Thiol silicone oil,prepared from octamethylcyclotetrasiloxane and mercaptopropyl methyl dimethoxy silane,was reacted with CS2,and 2-bromoisobutyrate methyl to synthesize organosilicon-based reversible addition-fragmentation chain transfer(RAFT)reagent(RAFT-SSO).And polyether modified organosilicon defoamer(RS-EOPO)was finally obtained from RAFT polymerization of RAFT-SSO with methyl terminated allyl polyoxyethylene ether(EO)and methyl terminated allyl polyoxypropylene ether(PO).RS-EOPO was characterized by FTIR,1HNMR and GPC for structural analysis,and further evaluated for its performance on defoaming,antifoaming and compatibility in comparison to imported defoamer.The optimal synthesis conditions of RS-EOPO were obtained as follows:relative molecular mass of RAFT-SSO 2000,m(EO)∶m(PO)=1∶4,m(RAFT-SSO)∶m[ether(EO and PO)]=1∶1.15,reaction temperature 75 ℃,reaction time 8 h,initiator amount being 2％of the total mass of EO(3.45 g)and PO.Under the above reaction conditions,the yield of RS-EOPO reached 91.8％.
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