Synthesis of Chain Transfer Agent (S)-Benzyl Dithiobenzoate (BTBA)

SUPPORTING INFORMATION

Synthesis of chain transfer agent (S)-benzyl dithiobenzoate (BTBA)

The dithioester chain transfer agent (S)-benzyl dithiobenzoate (BTBA) as described below. A mixture of benzyl alcohol (2.168 g, 2.077 mL, 20 mmol), benzoic acid (2.442 g,

20 mmol), and phosphorus pentasulfide (4.445 g, 10 mmol, 50 mol %) in 1,2- dichloroethane (60 mL) was refluxed for 20 h. After cooling to room temperature, the reaction mixture was passed through a chromatography column packed with neutral alumina eluting with toluene. A red-colored oil-like product was obtained after the solvents were removed by rotary evaporation.

Preparation of P (St-alt-MAn)-b-PSt via RAFT Polymerization

The P(St-alt-MAn)100-b-PSt221was prepared by mixing 46.8 g styrene, 4.9 g maleic anhydride and a suitable volume of dioxane in a three-necked flask, immersed in an ice water/NaCl mixture at about -10°C. The mixture was degassed by applying a vacuum and back filling with nitrogen for three cycles, followed by the addition of 0.25 g of BTBA and 0.1 g of AIBN. The procedure was repeated for a further three cycles. The molar ratio of reaction materials was adjusted to [MAn]: [St]: [BTBA]: [AIBN]=100:900:2:1 with [MAn]= 0.2 mol L-1. The three-necked flask was equipped with a thermometer, condenser and nitrogen input tubing and the flask was immersed in an oil bath at 60 °C for 24 h under a nitrogen atmosphere. The polymerization reaction was terminated by rapidly cooling to room temperature and the polymer precipitated by pouring the polymer solution into diethyl ether. Purification was achieved by solubilising the polymer in THF and precipitating the polymer by pouring into diethyl ether. This was repeated three times and the product dried in a vacuum oven at 35°C for 24 h.

Gel permeation chromatography (GPC):

The measurements of molecular weight and molecular weight distribution of the polymers were carried out on a gel permeation chromatograph (GPC) system equipped with JASCO PU-980 HPLC pump and a Evaporative Light-scattering Detector (Alltech

2000). A Jordi GPC Column (Alltech, 300  7.8 mm, 5 µm particle size, 1000 Å pore sizes) was used to elute the THF solutions of polymers (10 mg of (co)polymer in 5 mL of

THF, 50 µl injected in each run) at 25 °C. Calibration was performed with polystyrene standards using Cirrus 3.0 software (Polymer Laboratories). THF was used as the eluent at a flow rate of 1.0 mL min-1.

Elemental analysis

The elemental analysis for carbon and hydrogen in the copolymers was performed by the Campbell Microanalytical laboratory, Department of Chemistry, University of Otago, using a Carlo Erba 1108 Elemental Analyzer. The proportion of oxygen was calculated by difference.

NMR 1H NMR spectra were recorded on a 500 MHz Oxford 500 spectrometer. Samples were

-1 prepared with concentrations of about 10 mg mL in DCCl3, and 64 scans were collected at room temperature. Chemical shifts were given in ppm using the solvent peak as the reference.

Differential scanning calorimetry (DSC)

The thermodynamic properties of the polymers were measured using differential scanning calorimetry (DSC, Pyris 1, Perkin Elmer, USA) at a heating rate of 5 °C min1 under nitrogen. Polymer samples were sealed in pre-weighed aluminium pans (24.50 ±

0.04 mg) and the sample weight (4.36 mg) was confirmed after each scan. The temperature of the DSC was calibrated with water (>99.994%, Aldrich, USA) and indium

(>99.99%, Perkin Elmer, USA).