Polymer Microgels Microfluidic Fabrication And The Regulation Investigation Of The Morphology And Functionlity

Recently, preparation of polymer microparticles with tunable morphology based on polymer micro/nanogels could be achieved by microfluidic technique, combinning physical or chemical cross linking methods. Owning to the finely tunable diameters and morphology of the particles by microfluidic technique, it have been widely applied to the fabrication of drug delivery materials, photonic structured materials and complex structured materials, among others.Uniform alginate sodium based single emulsion and double emulsion droplets were created through microfluidic technique. By combinning external ionic cross linking and adjustment of external collecting solutions viscosity, we could achieve the regulation of the resultingmicrogels’ morphology. Also, the formation mechnism of the different morphology microgels was discussed. By utilization of the precipitation polymerization method, we produce monodisperse poly-N-isopropylacrylamide nanogels which can be used to form colorful photonic crystal dispersions. Core/shell photonic crystal microspheres using photo polymerizable resin as shell, nanogels based photonic crystal dispersions as the core can be prepared by double emulsion microfluidic technique, combinning UV light solidification method. Then, the Janus photonic crystal microspheres based on the core/shell microsphere were formed by a simple centrifugation method. Relatonship between the Janus structure and centrifugation conditions was also investigated. This dissertaion are consisted of several sections as the following:1. Uniform alginate sodium emulsion droplets were created by microfluidic technique. The emulsion droplets were cross-linked by using aqueous solution of barium acetate(or calcium chloride) and glycerol as the collecting solution. Morphology of the microgels were tuned by tailoring the viscosity of the collecting solution by simply varying the concentrations of glycerol. The morphology variation was measured by optical microscopy and scanning electron microscopy(SEM). The drug release experiment was conducted by using the microgels as the drug delivery carrier, and the result indicate the morphology of the microgels have significant impact on the drug release behavior.2. Monodisperse double emulsion droplets with alginate sodium solution as the shell and nitromethane solution as the core were created by microfluidic technique. The emulsion droplets were collected by different viscosities of collecting solution and different morphology of microgels were obtained. The resultanting microgels morphology variation trend was systematically investigated. The effects of the double emulsion droplets’sturcture, concentration of alginate sodium solutions and the component of the droplets’core part on the microgels morphology was systematically investigated. The formation mechanism of different morphology microgels was studied.3. The monodispersed poly-N-isopropylacrylamide nanogel particles were synthesized by precipitation polymerization method. Different colors of nanogel dispersions were obtained by controlling evaperation self assembly method. Different colors of core/shell photonic crystal microsphereswere obtained by empolying the photopolymerizable ethoxylated trimethylolpropane triacrylate (ETPTA) resin as the shell part and the colorful nanogel dispersions as the inner core. The microsphere’s optical property variation trend with the temperature change was investigasted. The microspheres were functionlized by addition of small fluorescent molecules and quantum dots (QDs). The Janus supraparticles based on the above mentioned core/shell microspheres were formed through a centrifuge force induced method. The effect of the centrifugation temperature, centrifugation speed and centrifugation time on the microsphere’s inner morphologywere systematically investigated. Optical properties variation trend with the microsphere’s inner structure change was studied. Double stop band photonic crystal microspherses were successfully prepared by addition of the monodisperse SiO2nanoparticles into the shell part. The monodisperse Au nanoparticles were synthesized by the sodium citrate hydrothermal reduction. Core/shell hybrid nanogel particles with the gold nanoparticles as the core and the poly-N-isopropylacrylamide as the shell were fabricated by the traditional emulsion polymerization method. The amount of the gold nanoparticles inside the hybrid nanogels could be controlled by the addition the gold nanoparticles dispersion’s volume.The hybrid nanogels photonic crystal structured microspheres were formed by using the hybrid nanogel dispersions as the building blocks assisted by the annealing method. The effect of hybrid nanogels’concentration on the microspheres’optical property was also investigated.