A Research of Stereo-Selective Synthesis of Silica-based Amphiphilic Janus Particles

Because Janus particles with specific asymmetric nanostructures can be fixed in the oil phase or water respectively, they are more suitable for Pickering emulsion stability. Furthermore, the complete separation of hydrophobic and hydrophobic regions makes adjusting the hydrophobic/hydrophobic region ratio possible by changing the volume ratio. In this study, the preparations of three asymmetric silicon-based amphiphilic Janus nanoparticles are introduced. The methods used are consecutive immobilization, seed emulsion polymerization, and selective encapsulation, respectively. Complete compartmentalization of hydrophilic and hydrophobic domains was realized by anchoring silica with nucleation site, seed emulsion polymerization, or surface charge repulsion. In addition, these nanoparticles can be easily functionalized, bringing new research opportunities to applications in catalysis, adsorption, separation and biomedicine.

Controlled-release urea encapsulated by ethyl cellulose/butyl acrylate/vinyl acetate hybrid latex

Fertilizer encapsulation through polymer membranes can reduce fertilizer losses and minimize environmental pollution. In this paper, an emulsion of ethyl cellulose (EC)/vinyl acetate (VAc)/butyl acrylate (BA) was successfully prepared by pre-emulsified semi-continuous seed emulsion polymerization. EC/BA/VAc films showed biodegradability. The influence of the EC content on the properties of EC/BA/VAc films was also investigated by DSC, a water absorbency analysis, etc. Controlled-release urea encapsulated by EC/BA/VAc latex was prepared in a film coating machine and conformed to the standards for slow-release fertilizers of the Committee of European Normalization. The release of urea from controlled-release urea encapsulated by EC/BA/VAc latex containing 0%, 5%, 10%, and 15% EC was 75.1%, 65.8%, 70.1% and 84.1%, respectively, after 42 days, and controlled-release urea encapsulated by EC/BA/VAc latex (5% EC) had the best controlled-release ability. Therefore, controlled-release urea encapsulated by EC/BA/VAc latex has many potential applications in agricultural industry.

Preparation of morphology-controllable PGMA-DVB microspheres by introducing Span 80 into seed emulsion polymerization

The obtained PGMA-DVB microspheres showed a variety of morphologies by adjusting the amount of Span 80 in the seeded emulsion polymerization.

The Synthesis and Properties of Emulsion Copolymerization of Styrene with N-Substituted Phenyl Maleimide

The synthesis and characterization of copolymer emulsions of styrene with two types of N-substituted phenyl maleimide (N-p-Methyl–MPhMI and N-m-Methyl–MPhMI) were investigated and researched in this thesis, by varying the mole fraction of N-substituted phenyl maleimide and using a seed emulsion polymerization process. The emulsion was steady with high yield, low intrinsic viscosity, and high solid content (40%). In this thesis, we studied that the substituted position on the benzene ring of the N - substituted phenyl maleimide has significant influence on emulsion properties and thermal properties of copolymer emulsion copolymer. The result shows that: the polarity of N-p-MPhMI is higher than N-m-MPhMI, which can significantly improve the yield, and reduces the emulsion gel rate. N-p-MPhMI is more electronegative than N-m-MPhMI, and N-p-MPhMI-St copolymer emulsion has high zero shear viscosity and low surface tension than N-m-MPhMI-St. And N-m-MPhMI-St copolymer emulsion decreased the viscosity of Pst homopolymer emulsion. However, N-p-MPhMI-St copolymer emulsion rheology curve changes into pseudoplastic fluid. The addition of the N-substituted phenyl maleimide can improve the heat resistance of polystyrene, and N-p-methylphenyl maleimide with styrene copolymer can increase the glass transition temperature of copolymer more remarkably than copolymer N- m-tolylmaleimide with styrene can do.

Responsive P(NIPAM-co-AA) Particle-Functionalized Magnetic Microspheres

Functionalized magnetic microspheres were prepared by anchoring cross-linked core–shell poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAM-co-AA)) nanoparticles onto silica-coated magnetic microspheres (Fe3O4@SiO2). First, the smaller polystyrene/P(NIPAM-co-AA) core–shell nanoparticles were synthesized through seed emulsion polymerization and adhered to the surface of amino-modified Fe3O4@SiO2 micorspheres, which were made using the modified Stöber method through electrostatic interaction under appropriate preparation conditions. An amidation reaction between the carboxylic and amino groups on the respective surfaces was then catalyzed. Finally, the novel architecture magnetic microspheres with multiresponsive functionalities were obtained, and their polymerization conditions, environmental sensitivity, and magnetic properties were discussed and optimized. The superparamagnetism and temperature/pH dual responsivity and excellent dispersibility of the P(NIPAM-co-AA) functionalized magnetic microspheres provide them with high potential to be used in the fields of controlled drug delivery, bioseparation, and catalysis.