One Reagent with Two Functions: Simultaneous Living Radical Polymerization and Chain-End Substitution for Tailoring Polymer Dispersity.

The molecular weight distribution of polymer, termed dispersity ( Đ ), is a fundamental parameter that determines polymer properties. Sodium azide (NaN 3 ) functions as a catalyst in organocatalyzed living radical polymerization when the reaction medium is nonpolar. In contrast, NaN 3 can act as a nucleophile when the reaction medium is polar. In this paper, we report an efficient approach to dispersity control by exploiting the dual functions of NaN 3 under the varied solvent polarity. Simultaneous polymerization and chain-end substitution allowed us to tune the Đ values of various polymethacrylates and poly(butyl acrylate). Notably, the Đ value could be tuned to a wide range approximately from 1.2 to 2.0 for polymethacrylates and to 3.8 for poly(butyl acrylate). This approach afforded polymer brushes on surfaces with tailored Đ values. An interesting finding was that the polymer brushes exhibited a unique interaction with external molecules, depending on the Đ value.