Comparison of Long-Term Stability of Initiating Monolayers in Surface-Initiated Controlled Radical Polymerizations

The reproducibility of polymer brush synthesis via surface-initiated controlled radical polymerization is interrogated. Experiments compare the stability of initiating monolayers for surface-initiated (SI) reversible addition-fragmentation chain transfer polymerization (SI-RAFT) and SI atom transfer radical polymerization (SI-ATRP). Initiator-functionalized substrates are stored under various conditions and grafting densities of the resulting polymer brush films are determined via in situ ellipsometry. Decomposition of one of the examined SI-RAFT initiators results in limited reproducibility for polymer brush surface modification. In contrast, initiators for SI-ATRP show excellent stability and reproducibility. While both techniques bring inherent benefits and limitations, the described findings will help scientists choose the most efficient technique for their goals in chemical and topographical surface modification.