Sequence Features of Sequence-Controlled Polymers Synthesized by 1,1-Diphenylethylene Derivatives with Similar Reactivity during Living Anionic Polymerization

Abstract

Living anionic polymerization (LAP) is the primary representative method of living polymerization and exhibits the ability to synthesize sequence-regulated functionalized polymers. However, there has always been a lack of special features for LAP to guide these cutting-edge syntheses in sequence-controlled polymers. In this study, the copolymerizations of a series of alkyl-substituted 1,1-diphenylethylene derivatives (DPE-alkyls), which display similar reactivities but different structures, and St were performed. In addition, the processes of whole chain propagation were monitored by the in situ 1H NMR method. The results show that changing the alkyl type of DPE-alkyls has little influence on their sequence distributions during copolymerization. Therefore, we could deduce a reasonable principle called “sequence equivalence” in LAP: the copolymers of different DPE derivatives and St would have identical sequence structures when DPE derivatives exhibit exactly the same reactivity ratio (rSt) during the copolymerization under the same conditions. Furthermore, the combination of in situ 1H NMR experiments and kinetic Monte Carlo model (KMC) simulations was conducted synchronously. The results of simulations show that the KMC model not only can simulate detailed information for LAP of DPE derivative and St but also could quantify the precision of the corresponding sequence distributions. Additionally, the KMC model that we constructed for the simulation of sequence control in LAP can give us a new insight into the possibility of sequence tailoring. Next, the relationship among the glass transition temperatures (Tgs), types of alkyl substituent, and sequence structures of DPE derivative units in the chains was investigated. Through DSC analysis, this study’s results indicated that polymers with similar sequences but different alkyl substituents present contrasting differences in thermal property. These results could provide a broader understanding of the thermal properties of polymers.