Metal-free multicomponent polymerization toward cationic polyamidines

Cationic polymers, also known as polycations, are considered to be the most potential non-viral gene carriers due to their unique advantages such as the ability to bind the negative charge of nucleic acid molecules. Multicomponent polymerization (MCP) is a one-step, tandem strategy to construct complex structures based on multicomponent reactions. Herein, we developed a metal-free MCP method based on three monomers of p-dinitrovinylbenzene (p-DNVB), 1,1-dimethylethyl N,N-dibromocarbamate (BocNBr₂), and bis-secondary-amines with a ratio of 1:2:1, to access a library of Boc-substituted polyamidines with well-defined structures and suitable molecular weights (M_w ranging from 4400 Da to 11,000 Da) in high yields (up to 85%) under mild conditions. Upon the removal of Boc groups, a series of water-soluble polymers with cationic property were prepared and their gene binding capability was further evaluated.