samples in 3-phase region.

Looking Forward http://www.ph.ed.ac.uk/~wckp/#PhysicsResearch, W.C.K. Poon

Colloids in Space PHaSE CDOT CDOT-2 PCS Coexistence Fully Crystalline

Why Colloids in Space Sedimentation Particle a h Ball bearing 1 mm 10-20 m Air molecule 1 nm 103 m Polystyrene spheres in water 2 mm particle size, a gravitational height, h if h<a,gravity is important Gravity causes colloids to fall to the bottom of the sample cell!

Colloid-Polymer Phase Separation

BCAT-5 Sample Tray The BCAT-5 Slow Growth Sample Module is 12.7cm x 26.7cm x 3.2cm and contains 10 (2.3cc) sample cuvettes.

BCAT-5 Apparatus

Phase Separation (BCAT-3) Colloid rich phase Colloid poor phase Measure the size of the regions to determine the rate of phase growth. Courtesy of D.Weitz, P. Lu, Harvard University

SFU on BCAT-5

Looking Forward http://www.ph.ed.ac.uk/~wckp/#PhysicsResearch, W.C.K. Poon

The End Questions?

Soft Matter Physics “Particles” interact with energies comparable to thermal energies. Entropy Coulombic forces (ie. Charge) No (well…. At least not much) quantum mechanics.

Interesting Properties Gels Shear thinning or shear thickening

“Soft” Matter