Poly raspberry-like particles

Fig. 6 Left Elaboration of silica/polystyrene raspberry-like colloids through emulsion polymerization using a MMA-terminated poly(ethylene oxide) macromonomer (PEGMA) as coupling agent. Right SEM and TEM pictures of the raspberry-like particles. Adapted from [40] with permission of American Chemical Society...

Microscopic observations revealed that polymer formed during the above-mentioned process was shaped into the raspberry-like particles (see Figure 2). The diameters of particles formed in the absence of poly( ethylene oxide) were in the range of 25-100 jm, whereas the diameters of particles formed by polymerization in the presence of poly(ethylene oxide) (samples with Mn equal to 15 000 and 40 000 were used in the studies)... 

Li et al. [51] prepared monodisperse microspheres by distillation precipitation polymerization of DVB and NIPAM with 2,2-azobisisobutyronitrile (AIBN) as initiator in acetonitrile, in the absence of any surfactant. Next, latex particles of poly(EGDMA-co-AA) were assembled onto the microspheres to afford a corecorona composite polymer particle with a raspberry-like morphology, strengthened by hydrogen-bonding interaction. 

Of relevance to this section, Reculusa et al. also recently demonstrated that the addition of a small amount (only 1.5 pmole/m ) of a monomethylether mono methylmethacrylate poly(ethylene oxide) macromonomer (structure 9, Table 4.5) allowed the direct self-assembly of nanometric polystyrene latex particles on the surface of submicronic sihca particles through an in-situ nucleation and growth process (Fig. 4.12) [102]. The two sets of particles were assembled in a raspberry-like morphology via the formation of hydrogen bonds at the interface of the inorganic and organic coUoids. The size and shape of the assembly can be easily controlled by varying the sizes and stoichiometries of the colloidal components (Fig. 4.13). 

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