Thermo-Responsive Polymer Brushes with Tunable Collapse Temperature in the Physiological Range Supplementary Information p.S1 Supplementary Information to: Thermo-Responsive Polymer Brushes with Tunable Collapse Temperatures in the Physiological Range Alain M. Jonas,* Karine Glinel, Ron Oren, Bernard Nysten, and Wilhelm T. S. Huck* (*) correspondence to alain.jonas@uclouvain.be and wtsh2@cam.ac.uk Experimental section Brush synthesis Materials. All chemicals were analytical reagent grade (unless otherwise stated). Di(ethylene glycol) methyl ether methacrylate (MEO 2 MA) (95%), and oligo(ethylene glycol) methyl ether methacrylate (OEGMA), molar mass ~475 g/mol, were obtained from Aldrich. Prior to reactions, they were passed thrice through a column of activated basic alumina to remove inhibitors. All solvents were distilled before use, except methanol which was analytical reagent grade. Water was Milli-Q grade (resistivity higher than 18.2 MΩ.cm) obtained from a Millipore Simplicity 185 system. Copper(I) chloride (99.995+%) (Cu I Cl), copper(II) chloride (99.999+%) (Cu II Cl 2 ) and 2,2'- dipyridyl (99+%) (bipy) were from Aldrich. Silicon wafers (<100> orientation) were obtained from Compact Technology Ltd; they were cleaned for 10 min. in an air plasma asher (100 W, Emitech K1050X) before use. Preparation of initiator-grafted silicon wafers. The synthesis of the 2-bromo-2-methyl propionic acid 3-trichlorosilanyl-propyl ester was adapted from previously published procedures, 1 and the formation of the initiator monolayer was performed as described previously. 2 An ellipsometric thickness of 0.6-0.9 nm was found for the initiator monolayer. Surface-initiated ATRP. The monomer (95 mmol) was dissolved in a mixture of water (30 mL) and CH 3 OH (15 mL) (e.g., for a MEO 2 MA:OEGMA molar ratio of 90:10, 16.11 g of MEO 2 MA (85.5 mmol) and 4.51 g of OEGMA (9.5 mmol) were used) in a round-bottom flask sealed with a rubber septum. Bipy (5 mmol, 782 mg) and Cu II Cl 2 (0.16 mmol, 21.5 mg) were added to this solution, which was stirred and degassed with a stream of nitrogen for one hour. Cu I Cl (1.6 mmol, 158.5 mg) was then added quickly to the solution. The solution was stirred and degassed for 45 further min. Meanwhile, the initiator-grafted Si wafers were sealed into Schlenk tubes and were degassed (4 vacuum/N 2 filling cycles). The polymerization solution was then syringed and quickly transferred to the Schlenk tubes. After various polymerization times at room temperature under an overpressure of nitrogen in the absence of stirring, the samples were removed, washed with water then methanol, dried with a stream of N 2 and stored under nitrogen before use. For all experiments, the ratio between methacrylate moieties, Cu (I) and Cu (II) was kept constant, as well as the total molar concentration in monomer.