Chemistry Reference
In-Depth Information
and interfaces (e.g., as water repellents, antifoaming agents, and mold-re-
lease agents). In some cases the polysiloxane is blended into a material to
improve its mechanical properties (e.g., its impact strength). For such ap-
plications, finely divided cross-linked powders are available commer-
cia l ly.
17-18
Two additional examples are the uses of polysiloxanes in
polymer-electrolyte complexes
19
and in microlithographic applications.
20
Figure 10.4 shows a typical nonmedical application of a siloxane poly-
mer. In this case, a liquid, UV-curable polysiloxane is being used to protect
a printed circuit board. The polymer being used was specifically chosen for
its low viscosity, moisture resistance, and easy repairability. Also, some
such materials can be treated so that thin spots in the coating are readily
apparent. Although dip coating is illustrated in the figure, flow coating
and spray coating can also be used.
One of the most impressive applications of polysiloxanes, particularly
in the arts, is their use in making molds of intricate surfaces (figure 10.5).
In this case, the surface to be copied was vertical and nonmovable, so a
Figure 10.4:
An electronic circuit board being given a protective polysiloxane coating. The photograph
was provided by the Dow Corning Corporation of Midland, MI.
