Synthesis Of Micron Sized,Monodisperse,Crosslinked PS-DVB Microspheres

In this paper,the crosslinking PS-DVB micro-spheres were synthesized with the seed swelling method and dispersion polymerization method.The ultrasonic technology was introduced in the seed swelling method to shorten the reaction time.The mixed solution of ethanol/ethylene dichloride was the solvent of the dispersion polymerization.The effects of the the various reaction conditions on the crosslinked PS-DVB microspheres morphology,particle size and the crosslinking degree were studied with scanning electron microscope,infrared spectrum analysis and soxhlet method.The following conclusions were got:(1)The particle size and the size distribution of the PS microspheres synthesized with the dispersion polymerization method were increased with the the increase of St concentration.The influence of PVP on the particle size was very small.When the water was more than 30%,particle size distribution was significantly widen.Monodisperse PS microspheres require the St within 10% ~ 30%,PVP within the scope of 7% ~ 10%,the proportion of water within 20%.(2)The introduction of the ultrasonic technology into the seed swelling method greatly shortened the reaction time.The crosslinking degree of the PS-DVB was higher with the ultrasonic time increasing when the ultrasonic time was less than 30 minutes.But,when it was more than 30 minutes,with the ultrasonic time increasing,the crosslinking degree was remain unchanged.When the St/DVB increased from5:1to 11:1,the crosslinking degree fell from 79.48% to 64.60%.(3)In dispersion polymerization method,when the solvent was ethanol/ethylene dichloride(ethanol:ethylene dichloride=100:5)and St was 20%,monodisperse particles could be obtained containing up to 6 wt % DVB based on styrene and the particle was about 7.69?m by adding DVB into the reaction after 2.5h.The particle size and the size distribution of the crosslinked PS-DVB micro-spheres were both increasing with the increasing of the DVB and ethylene dichloride.The optimum reaction conditions of synthesizing crosslinked PS-DVB micro-spheres was that St was 20%~25%,ethanol/ethylene dichloride was 100/5~100/10.When the monomer concentration was 10%,20%,25% and 20% respectively,the corresponding best time of beginning to add DVB was 1.5h,2.5h,3h and 4.5h.