Preparation Of Polymers Nanodispersion By High-gravity Technology For Multifunctional Applications

Polymer nanodispersion,the aqueous dispersoid of polymer nanoparticles,is an important polymer nano-material.The application range of polymer nanoparticles has expanded rapidly,and played a pivotal role in a wide range of fields during the last decades.The synthesis process of polymer nanoparticles prepared by polymerization of monomers is one of the most promising methods for preparing polymer nanoparticles with desired properties for a particular application.The choice of method depends on a number of factors,such as,particle size,particle size distribution,area of application and so on.The miniemulsion polymerization and emulsion polymerization techniques are the major techniques currently in use.The miniemulsion polymerization process allows the formation of complex structured polymer nanoparticles and the encapsulation of various materials into a polymer shell.Miniemulsion polymerization seems to be the perfect technique to synthesize complex nanomaterials.And it has made some achievements in the industrial production,but it also faces many challenges.In this topic,we couple the rotating packed bed reactor with the miniemulsion polymerization reaction,study the characteristics of the reaction process and design and apply the high-gravity miniemulsion polymerization technology to improve the process.The first part of the research is the theoretical research of in situ visualization of emulsion Polymerization and miniemulsion polymerization.We used the laser scanning confocal microscopy to visualize the polymerization processes via real-time AIEgens fluorescence imaging.Than we designed a high-gravity miniemulsion polymerization process based on the results of the theoretical research.The new polymerization process was used for the radical polymerization,radical copolymerization and stepwise polymerization.The polystyrene nanoparticles,polymethyl methacrylate-co-methacrylate nanoparticles,polymethyl methacrylate-co-butyl acrylate nanoparticles and polyurethane nanoparticles were synthesized via the new process.The results of synthesis research demonstrated that the coupling of rotating packed bed(RPB)reactor and miniemulsion polymerization could intensify the process.The research contents of this paper are as follows:1.We designed a liquid sample cell with a simple structure,fewer parts and easy fabrication.The sample cell is used to visualize the formation process of polymer particles in emulsion and miniemulsion polymerization by confocal microscopy.The AIEgens were employed as fluorescent probes to label the droplet phase state during the polymerization process.The principle of visualization was based on the AIEgens aggregated state caused by the increase in viscosity of the local environment.Limited by equipment,the polymerization was triggered by a specific laser in an oxygen-rich environment.We studied the feasibility of photo-initiator reaction through the DFT calculation.Then,the processes of emulsion polymerization and miniemulsion polymerization were imaged by confocal microscopy.We found that there are two stages in the miniemulsion polymerization process.When the monomer concentration reaches a critical value,the phase separation would occur during the droplet nucleation polymerization.And we also found that,the droplet size affects the particle size and macroscopic reaction rate.2.The high-gravity miniemulsion polymerization process was designed and applied for the synthesis of ploystryene nanoparticles.The new process was based on the coupling of the RPB reactor and the miniemulsion polymerization reaction.We compared and studied the emulsion polymerization process,miniemulsion polymerization process and the high-gravity miniemulsion polymerization process,and found that the high-gravity process could shorten the reaction time from 300 min to 180 min;the particle size of the product is reduced from 1.1 ?m to 71 nm and the average molecular weight of the product is reduced from 83 kDa increased to 461 kDa.The use of RPB reactor for miniemulsion polymerization could maintain the small size and size uniformity of emulsion droplets in the absence of surfactant.Fluorescent nanoparticles doped with low-dose POSS-NH2 on the surface were synthesized based on the phenomenon of phase separation,and their preliminary application for liquid marbles was demonstrated.This modification method could realize the tremendous molecular use efficiency in surface modification field.3.The high-gravity miniemulsion copolymerization process was designed and applied for the synthesis of ployacrylate copolymer nanoparticles.The new process was based on the coupling of the RPB reactor and the miniemulsion copolymerization reaction.Oxidation-reduction composite initiator was used in the experiment to lower the reaction temperature from 80? to 40? to improve emulsion stability.We found that the Higee Tech could reduce the size of copolymer nanoparticles from 260 nm to 75 nm in a variety of monomer ratios,and the average molecular weight dispersion of the product from about 4.5 to about 3.The RPB reactor also could reduce the difference in the composition of copolymer and comonomer feed.A thermochromic material(HPS@PMMA-coBA)was designed based on the adjustable glass transition temperature of copolymer.The experimental results show that the prepared copolymer material will change the fluorescent color after being heated.The copolymer dispersion was then coated on non-fluorescent paper and dry at low temperature to make test paper.And the test strip was used to detect flash memory overloaded work.4.The high-gravity miniemulsion stepwise polymerization process was designed and applied for the synthesis of polyurethane(PU)nanodispersion to expand the scope of application.The new process was based on the coupling of the RPB reactor and the miniemulsion stepwise polymerization reaction.We found that the high-gravity miniemulsion polymerization process can improve the morphology of polymer particles,the stability of the polymer dispersion and the selecticity of reaction.Under the condition of G=200,a monodisperse and stable polyurethane nanoparticle dispersion with an average particle size of 137 nm can be prepared.The 1,1,2,3,4,5-hexaphenylsilole dyes(HPS),a kind of typical aggregation-induced emission luminogens,could be in situ loaded in PU nanoparticles,forming fluorescent nanodispersions of HPS@PU in aqueous solution.The preliminary applications of HPS@PU nanodispersion for in vitro fluorescent labeling of cells,transparent fluorescent films and anti-counterfeit printing inks were demonstrated.