3D investigation on polystyrene colloidal crystals by floatage self-assembly with mixed solvent via synchrotron radiation x-ray phase-contrast computed tomography. (June 2017)

• Record Type: Journal Article
• Authors: Fu, Yanan; Xie, Honglan; Deng, Biao; Du, Guohao; Xiao, Tiqiao
• Is Part Of: Radiation physics and chemistry. Volume 135(2017)
• Page Start: 49
• Page End: 54
• Publication Date: 2017-06
• Subjects: Colloidal crystal -- Floatage self-assembly -- Mixed solvent -- Synchrotron radiation -- Computed tomography -- Phase-contrast; Radiation chemistry -- Periodicals; Radiometry -- Periodicals; Radiation -- Periodicals; Chimie sous rayonnement -- Périodiques; 539.2
• DOI: 10.1016/j.radphyschem.2017.02.050
• Languages: English
• ISSNs: 0969-806X

Abstract

Abstract: The floatage self-assembly method was introduced with mixed solvent as the medium of polystyrene sphere suspension to fabricate the colloidal crystal. The three dimensional (3D) void system of the colloidal crystal was noninvasively characterized by synchrotron radiation phase-contrast computed tomography, and the quantitative image analysis was implemented aiming to the polystyrene sphere colloidal crystal. Comparing with gravity sedimentation method, the three samples fabricated from floatage self-assembly with mixed solvents have the lowest porosity, and when ethylene glycol and water were mixed with ratio of 1:1, the lowest porosity of 27.49% could be achieved, that has been very close to the minimum porosity of ordered 3D monodisperse sphere array (26%). In single slices, the porosities and fractal dimension for the voids were calculated. The results showed that two factors would significantly influence the porosity of the whole colloidal crystal: the first deposited sphere layer's orderliness and the sedimentation speed of the spheres. The floatage self-assembly could induce a stable close-packing process, resulted from the powerful nucleation force-lateral capillary force coupled with the mixed solvent to regulate the floating upward speed for purpose of matching the assembly rate. Highlights: SR phase-contrast CT is introduced to view the 3D structure of colloidal crystal. Floatage self-assembly for colloidal crystal is introduced. Mixed solvent is involved to tune the rate of sedimentation of PS spheres. The first layer's orderliness and sedimentation speed of the spheres are important.