Investigation Of The Copolymerization Characteristics Of Styrene Derivatives Containing ?-annular Substitutes In Living Anionic Polymerization

Sequence-controlled polymers have specific arrangement of monomer units.The change of sequence structure brings about changes in polymer properties.Therefore,the synthesis of sequence-controlled polymers has become an extremely important research field in polymer chemistry,and the corresponding synthesis methods have also made remarkable progress.In living anionic polymerization(LAP),substituents containing steric hindrance was introduced into styrene derivatives to control the polymer sequence structure by regulating their kinetic behavior.As a typical example,1,1-diphenylethylene(DPE)as a special styrene derivative that cannot homopolymerize,but can copolymerize with other monomers due to the influence of bulky substitute,thus,it can be used as sequence-controlled monomer in LAP.In addition,whether the prime features of polymerization can be maintained when another flexible and saturated substituent is applied to replace one of the phenyls became worthy of consideration.Moreover,the influence of the introduction of cycloalkane on the physical properties of polymers(glass transition temperature and transparency,etc.)has become a worthy problem to further study.Based on the above problem,five styrene derivatives with annular substituents(SAs)were successfully synthesized and the feature in living anionic polymerization was investigated in this paper.Meanwhile,the reactivity of SAs monomer was investigated by combining density functional theoretical(DFT)calculation results with experimental results.Moreover,the high reactivity of META was copolymerized with isoprene(Ip)to control the sequence distribution of monomer units in the chain by adding additives.Thus,sequence-controlled polymerization can be enriched in living anionic polymerization through this method.1.Five styrene derivatives with annular substituents(SAs)were successfully synthesized.Among these SAs,(1-cyclopentylvinyl)benzene(CPBE)and(1-cyclohexylvinyl)benzene(CHBE)possessed dissociative cycloparaffins as the ?-substituent in the styrene structure,while 1-methylene-1,2,3,4-tetrahydronaphthalene(THNE)and 5-methylene6,7,8,9-tetrahydro-5H-benzo[7]annulene(THBE)exhibited vinyl-substituted benzo-cycloalkanes.Additionally,the 4-methylenethiochromane(META)monomer showed a similar structure to that of THNE,but with a sulfur atom in the benzo-cycloalkane.During living anionic polymerization of these SAs monomers cannot be homo-polymerized,but can be copolymerized with styrene,and the reactivity of SAs are as following: META>THNE>THBE?CPBE?CHBE.Based on the actual results of the specific features of the SAs,the sequence-controlled monomers with various structures were designed and synthesized by changing the substituents of electronegativity and steric hindrance,which provided guidance for the design and synthesis of new sequence-controlled monomers.2.The copolymerization of META with isoprene(Ip)was conducted,and sequencecontrolled polymers with well-defined sequence distribution and microstructure were obtained.META is difficult incorporated into the polymer chain and low reactivity that META exhibited during the copolymerization without additives.Tetrahydrofuran(THF)and N,N,N',N'-tetramethylethylenediamine(TMEDA)as polar additives which can be applied to increase the reactivity of META and the polymers with gradient structure can be obtained.More importantly,when sodium 2,3-dimethylpentan-3-olate(NaODP)or potassium tert-butoxide(t-BuOK)was added into the reaction,the obtained polymers were in alternating or near-alternating structure.