Hongjun Dai

Multi-membrane hydrogel fabricated by facile dynamic self-assembly

Multi-membrane hydrogels are newly promising carriers in biomedical fields. We fabricate alginate-based onion-like multi-membrane hydrogels starting from a template gel-core to shells through a dynamic self-assembly method, and investigate the influence of various factors on the formation of the complex system in detail. By precisely controlling the process of preparation, multi-layered hydrogels of different shapes either with or without defined internal space between separated layers can be prepared. And a pulse-like delivery of macromolecule has been achieved by this architecture.

Facile preparation of poly(ethyl α-cyanoacrylate) superhydrophobic and gradient wetting surfaces

Hollow microspheres of poly(ethyl alpha-cyanoacrylate) were prepared via vapor phase polymerization using micro-waterdroplets as template and initiator. Depending on the ratio of the shell thickness to the radius, the hollow microspheres would crimple to form either microballoons or microcups during drying. These two types of microparticles were used as building blocks to construct surfaces with diverse wettability. The microballoons linked up to form a porous-netlike surface which was rough enough to render the surface superhydrophobic, while the microcups-built surface showed less hydrophobicity. In addition, surfaces consisting of both microparticles with gradual decrease of roughness along the length direction were obtained, which presented gradient wetting property varied from superhydrophobic to hydrophobic. The as-formed superhydrophobic or gradient wetting surfaces may find potential applications in biomedical field because of the biocompatibility of poly(ethyl alpha-cyanoacrylate).

Optical investigation of diffusion of levofloxacin mesylate in agarose hydrogel

Real-time electronic speckle pattern interferometry method has been applied to study the diffusion behavior of levofloxacin mesylate (MSALVFX) in agarose hydrogel. The results show that the diffusivity of solute decreases with the increase of concentration of agarose and adapts to Kohlrauschs law. Furthermore, Amsdens model, based on the retardance effect associated with polymer chain flexibility, was employed to simulate the diffusion behavior. The consistent results suggest that the retardance effect dominates the diffusion process of MSALFVX in hydrogel; moreover, polymer chain flexibility greatly affects drug transport within the polymer matrix.

A Versatile Coating Approach to Fabricate Superwetting Membranes for Separation of Water-in-Oil Emulsions

Separation of oil/water mixtures, especially for the emulsified oil/water mixtures, is important because of the frequent occurrence of oil spill accidents. Utilizing superwetting porous membrane has become a promising approach to separate either surfactant-free or surfactant-stabilized emulsions. Herein we report a facile and versatile strategy for preparing hydrophobic/under-oil superhydrophobic membranes by coating the skeletons of the membranes with the poly[(3,3,3-trifluoropropyl)methylsiloxane] (PTFPMS) nanoparticles. The obtained membranes could be used to separate various waterin- oil emulsions with high flux and separation efficiency. In addition, owning to the outstanding resistance of PTFPMS to the most organic solvents or oils, the modified membranes exhibited the excellent reusability and the antifouling properties that were critical in the practical applications. Many commercially available membranes can be modified by such a simple method.