Polytetrafluoroethylene spheres

In addition to the standard model systems described above, more exotic particles have been prepared with certain unusual properties, of which we will mention a few. For instance, using seeded growth techniques, particles have been developed with a silica shell which sttrrotmds a core of a different composition, such as particles with magnetic [12], fluorescent [13] or gold cores [14]. Another example is that of spheres of polytetrafluoroethylene (PTFE), which are optically anisotropic because the core is crystalline [15]. 

Fillers/reinforcements can be used to increase the thermal conductivity of the material such as glass and metal fibers or spheres. The filter can be a material like PTFE (polytetrafluoroethylene) plastic that has a much lower coefficient of fnction and the surface exposed material will reduce the fiiction. 

Figure 10.2 Normalized tracer rotational diffusion coefficients. (+) 113 nm silica probe spheres in a matrix suspension of 123 nm matrix spheres in dimethylformamide dimethylsulfoxide obtained using TPA(41). Colloidal 100 nm polytetrafluoroethylene-polyperfiuoromethylvinylether spheres in 18% urea 0.1 M NaCl water studied with DDLS by (x) Degiorgio, et al. (10) and by Piazza and Degiorgio(40) using (Q) DDLS and (0) FDDLS.

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