Preparation Of New Porous Polymer Microspheres By Multi - Emulsion Suspension Polymerization

Porous polymeric microsphere is a kind of polymeric materials with pore charter, the onethat is spherical in shape. It has gained increasing popularity in application of biomedicine,adsorption and purification, catalyst and degradation, chromatography and so on for itsadvantage of light density, lightweight and large surface area. Suspension polymerization,which can be considered as the least complicated heterogeneous polymerization technique interm of its simple mechanism and convenient process, is always chose to form porousmaterial. On the other hand, poly(HIPE) method which is based on the use of water in oil highinternal phase emulsions template (w/o HIPEs,>74%v/v internal droplet phase) strikeresearchers‘attention to form porous character. However, poly(HIPE)s are mostly preparedvia a bulk process, thereby yielding a monolith, the shape of which is limited by the reactionvessel. Although a spherical mould can contribute to make desired shape, the surface of themould might have an negative influence on the surface morphology of the resultingpoly(HIPE) and the process is tedious. So, the preferred strategy is to disperse HIPE in water(seems like w/o/w emulsion), subsequently solidified through polymerization. Not muchresearch on such new poly(HIPE) beads has been reported since. In other previous reports, themethods required delicate instrument to control the process definitely. In our work, to makeexperiment process cost-effective and simple as well as exploring a versatile method toprepare multiple and novel porous structure, HIPE-type w/o/w double emulsion templateformed by two step emulsification process was considered to be as a template to takesuspension polymerization for preparing porous polymeric microspheres with good potentialapplication in wastewater treatment field. That is an interesting and valuable project.The main task and result are list as follow:1. The first task is to fabricate novel porous polymeric microspheres based on HIPE-typew/o/w double emulsion template through two-step emulsification process. The obtainedporous poly(St-DVB) microspheres were collected by removing excess water after atraditional in-situ radical suspension polymerization. The recipe of preparation of novelporous microspheres was regulated for a better understanding of the morphology which wasinvestigated under the help of SEM analysis. The potential formation mechanism was study later. And then, the polymer/inorganics composite material was prepared on the basic of theoptimal recipe: the hydrophilic titanium dioxide(TiO2) was dispersed to water to form a newTiO2aqueous dispersion by an ultrasonic instrument in advance, and the left synthesizedprocedures were the same as the aforementioned preparation of poly(St-DVB) microspheres.The photocatalytic properties of polymer/TiO2composite microsphere were study. Judgingform the result, highly submicron particle-connective polymer microspheres with porouscharacter was fabricated successfully by our method, in which the pore was formed be theinterval of particles and not interconnected in the microspheres. The formation mechanism ofmicrospheres was linked to the oil/water bio-continuous structure due to reverse micelles. Ourmethod could play as a simple and versatile template to synthesis of polymer/inorganicscomposite materials, for it has the advantage of controllable loading efficiency of inorganics.The polymer/TiO2composite microsphere exhibited excellent photocatalytic property andfavorable cyclic catalytic performance.2. Basic on the result of previous research, in this work, to further study the effect ofsurfactant on the morphology of microspheres investigated by the SEM analysis, the porousmicrospheres ware fabricated with3different Span80concentrations (10%,25%,40%,respectively). The resultant products were modified by a sulfonation process, and theadsorption capacity of sulfonated microspheres was investigated in an aqueous solution of dye,rhodamine6G. Moreover, a further catalytic degradation application of Ag-loading compositepolymer microspheres was achieved by the reduction of PVP. Experimental results showedthat the porous structure of microspheres deeply depended on the concentration of surfactantwhich will significantly influent the stability of double emulsion and lead to the formation ofrevers micelles and the bio-continuous structure, there were3different porous structureformed under3different surfactant concentration and3kinds of microsphere exhibiteddifferent performance in the application to absorbing wastewater contaminant and catalyticsupport.