Original Entry: Tom Dimiduk APPHY 225 Fall 2010
[High-Yield Synthesis of Monodisperse Dumbbell-Shaped Polymer Nanoparticles http://pubs.acs.org.ezp-prod1.hul.harvard.edu/doi/pdf/10.1021/ja101760q]
Surface Tension, Janus Colloid, Polymerization, Asymmetry, Core-shell Particle
Figure 1: The authors' synthesis process, (a) schematic representation showing particle, adding the core, swelling, and then new polymerization to form the dumbell. (b) Electron micrograph of the polystyrene nanoparticles, (c) the core shell nanoparticles, (d) the symmetric dumbell particles.
Figure 2: Demonstration of the effects of toluene on the core shell particles. (a) the polystryene particles take up toluene and cream at the top when centrifuged, the copolymer and core shells do not take up enough toluene to rise. (b) electron micrograph showing deformation caused by toluene swelling in the core shell particles.
Figure 3: Changing the relative size of the two dumbell portions by varying ratio of swelling monemer to seed particles. (a) 1.3, (b) 1.6, (c) 2.0, and (d) 3.0. (e) shows where the measurments plotted in (f) are taken.
File:Dufresne dumbell fig4.png
Figure 4: Electron micrographs of the structures these particles assemble into. Scale bar in (a) is 5 micron, others are 1 micron
The authors present a high yield, scalable method for synthesis of asymmetric nanoparticles with aspect ratios of up to 1.8. They use core shell particle consisting of a polystyrene core with a random copolymer of styrene and trimethoxysilylpropylacrylate (TMSPA) grown on the outside as a shell. The polystyrene can be swelled with toluene or styrene monomer. At sufficiently high swelling, the core will breach through the copolymer shell (see figure 1 and 2).
Soft Matter Discussion