Emulsion polymerization, acrylic core-shell compositions

Figure 18 Schematic representation of the preparation of Ag SPEB(PS-PAA) composite particles in situ. PS core particles are first prepared by a conventional emulsion polymerization. In the second step, the PS cores are covered with a thin layer of photoinitiator HMEM. In the third step, the shell of polyelectrolyte brushes is formed by photoemulsion polymerization Shining light on the aqueous suspension of these particles generates radicals at their surface, which initiate the radical polymerization of the functional monomer (silver acrylate) on the surface of the core particles. Concomitantly, the silver anions embedded in the PAA brushes are reduced to Ag-NP under UV irradiation. Reprinted with permission from Lu, Y. Mei, Y. Schrinner, M. etal.

Shaffer et al [365] have continued to modify staining techniques for TEM of latex particles. Recent work on structured latex particles prepared by seeded emulsion polymerization focused on the effects of changes in polymerization variables, such as batch versus semicontinuous, core-shell ratio, shell thickness and shell composition. In this system the core was poly(n-butyl acrylate) and the shell was poly(benzyl methacrylate-styrene). A few drops of the latex was combined with a few drops of a 2% uranyl acetate solution which serves as a negative stain. A drop of that mixture was deposited on a stainless steel formvar-coated grid. After drying it was stained in ruthenium tetroxide vapor to differentiate the rubbery core, which is not... 

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