Plgel mixed d columns

Size exclusion chromatography (SEC) experiments were performed on an Agilent 1200 series HPLC system equipped with an Agilent PLgel mixed guard column (particle size = 5 µm) and two Agilent PLgel mixed-D columns (ID = 7.5 mm, L = 300 mm, particle size = 5 µm). Signals were recorded by a UV detector (Agilent 1200 series), an Optilab REX interferometric refractometer, and a miniDawn TREOS light scattering detector (Wyatt Technology Corp.). Samples were run using THF as the eluent at 30 °C and a flow rate of 1.0 mL/min. Data analyses were carried out on Astra software (Wyatt Technology Corp.) and molecular weights were determined based on narrow molecular weight poly(styrene) standards. Polymer 2 had a Mn = 6,700 g/mol , weight-average molecular weight (Mw) = 13,000 g/mol, dispersity (Ð) = 1.95. (see Supporting Information, Figure S6). The relatively high dispersity is common for atom transfer radical polymerization (ATRP) of OEG3A monomers without the introduction of CuX2 deactivator species. 47 (link) The deprotected POEG3A had a Mn = 5,100 g/mol, Mw = 10,000 g/mol, Ð = 1.95 (see Supporting Information, Figure S5 -S6, Table S1). However, in this article, the Mn of 17,700 g/mol determined by NMR is quoted, as this method gives a more accurate estimate of the molecular weight, than SEC with a polystyrene standard.

The copolymer was prepared by sequential oxyanionic copolymerisation of styrene oxide followed by ethylene oxide (Fig. S1). The general method has been described in detail previously (Yang et al., 2003b) . Briefly, the difunctional initiator was potassium hydroxide and water. Freshly dried styrene oxide was transferred into the ampoule and heated at 85C for 8 weeks. Then ethylene oxide was distilled into the ampoule and kept at 65°C for about 3 weeks until polymerisation was completed. The copolymer was characterised by gel permeation chromatography (GPC, Agilent 1260 Infinity with triple detectors and two Agilent PLgel Mixed-D columns, tetrahydrofuran eluent, calibrated with poly(styrene) standards for measurement of molecular weight and polydispersity. 1 H and 13 C NMR spectroscopies (Bruker Avance 400, Bruker, Coventry, UK) were used to determine the composition of the copolymer (Figs. S2 andS3). The assignment for the peaks of ESE copolymers was made according to relevant references (Heatley et al., 1991) .

MPEG Gel permeation chromatography (GPC) was used to characterise the MPEG-DEN copolymers. The GPC system was an Agilent 1260 Infinity with triple detectors and two Agilent PLgel Mixed-D columns. Dichloromethane was used as eluent at a flow rate of 1ml min -1 . The system was calibrated with Agilent EasiVial PS-M and PS standards (M p 217,900).