Miniemulsion Polymerization Of Styrene And Butyl Acrylate Emulsified By High-speed Shearing

Miniemulsion which is carried by droplet nucleation of small monomerdroplet(50~500nm) prepared by high strength homogenization in the presence ofemulsifier and co-stabilizer is one of emulsion polymerization techniques. Comparedwith the conventional emulsion polymerization, not only the stability of miniemulsionis higher, but also the size and size distribution of monomer droplet and latex particlecan be controlled during the polymerization.In the paper, styrene(St) and butyl acrylate(BA) are used as monomers, dodecyl-trimethylammonium bromide(DTAB) is used as emulsifier, hexadecane(HD) is usedas co-stabilizer, azobisisobutyronitrile(AIBN) is used as oil-soluble initiator andazobis isobutyl amidine hydrochloride(V50) is used as water-soluble initiatorrespectively, high speed emulsifying machine is used as miniemulsificationequipment to prepare P(St/BA) emulsion of large size and wide size distribution. AlsoS,S’-bis(,-dimethyl--acetic acid)(BDAT) is added to prepare symmetric triblockpolymer as RAFT agent.During the miniemulsification process, the influence of shear condition, emulsifierand co-stabilizer on the size and size distribution of monomer droplet is resea rched.The ratio of droplet nucleation in the miniemulsion can be improved by suitableemulsifier concentration, internal phase initiator and low BA content. Styrene/acrylicemulsion of high solid content(60wt%) is prepared by miniemulsion and seedemulsion polymerization. In miniemulsion RAFT polymerization, the influence ofemulsifier, swelling ratio and block sequence on the miniemulsion stability, molecularweight and molecular weight distribution of block polymer is researched.In the experiment, Nano-ZS, SEM and GPC are used to characterize monomerdroplet and polymer emulsion. It can be found that the size of monomer droplets andlatex ranges from200to700nm, size distribution ranges from0.2to0.6. The latex ofhigh solid emulsion prepared appears large size and bimodal distribution. Molecularweight and molecular weight distribution of triblock polymer can be controlled byemulsifier combined and AIBN. And super swelling effect is effectively suppressed.