Study On Anionic Polymerization Of Dienes Using An Initiator Composed Of N-Butyllithium/Triisobutyl Aluminum/Dodecyl Benzene Sulfonic Acid Barium

The butadiene, isoprene and styrene were initiated by a initiator system composed of n-butyl lithium,triisobutyl aluminum,dodecyl benzene sulfonic acid barium with cyclohexane as solvent at 40℃-80℃. The polymer were characterized by NMR,GPC, DSC, also studied the influence of the initiator ratio, reaction temperature, for trans content,con-version,molecular weight and its distribution, etc. The main results and conclusions are as follows:Dodecyl benzene sulfonic acid barium(BDBS) was synthesized at room temperature in this paper first,compared to other preparations of organic barium salt,it's condition is mild,as well as easy operation.And a initiator system was composed of n-butyl lithium(Li),triisobutyl aluminu-m(Al),dodecyl benzene sulfonic acid barium(Ba) to synthesize high trans-1,4-polybutadiene by anionic polymerization. In the process of synthesis,we got the best addition order is Ba-Al-Li, meanwhile Ba and Al must be aged for 10min,and then Li was added. Using this process we can obtain high trans-1,4-polybutadiene with a high monomer conversion at 50℃.Fixed [Al]/[Li]=1.0, the trans-1,4 content of polybutadiene increased first,and then decreased along with the increasing of [Ba]/[Li],and the monomer conversion decreased gradually.The PB with the highest number of 1,4-trans content(87%)was produced in [Ba]/[Li]=0.25,while 1,2-content of polybutadiene is 1.9%. Fixed [Ba]/[Li]=0.25, the trans-1,4 content of polybutadiene increased,1,2-content of polybutadiene decreased,along with the increasing of [Al]/[Li] ratio,and the rate of polymerization reaetion decreased at the same time.The retarding effect was very obvious when [Al]/[Li] ratio was bigger than 1.0,the best range of regulation 1,4-trans content of PB is 0.5～1.0.The 1,4-trans content decreased with increasing the polymerization temperature.The PB with the highest number of 1,4-trans content (87%) was produced at 50℃.The DSC result indicated that PB transformed from amorphous phase to semi-crystalline phase with increasing the number of 1,4-trans content of PB, Tg and Tm increased also.However, the initiator system was not so efficient for the regulation of isoprene's microstructure.The initiator system has a low activity for Bd-St copolymerization.