A series of poly(glycerol monomethacrylate-block-2-hydroxypropyl methacrylate-block-benzyl methacrylate) framboidal triblock copolymer vesicles (denoted as G63-H350-Bz for brevity; where the mean degree of polymerization of the third block, z, is systematically varied from 21 to 373) were prepared via RAFT seeded emulsion polymerization of benzyl methacrylate using a linear G58-H300 vesicle precursor. These framboidal vesicles were characterized using TEM, DLS and small-angle x-ray scattering (SAXS) and then evaluated as Pickering emulsifiers for the stabilization of n-dodecane droplets in water. When z exceeds 125, increasing the aqueous vesicle concentration led to a monotonic reduction in the mean droplet diameter until a limiting value of ~ 60 �m was attained at ~ 2.0% w/v. This concentration dependence indicates that the additional hydrophobic character conferred by the poly(benzyl methacrylate) block is sufficient to stabilize the vesicles during high shear, allowing adsorption at the oil/water interface as intact vesicles. A turbidimetry assay was used to determine the vesicle adsorption efficiency as a function of increasing surface roughness. The adsorption efficiency increased from 17 % up to 90 % when z was increased from 21 to 125, but remained relatively constant at higher z values. Hence there is a strong positive correlation between surface roughness and Pickering adsorption efficiency. Moreover, this represents a significant improvement in Pickering emulsifier efficiency compared to that reported previously for non-framboidal cross-linked copolymer vesicles [J. Am. Chem. Soc., 2012  , 134, 12450].

Framboidal triblock copolymer vesicles: A new class of efficient Pickering emulsifier

248th National Meeting (2014)

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