Study On The Regulation Of BA And BA/MMA Radical Polymerization By Xanthene-9-Thione

Since the 20th century,acrylate polymers have been widely used in industry.Our research group has proposed a new system of controlled free radical polymerization mediated by the xanthene-9-thione,which has good control ability for styrene and acrylate monomers,and is expected to achieve industrial application.This paper studied the rule of n-butyl acrylate(BA)solution polymerization initiated by two kinds initiator,azobisisoheptonitrile(ABVN)/tert-butyl cumyl peroxide(TBCP),and methyl methacrylate(MMA)/BA copolymerization initiated by azodiisobuty-ronitrile(AIBN).There are three key influence factors carried on the the experiment:the mole ratio of initiator and XT,monomer mass concentration and initiator/monomer mole ratio.(1)The results showed that in the XT-regulated PBA,when ABVN/XT was between 1.3/1 and 2.0/1,the suitable monomer concentration can regulate the molecular weight of copolymerization product,and lower molar ratio of[BA]/[XT]makes the final product of PDI maintain in lower level.With ABVN as the initiator,the XT-regulated BA process can be divided into three stages.The first stage is the induction stage,where the polymerization conversion rate is basically zero,and most monomers do not participate in polymerization.In the second stage,the polymerization conversion rate increases rapidly and the number-average molecular weight decreases.The third stage is the low speed stage,in which most monomers are consumed,the polymerization conversion rate increases slowly,and PDI widens.With TBCP as the initiator,the higher the molar ratio of TBCP/XT,the higher the corresponding polymerization conversion rate and the higher the molecular weight growth.The molar ratio of TBCP/XT is too lower tha the polymerization is not happened.(2)Based on the study of BA/MMA copolymerization with AIBN as the initiator,it was found that AIBN:XT=1.3/1 was the most appropriate ratio of thermal initiator to XT.Under this condition,the conversion rates of the two monomers changed synchronously with the time curve,and the chemical composition of the copolymers was basically stable in the early and late stages of polymerization.As a result,sulfur ketone to join,makes the final copolymerization product more close to the chemical composition of feeding monomers.Meanwhile,the molecular weight of the copolymers increased to a large extent,and the PDI distribution could be controlled around 2.0.When both MMA and BA are the main monomers,MMA monomers will be consumed preferentially in the polymerization process.Only when MMA monomers are consumed to a certain concentration,BA will end its polymerization induction period and participate in polymerization.Increasing the total monomer mass concentration will widen the distribution of copolymers.