Experimental SectionMeasurements. 1 H NMR (500 MHz) spectra were acquired in CDCl 3 using a Varian INOVA-500 spectrometer at 25 °C. Tetramethylsilane (TMS) was used as an internal reference for 1 H NMR spectroscopy. FT-IR spectra were obtained on a Bruker Tensor 27 system using attenuated total reflectance (ATR) sampling accessories. High resolution mass spectrum was obtained on a ThermoFinnigan MAT XL spectrometer.Matrix-assisted laser desorption/ionization time-of-flight mass spectrometery (MALDI-TOF) was measured on a Bruker Biflex IV (Billerica, MA) MALDI mass spectrometer equipped with a nitrogen laser (λ = 337 nm). Mass spectrum was acquired in the reflection mode with a mass range of 2000-12000 m/z, and the mass scale was calibrated externally using the peaks of peptide calibration standard II purchased from Bruker. Trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenylidene]malononitrile (DCTB, Aldrich; ≥99%) served as matrix and was dissolved in CHCl 3 at a concentration of 20 mg/mL. Sodium trifluoroacetate (NaTFA, Aldrich; ~98%) served as cationizing agent and was dissolved in MeOH/CHCl 3 (1/3, v/v) at a concentration of 10 mg/mL. The polymer was dissolved in CHCl 3 at a concentration of 10 mg/mL. The matrix solution, polymer solution, and NaTFA solution were mixed in the ratio of 10/1/1 (v/v/v). The sample preparation involved depositing 1 μL of the mixture on the steel plate, and allowing the spot to dry.Gel permeation chromatography (GPC) was conducted using Viscotek GPC system equipped with a VE-3580 refractive index (RI) detector, a 270 dual detector system having a viscometer detector and a dual-angle (7 º and 90 º) laser light scattering (LS) detector, a VE 1122 pump, and two mixed-bed organic columns (PAS-103M with exclusion limit of 70 kDa and PAS-105M with exclusion limit of 4 MDa). N,N'-dimethylformamide (HPLC grade) with 0.1 M

Amphiphilic double-brush copolymers (DBCs) with each graft site quantitatively carrying both a hydrophilic poly(ethylene oxide) (PEO) graft and a hydrophobic polylactide (PLA) graft were synthesized, characterized, and further utilized as surfactants for the stabilization of miniemulsions. Well-defined PEO-b-PLA-based diblock macromonomers (MMs) with exo-norbornene (NB)-functionalized diblock junction were prepared by the synthesis of a PEO-based NB-functionalized alcohol via polymeric reaction, followed by ringopening polymerization (ROP) of lactide (LA) initiated by the alcohol. Ring-opening metathesis polymerization (ROMP) of the MMs yielded DBCs. The well-controlled structures of the MMs and the DBCs were verified through rigorous instrumental characterizations. As compared with the MMs, the corresponding DBCs had lower crystallinities and melting temperatures (T m s) for both PEO and PLA phases and showed a negligible tendency for intermolecular self-assembly in solutions. With nanoscopic dimensions and novel amphiphilic architectures, these DBCs represent a new type of giant polymeric surfactant. Relative to the precursor MMs, the DBCs resulted in miniemulsions with remarkably enhanced stability.

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