Morphological instabilities in drying colloids

by Pree-cha Kiatkirakajorn
Doctoral thesis
Date of Examination:2018-09-10
Date of issue:2018-10-15
Advisor:Dr. Lucas Goehring
Referee:Dr. Lucas Goehring
Referee:Prof. Dr. Marcus Müller
Persistent Address: http://dx.doi.org/10.53846/goediss-7094

 

 

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Abstract

English

The crystallization of hard sphere colloidal dispersions show a variation of phase behaviours, as the volume fraction of colloidal dispersions increases, particles transform from a liquid to a crystal state, which two simple structures can be found close-packed and body-centred cubic crystals depending on the range of interaction forces. Here, we show a result of Small-Angle X-ray Scattering experiment of monomodal-sized colloidal dispersions. The phase diagram, structure factors and crystal peaks were analysed by the scattering pattern of X-ray. We found coexistences of complex crystal structures (two BCC structures and Laves AB2) for the small particle size, and complex crystal structures (BCC and FCC) for the larger particle size which is suggested by a fractionation among the particles. We further complete our suggestion through the numerical results which are able to explain how the fractionation occurs and how the particles distribute among them. Moreover, we investigated instabilities, shear banding and guiding cracks, which are a result of the structural anisotropy in the drying film.
Keywords: colloids; drying colloids; instabilities; colloidal dispersions; crystallization; SAXS; phase diagram; shear band; cracks
 
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