Kinetic analysis of surface‐initiated SET‐LRP of poly(N‐isopropylacrylamide)

Abstract

The single-electron transfer living radical polymerization (SET-LRP) of N-isopropylacrylamide (NIPAM) from silicon wafer modified with an initiator layer composed of 2bromopropionyl bromide (2-BPB) fragments is described. The amount of Cu(0) generated in situ by the disproportination of Cu(I) to Cu(0) and Cu(II) in the presence of 2,2 0 -bipyridine (2,2 0bpy) ligand and N,N-dimethylformamide (DMF) solvent at 90 C is dependent on the ratio of [CuBr]/[CuBr 2 ]. By proper selection of the [CuBr]/[CuBr 2 ] ratio, well-controlled SET-LRP polymerization of NIPAM was observed such that the thickness of the layer consisting of chains grown from the surface increased linearly with the molecular weight of chains polymerized in solution in identical. In addition, the calculation of grafting parameters, including surface coverage, r (mg/m 2 ); grafting density, R (chain/nm 2 ); and average distance between grafting sites, D (nm), from the number-average molecular weight, M n (g/mol), and ellipsometric thickness, h (nm), values indicated the synthesis of densely grafted poly(NIPAM) films and allowed us to predict a ''brush-like'' conformation. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 5842-5847, 2010

SET–LRP of N‐isopropylacrylamide in the presence of chain transfer agent

“…For the fast disproportionation of Cu(I), highly polar solvents such as dimethyl sulfoxide,1, 9, 10 DMF,11 branched alcohols,4 and binary mixtures of organic solvents12 in combination with N ‐ligands3 such as 2,2′‐bipyridine (2,2′‐bpy), tris(2‐(dimethylamino) ethyl)amine (Me 6 ‐TREN), tris(2‐aminoethyl)amine, N,N,N′,N″ ‐pentamethyldiethylenetriamine, and poly(ethylene imine) are used. Thus, the uses of polar solvents with hydrogen bonding and a chlorine‐ or bromide‐initiator giving stronger growing terminal was found to be effective to prevent undesirable reactions.…”

Facile preparation of superhydrophobic and oleophobic surfaces via the combination of Cu(0)‐mediated reversible‐deactivation radical polymerization and click chemistry

“…However, the development of multiphase SET‐LRP has expanded the solvent classes that can be used, including less disproportionating solvents, such as acetonitrile and acetone, and even the mixture of ethanol and water with non‐disproportionating solvents, such as hexanes, cyclohexane, ethyl acetate, diethyl carbonate, toluene, and anisole . These improvements together with the intrinsic advantages of the Cu(0)‐mediated RDRP process, such as high reaction rates, tolerance to air, impurities, and radical inhibitors, and near perfect chain‐end fidelity, make it a method of choice for performing surface initiated RDRP reactions …”

Stimuli‐responsive diblock copolymer brushes via combination of “click chemistry” and living radical polymerization

“…Recently “living” polymerizations have been applied to grafting polymers from surfaces via “grafting‐from” technique. Among all the polymerizations for the synthesis of dense polymer brush, living radical polymerization, such as nitroxide‐mediated radical polymerization, atom‐transfer radical polymerization (ATRP), reversible addition‐fragmentation chain‐transfer (RAFT) polymerization, and single‐electron transfer‐living radical polymerization (SET‐LRP), is the most important one owing to its ease to control the thickness and the composition of the brush.…”