Yuqi Zhou

Fast Photoinduced Large Deformation of Colloidal Spheres from a Novel 4-arm Azobenzene Compound

A novel 4-arm shaped amphiphilic azobenzene compound was synthesized. The tetraphenylethylene (TPE) core precursor was prepared and further modified by azo coupling reaction at the four peripheral groups. Colloidal spheres could be directly prepared by self-assembly of the prepared amphiphilic azobenzene compound in selective solvents (THF/H2O), which were characterized by using transmission electron microscopy. The colloid diameters could be controlled by adjusting the initial compound concentration and water-adding rate in the preparation processes. By irradiation with visible linearly polarized LED light (450 nm), fast photoinduced deformation of the colloidal spheres along the polarization direction was observed. A very large deformation degree (l/d > 4) could be easily obtained.

Synthesis of Y-shaped amphiphilic copolymers by macromolecular azo coupling reaction

The synthesis of AB2 Y-shaped amphiphilic block copolymers by macromolecular azo coupling reaction is reported. The hydrophobic block with the functional group at the end of the polymeric chain was prepared by controlled radical polymerization methods such as RAFT and ATRP. The hydrophilic block with diazonium salt group was obtained by the diazotization of V-shaped aniline-functionalized PEG. Then Y-shaped block copolymers were easily prepared through macromolecular azo coupling reactions between the abovementioned two polymeric blocks. The results of experiments showed that the position of the functional group suitable for azo coupling reaction in the polymeric chain has considerable effect on the efficiency of macromolecular azo coupling reaction. It was easier for the macromolecular diazonium salts to attack the functional groups when they were at the end of the macromolecular chains instead of in the middle. The self-assembly properties of the obtained Y-shaped amphiphilic block copolymers were also studied. Colloidal spheres were prepared by gradual hydrophobic aggregation of the polymeric chains in a THF–H2O dispersion medium.

An air-breathing silicon-based micro direct methanol fuel cell with a capillary-based water drawn out structure

This paper presents a capillary-based cathode structure for air-breathing micro direct methanol fuel cell (μDMFC). An array of capillaries with hydrophilic surface is designed on the ribs of cathode window to draw out excessive water from the cathode. Microfabrication techniques, including double-side lithography and ICP, are used to fabricate anode and cathode plates of the μDMFC on the same silicon wafer simultaneously. Both μDMFCs, one with capillary-based water drawn out structure and the regular one without, are assembled and characterized. Experimental results show that the μDMFC achieves a power density of 2.35mW/cm2, 10% larger than that of the regular one, of which the power density is about 2.1mW/cm2. The capillary-based water drawn out structure on the cathode draws water out in evidence.

Photodeformable microspheres from an azo molecule containing a 1,4,3,6-dianhydrosorbitol core and cinnamate peripheral groups

Microspheres formed from an azo molecule containing a 1,4,3,6-dianhydrosorbitol core and cinnamate peripheral groups are fabricated by the solvent-induced self-assembly in an aqueous dispersion. The effect of the initial concentration on the microsphere formation is elucidated by investigations with light scattering and TEM observation. Photoinduced deformation along the light polarization direction is demonstrated for the microspheres in the solid state upon the irradiation with a linearly polarized light. The deformation occurs at a much faster rate compared with that of azo polymer microspheres under the same light irradiation condition.

A novel assembly method for micro direct methanol fuel cells using multi-layer bonding technique

This paper reports a novel assembly method for micro direct methanol fuel cells (μDMFC) by using multi-layer bonding technique. The new approach shows exceeding merit on maneuverability and reliability, and is beneficial to decreasing the internal resistance of the μDMFC. The prototype generates a high power density of 20.29mW/cm2. Moreover, this work presents a promising strategy for the assembly of μDMFC stacks and other microfluidic devices with laminated structures.