The first well-controlled aqueous atom-transfer radical polymerization (ATRP) conducted in the open air is reported. This air-tolerant ATRP was enabled by the continuous conversion of oxygen to carbon dioxide catalyzed by glucose oxidase (GOx), in the presence of glucose and sodium pyruvate as sequential sacrificial substrates. Controlled polymerization using initiators for continuous activator regeneration (ICAR) ATRP of oligo(ethylene oxide) methyl ether methacrylate (OEOMA, M =500) yielded polymers with low dispersity (1.09≤Đ≤1.29) and molecular weights (MWs) close to theoretical values in the presence of pyruvate. Without added pyruvates, lower MWs were observed due to generation of new chains by H O formed by reaction of O with GOx. Successful chain extension of POEOMA macroinitiator with OEOMA (Đ≤1.3) and Bovine Serum Albumin bioconjugates (Đ≤1.22) confirmed a well-controlled polymerization. The reactions in the open air in larger scale (25 mL) were also successful.

A new procedure for ultrasonication-induced atom transfer radical polymerization (sono-ATRP) in aqueous media was developed. Polymerizations of oligo(ethylene oxide) methyl ether methacrylate (OEOMA) and 2-hydroxyethyl acrylate (HEA) in water were successfully carried out in the presence of ppm amounts of CuBr 2 catalyst and tris(2pyridylmethyl)amine ligand when exposed to ultrasonication (40 kHz, 110 W) at room temperature. Aqueous sono-ATRP enabled polymerization of watersoluble monomers with excellent control over the molecular weight, dispersity, and high retention of chain-end functionality. Temporal control over the polymer chain growth was demonstrated by switching the ultrasound on/off due to the regeneration of activators by hydroxyl radicals formed by ultrasonication. The synthesis of a well-defined block copolymer and DNA− polymer biohybrid was also successful using this process.

In atom transfer radical polymerization (ATRP), radicals (R •) can react with Cu I /L catalysts forming organometallic complexes, R-Cu II /L (L = N-based ligand). R-Cu II /L favors additional catalyzed radical termination (CRT) pathways, which should be understood and harnessed to tune the polymerization outcome. Therefore, the preparation of precise polymer architectures by ATRP depends on the stability and on the role of R-Cu II /L intermediates. Herein, spectroscopic and electrochemical techniques were used to quantify the thermodynamic and kinetic parameters of the interactions between radicals and Cu catalysts. The effects of radical structure, catalyst structure, and solvent nature were investigated. The stability of R-Cu II /L depends on the radical stabilizing group in the following order: cyano > ester > phenyl. Primary radicals form the most stable R-Cu II /L species. Overall, the stability of R-Cu II /L does not significantly depend on the electronic properties of the ligand, contrary to the ATRP activity. Under typical ATRP conditions, the R-Cu II /L build-up and the CRT contribution may be suppressed by using more ATRP-active catalysts or solvents that promote a higher ATRP activity.

Polymer brush coatings are frequently prepared by radical polymerization, a notoriously oxygen sensitive process. Glucose oxidase (GOx) can inexpensively enable radical polymerization in solution by enzymatically consuming oxygen as it oxidizes glucose. Here, we report the growth of polymeric brushes using GOx-assisted atom transfer radical polymerization (ATRP) from a surface while open to air. Specifically, we grew a set of biomedically relevant polymer brushes, including poly­(oligo­(ethylene glycol) methacrylate) (POEGMA), poly­(2-dimethylaminoethyl methacrylate) (PDMAEMA), poly­(sulfobetaine methacrylate) (PSBMA), and poly­(2-(methylsulfinyl)­ethyl acrylate (PMSEA). For each of these polymers, we monitored GOx-assisted and GOx-free ATRP reaction kinetics in real time using quartz crystal microbalance (QCM) and verified findings with localized surface plasmon resonance (LSPR). We modeled brush growth kinetics considering bimolecular termination. This model fit our data well (r 2 > 0.987 for all samples) and shows the addition of GOx increased effective kinetic chain lengths, propagation rates, and reproducibility. We tested the antifouling properties of the polymer brush coatings against human blood plasma and were surprised to find that coatings prepared with GOx repelled more plasma proteins in all cases than their GOx-free counterparts.