A robust and high-throughput measurement platform for monomer reactivity ratios from surface-initiated polymerization
This article describes a robust approach to measure monomer reactivity ratios from surface-initiated copolymerization, by measuring composition of statistical copolymer brush surfaces using X-ray photoelectron spectroscopy. Statistical copolymer brushes were prepared from various monomer feeds by surface-initiated radical copolymerization at room temperature under ultraviolet (UV) irradiation. The copolymer brush composition data were fit to the terminal copolymerization kinetic model resulting in point estimates for the monomer reactivity ratios that are in good agreement with values measured under bulk reaction conditions. Additionally, a high-throughput approach was demonstrated to measure reactivity ratios using a single substrate exhibiting a gradient in copolymer brush composition. This high-throughput approach significantly reduces the time and effort required to generate reliable and reproducible point estimates of reactivity ratios, and these values are in good agreement with values obtained from both the discrete sample surface measurements and classical bulk analytical methods.