XT-mediated Miniemulsion Polymerization Of MMA And Synthesis Of Core/shell Micrpspheres Of PMMA/PBA

The research on controlled/living free radical polymerization in miniemulsion is one of the hotspots in the field of polymer chemistry.To overcome the the shortcomings of conventional controlled/living radical polymerization,our group has proposed the xanthene-9-thione(XT)mediated polymerization,which acts on the polymerization of most monomers in mild conditions.In this dissertation,XT-mediated miniemulsion polymerization of MMA was studied,and based on that,cross-linked PMMA microspheres were prepared.Then PMMA/PBA core-shell particles were further prepared by seeded emulsion polymerization initiated by macromolecule initiator of PMMA.The content is as follows:1.Study on miniemulsion polymerization of MMA.In this section,XT-mediated miniemulsion polymerization of MMA was initiated by azobisisobutyronitrile(AIBN)or di(p-tert-butylcyclohexylperoxide)(TBCP).The relative molecular weight and the morphology of the polymer was characterized by GPC and SEM,and it shows that the conversion of AIBN-initiated polymerization is higher than that of TBCP-initiated polymerization,and the conversion increases with the decrease of amount of XT,the increase of the amount of emulsifier and the increase of polymerization temperature.Besides,the number average molecular weight(Mn)increases approximately linearly with the conversion,and there is a larger increase in Mn of polymer parepared with the initiation of TBCP,which means that low temperature is favorable for the mediation of XT.Last but not least,monodispersed PMMA microspheres with fine morphology can be prepared by XT mediated miniemulsion polymerization,and the size of microspheres is approximately 100 nm,which extends the application of XT-mediated polymerization.2.Preparation of crosslinked PMMA microspheres.On the basis of XT-mediated miniemulsion polymerization of MMA,cross-linked PMMA microspheres were prepared using AIBN or TBCP as initiator and ethylene glycol dimethacrylate(EGDMA)as crosslinker.The size and morphology of the microspheres were characterized by SEM,and it shows that when prepared with a crosslinker content of 3%of MMA,the cross-linked microspheres with a particle size of about 110 nm are almost monodispersed.3.Preparation of PMMA/PBA core-shell particles.The cross-linked PMMA microspheres prepared by XT-mediated miniemulsion polymerization were further used in the seeded emulsion polymerization of BA for initiation.The morphology of microspheres was characterized by DLS,SEM and TEM.and it shows that when the crosslinker in the core accounted for 3%of MMA's mass,the mass ratio of MMA to BA is 1:1 and BA is fed by equilibrium swelling progress,PMMA/PBA particles with clear core-shell structure can be prepared,and PBA/PMMA particles can be prepared when semicontinuous progress is utilized to feed BA,which offers new ideas for using XT-mediated polymerization to prepare microspheres with special structure.