Synthesis And Characterization Of Functional Polystyrene Microspheres

Polymer microspheres have been used in coatings, adhensives, plastic additives,biochemistry and elctronical information. The study on polymer microspheres isdivided into two classes:preparation and application.We can choose a few methods to prepare polymer microspheres. The propertiesof polymers'surface are closely bounded up with those of polymers.After a few methods are valued, Poly(St-co-MAA) microspheres have beensynthesized by emulsifier-free polymerization. Water was dispersing medium andstyrene was monomer and methacrylic acid was comonomer. We account for thevirtues of emulsifier-free polymerization which dosen't need surfactants and hasclean surface.We designed a series of tests to study particle nucleation mechanism undervarious conditions.The effective diameter of Poly(St-co-MAA) microspheres has been found tobe increasing with polymerization time. On the contrary, the polydispersitydecreased.It shows that although hydrophile comonomer is involved,microspheresare not still steady enough.The tendencies are different when different electrolytes are added.With the amount of NaCl , the effective diameter of Poly(St-co-MAA)microspheres increases as well as polydispersity of polymer microspheres. Thepossible reason is maybe that more cation compress double-layer of latexes. Thisleads to more and more precarious initial particles which are apt to coagulate andthen larger polymer microsphers generated.When equal amount of NaHCO3 was added into the system , both effectivediameter and polydispersity of Poly(St-co-MAA) microspheres are less than thoseof polymer spheres generated with NaCl. NaHCO3 can neutralize the carboxylgroups on polymer spheres and increase charges on polymer surfaces which makesthem more steady.While equal amount of MgSO4 was added ,bulks occurred in 5 hours. Weconcluded that high ion intensity of MgSO4 compressed double-layer and themicrospheres quickly coagulated.The effect of solvents on effect diameter of polymer microspheres was studiedand possible mechanism was suggested according to the tendencies.In St/MAA/kps system , polar solvents(ethanol and glycerin)and nonpolarsolvents were added indifferently.The effective diameter increased with the amount of ethanol while thepolydispersity showed the opposite tendency;when glycerin was added , theeffective diameter and the polydispersity increased at the same time .Nonpolar solvent decreaed the polydispersity of microspheres and made thediameter larger. Then we compared the difference between the two nucleationfashion .Then , silver nanoparticles generated on the surfaces of the copolymer particleswith carboxyl groups on their surface by simple silver mirror reaction. Thecharacterization was performed by IR,UV-vis, EDX, SEM.The effect of various amount of glucose and AgNO3(reducing agent)onmorpholygy of Ag-latex composites was studied by means of EDX and SEM. Thereaction place was confirmed.