Fully open-air surface initiated photochemically induced atom transfer radical polymerization of renewable α-methylene-γ-butyrolactone with potential in biomedical applications via post–functionalization

Abstract

There is an increasingly strong motivation within the polymer community, driven by environmental and economic factors, to adopt favourable and efficient synthesis techniques. Here, densely packed and highly uniform polymer brushes were synthesized from the Si-wafer surface using surface-initiated photochemically induced atom transfer radical polymerization (SI-photoATRP) of renewable monomer α-methylene-γ-butyrolactone. A thorough investigation of the various experimental parameters influencing the brush growth, initially performed under limited air conditions, finally enabled successful SI-photoATRP under fully open-air conditions, without using any additional chemicals for oxygen consumption. The method can operate efficiently at low catalyst concentrations (10–400 ppm) under ambient conditions using simple custom-made polymerization setups. Temporal control can be achieved under open-air conditions, while continuous polymerization is possible in complete darkness after brief UV exposure under limited air conditions. This approach offers potential economic benefits by significantly reducing energy consumption. The reusability of the reaction mixture for up to at least 6 cycles was demonstrated. Utilizing the lactone ring functionality of the grafted polymer brushes, we subsequently carried out post-functionalization studies using various diamines, followed by quaternization to impart antibacterial properties. In addition, functionalization with biotin hydrazide, with subsequent biotin-streptavidin complex formation can enable utilization of the brushes in various biochemical assays.