We sheared a colloidal glass, and found that the resulting state of matter shows several striking similarities to that of a supercooled colloidal liquid: i) an MSD that is linear in time at long times, ii) strongly cooperative dynamics, iii ) heterogeneous dynamics for times shorter than the diffusion time but homogeneous dynamics for longer times. In contrast to the situation in a supercooled liquid, however, we find strongly cooperative microscopic dynamics also in the dynamically homogeneous regime for the shear-melted glass. This is a direct effect of the high packing fraction characterizing the glassy state. The highly driven dynamics in the shear-melted glass can occur only by cooperative rearrangements involving several neighbors. Thus, shear-melting albeit similar to the volume fraction controlled glass-liquid transition, leads to an entirely different state of matter.
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•Dynamics of Shear Melted Colloidal Glasses
We utilized chemically inert glass capillaries based microfluidic device to generate monodisperse emulsions, colloids, or liposomes. This technique can be used to encapsulation of drug, cell or active biomaterials in lipid vesicle or bio gels for drug delivery and bioreactor applications.
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•Microfluidics
We synthesized fluorescently-labeled polymer particles in a density- and index- matched organic solvent. These particles can be used to study model atomic systems.
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•Colloidal particle synthesis
We have produced monodisperse liquid crystal elastomer (LCE) colloidal particles. The LCE particles are composed of siloxane polymer backbone, mesogen on the side and crosslinkers. LCE materials are provided by the New Liquid Crystal Materials Facility (NLCMF).
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•Colloidal Liquid Crystal Elastomers
We are investigating the effects of size, shape and surface modification of magnetic nanoparticles (MNPs) that can be used in biomedical applications such as magnetic resonance imaging (MRI), tissue engineering, hyperthermia, and gene and drug delivery.
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•Modification of magnetic nanoparticles for Biomedical Applications
We have mixed nematic liquid crystal with 10v% colloidal particles. We find that the composite self-assembled to a 3D hierarchical “FERN” structure. We are exploring various conditions such as cooling rates, particle sizes and anchoring conditions to find the mechanism of the self-assembly of particles in anisotropic fluid.
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•Colloidal Liquid Crystal Composites
* This project is supported by the NSF (OISE-1004228).
The objective of this project is to explore novel strategies for the synthesis of mesoporous silica microencapsulation for biomedical applications such as drug delivery and controlled release. They have been used for wide range of applications, such as drug delivery systems, molecular and cellular encapsulation, and microreactor.
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•Microbottles
Our study has shown that a surface modification process with PEG produces non-bleaching photoluminescent (PL) biocompaticle coatings on the magnetic nanoparticles without any addition of fluorophores, such as quantum dots or fluorescent dyes. Using this simple method, it is possible to produce dual-mode bio-imaging (fluorescence and magnetic resonance imaging) contrast agents. In-vivo tests on mice with the PL-MNPs show that PL-MNPs have excellent biocompatibility. In addition, even without the magnetic nanoparticles, PL-PEGs can be produced by a simple process. The remarkable non-photobleaching property of the PL-PEGs was confirmed by long time light exposure.
As a low-cost, bio-safe, non-bleaching alternative of conventional fluorophores, the applications of the PL-PEGs and PL-MNPs cover a wide range from biomedical diagnostics and therapeutics to industrial materials.
We study 2D colloids in solid and hexatic phases that show seemingly Fickian but strongly heterogeneous dynamics. But dynamics is still heterogeneous significantly with non-Gaussian Gs(r, t) and several peaks taht may be related to dynamics clusters of discs with discretized mobility.
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•Dynamics of 2D colloidal system
