Hwiseok Jun, Trang Huyen Le Kim, Sang Woo Han, Mintae Seo

Supplementary Data

Polyglycerol-poly(-caprolactone) Block Copolymer as a New Semi-solid Polymeric Emulsifier to Stabilize O/W Nanoemulsions

Hwiseok Jun, Trang Huyen Le Kim, Sang Woo Han, Mintae Seo,

Jin Woong Kim, and Yoon Sung Nam

Synthetic procedures for PG-b-PCL

Synthesis of ethoxyethyl glycerol ether (EEGE, 1).

Briefly, 70.0 g (0.945 mol) of glycidol and 225.9 g (3.821 mol) of ethyl vinyl ether were introduced in a 500 mL three-neck flask. After magnetic stirring for 3 min, the mixture solution was cooled to – 30 °C. To the cold mixture solution was slowly added 0.75 g (3.94 mmol) of TsOH monohydrate, followed by magnetic stirring of the mixture solution at 25 °C. After 3 h, the mixture solution was added to 75 g of a saturated NaHCO3 solution (68 mL), and the product was extracted twice with ethyl acetate (84 mL  2). The organic layer was separated and dried with MgSO4. After filtration, the residual ethyl vinyl ether was removed under reduced pressure (65 cmHg) at 40 °C. The remainder was distilled in vacuum at 65 oC to yield ethoxyethyl glycerol ether (EEGE) as a colorless liquid product.

Polymerization of ethoxyethyl glycidyl ether (PEEGE, 2).

A 500 mL three-neck flask was dried by heating under a stream of nitrogen gas. A potassium tert-butoxide solution in anhydrous THF (6.75 ml, 3 M) was introduced to the dried flask under nitrogen environment. The reactor was cooled to – 50 °C, and EEGE (compound 1, 40 g) was added to the above solution. The temperature was slowly increased to 65 °C and then maintained at the same temperature during the polymerization process. After 24 h polymerization, the flask was cooled back to room temperature, and cold methanol (10 °C) was added to the reactor. The reaction was kept at room temperature for 2 h. The solvent was evaporated at 30 °C. The resulting polymer was dissolved in hexane and centrifuged at 3,500 rpm for 10 min to remove the precipitated potassium chloride, followed by drying in vacuum for 24 h.

Synthesis of PEEGE-b-PCL (3).

Twenty two grams (144.5 mmol) of PEEGE (compound 2, Mw = 3.7 kDa, determined by GPC) and 16.5 g of ε-caprolactone were introduced into a three-neck flask containing a teflon-coated magnetic stirring bar. The flask was degassed in vacuum and purged with argon gas flowing through a rubber septum. The mixture was melted in an oil bath pre-heated at 125 °C. Immediately, tin(II) 2-ethylhexanoate (1.15 g, 3 wt-% of PEEGE + -caprolactone) was introduced into the flask through the septum via gastight syringes. The reaction was conducted for 20 h at the same temperature, and the flask was cooled to room temperature. The resulting polymer was dissolved in 200 mL of methylene chloride and then centrifuged at 3,500 rpm for 10 min to remove undissolved impurities. After removal of methylene chloride using a rotary evaporator, the block copolymer was precipitated into a 10-fold excess of cold hexane. The precipitate was filtered through a glass filter, washed with hexane twice more, and then placed in reduced pressure to obtain dried samples.

Synthesis of PG-b-PCL (4).

Briefly, 8 g of PEEGE-b-PCL (compound 3) were dissolved in 50 g of acetone. An aqueous solution of 2.46 g of oxalic acid in 16.5 g of water was prepared. The oxalic acid solution was poured into the PEEGE-b-PCL solution, and the reaction pot was left at an ambient temperature with magnetic stirring for 5 h. After the reaction time, the mixture was dialyzed against an excess amount of water (MWCO = 1 kDa) at room temperature for 1 day. Water in the dialyzed product mixture was removed with a rotary evaporator at 75 °C for 40 min, and evaporation was repeated for three times with acetone to remove water azeotropically. 1H-NMR (ppm, 300 MHz, CDCl3): 1.37 (m, 2H); 1.63 (m, 4H); 2.30 (t, 2H); 3.41-3.78 (m, 2H); and 4.05 (t, 2H).

Table S1. Solubility of PG-b-PCL in water and organic solvents.

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Fig. S1 1H-NMR spectrum of PG-b-PCL block copolymer with peak assigments and areas.

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Fig. S2 Fluorescence spectra of pyrene with excitation at 332 nm at different concentrations of PG-b-PCL

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Fig. S3 Zeta potential values of PG-b-PCL micelle-like aggregates in water.

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Fig. S4 Chemical structures of three different oils that were used for this work.

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Fig. S5 Wetting properties of PG-b-PCL in ODO, CEH and DC345.