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 (<i>l</i>/<i>d</i> > 4) could be easily obtained

Azo Coupling Reaction Induced Macromolecular Self-Assembly in Aqueous Solution

This communication reported azo coupling reaction induced macromolecular self-assembly in aqueous solution. Diblock copolymer (PEG-<i>b</i>-PSNHBoc) consisting of a hydrophilic PEG block, and a hydrophobic N-Boc protected poly­(<i>p</i>-vinylaniline) block was synthesized by RAFT polymerization. Then double hydrophilic diblock copolymer (PEG-<i>b</i>-PSN₂⁺) composed of PEG and PS based macromolecular diazonium salts was prepared by the diazotization of PEG-<i>b</i>-PSNH₂, which was obtained by deprotection of PEG-<i>b</i>-PSNHBoc. As <i>N</i>,<i>N</i>-dimethylaniline was gradually added into the freshly prepared PEG-<i>b</i>-PSN₂⁺ aqueous solution, the azo coupling reaction between <i>N</i>,<i>N</i>-dimethylaniline and diazonium salts took place, which would lead to the generation of azobenzene pendants. Due to the poor solubility of azobenzene pendants in water, the formed hydrophobic polymeric chains aggregated to form the self-assembly colloidal particles. By incorporating a fluorescent group into the aniline, the aggregates formed through azo coupling reaction induced macromolecular self-assembly showed enzyme-triggered fluorescent behaviors

Synthesis and Characterization of Photoprocessable Lignin-Based Azo Polymer

Lignin-based azo polymer-bearing pseudo-stilbene-type azo chromophores have been synthesized by a post-azo coupling reaction between the modified alkali lignin and diazonium salts of 4-aminobenzoic acid in DMF with high yield. The polymer synthesized was characterized by using spectroscopic methods. Significant dichroism and surface relief patterns could be photoinscribed on the prepared azo polymer films by using appropriate laser beams. Self-assembly of the lignin-based polymer in selective solvents (THF/H₂O) can give uniform colloidal spheres, which can be elongated along the polarization direction of the irradiation light. This novel synthesized lignin-based azo polymer could potentially be used for applications such as reversible optical data storage, photoswitching, sensors, and other photo-driven devices, which provide a simple strategy for value-added utilization of lignin biomass resources