title: Fast dynamics and relaxation of colloidal drops during the drying process using multispeckle diffusing wave spectroscopy.
abstract: The fast dynamics generated by the Brownian motion of particles in colloidal drops, and the related relaxation during drying, which play key roles in suspension systems, were investigated incorporating multispeckle diffusing wave spectroscopy (MSDWS). MSDWS equipment was implemented to analyze the relaxation properties of suspensions under a nonergodic and nonstationary drying process, which cannot be elucidated by conventional light scattering methods, such as dynamic light scattering and diffusing wave spectroscopy. Rapid particle movement can be identified by the characteristic relaxation time, which is closely related to the Brownian motion due to thermal fluctuations of the particles. In the compacting stage of the drying process, the characteristic relaxation time increased gradually with the drying time because the particles in the colloidal drop were constrained by themselves. Moreover, variations of the initial concentration and particle size considerably affected the complete drying time and characteristic relaxation time, producing a shorter relaxation time for a low concentrated suspension with small particles.
authors.affiliation: Department of Chemical and Biological Engineering, Korea University, Seoul, Korea.
authors.forename: Jeong Yong
authors.initials: JY
authors.lastname: Lee
authors.forename: Ji Won
authors.initials: JW
authors.lastname: Hwang
authors.forename: Hyun Wook
authors.initials: HW
authors.lastname: Jung
authors.forename: Sung Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Seong Jae
authors.initials: SJ
authors.lastname: Lee
authors.forename: Kisun
authors.initials: K
authors.lastname: Yoon
authors.forename: David A
authors.initials: DA
authors.lastname: Weitz
mesh_terms: D003102:Colloids / Q000737:chemistry*; D003890:Desiccation; D004058:Diffusion; D057446:Hydrodynamics; D008027:Light; D010316:Particle Size; D012542:Scattering, Radiation; D013057:Spectrum Analysis / Q000295:instrumentation; D013499:Surface Properties
chemical_list: D003102:Colloids