Pyrene label used as a scale for sequence-controlled functionalized polymers

Abstract

Living anionic polymerization (LAP) is a capable method for synthesizing sequence-controlled polymers (SCPs), and sequence-controlled functionalized polymers have been developed based on this method. However, experimental methods for determining the differences among various SCPs have been lacking in this field, even though polymeric sequences exhibit strong effects on the properties of SCPs. In this paper, a series of functionalized polymers with controlled sequences was synthesized by the LAP method, and the fluorescent molecule pyrene, which exhibits excimer emission, was introduced into these polymers through a thiol–ene click reaction to prepare pyrene-labeled SCPs. The study showed that differences in the sequences were reflected directly by the luminescence of pyrene moieties, specifically, the relationship between fluorescence feature of pyrene (I_E/I_M) and index of sequence feature (f_M) coincides with definite linear relation. Therefore, the pyrene label can be used as a quantitative scale for characterizing SCPs. In addition, molecular dynamics simulations of Py-labeled SCP molecular models with uniform DPSBD were carried out (DPSBD is the degree of polymerization of styrene sandwiched between adjacent functional 1,1-diphenylethylenes). The excellent agreement between simulations and experiments illustrated the reliability of the molecular model with uniform DPSBD. Therefore, DPSBD values in different sequence models could be used for the identification of SCPs, and they indicate the capability of LAP in controlling sequences.