Fluorosilicone PTFPMS

Surface tension studies of the most common fluorosilicone, poly(3,3,3-trifluoropropylmethylsiloxane) (PTFPMS), give unexpected results. Compared with (PDMS), PTFPMS has a higher liquid surface tension, a similar critical surface tension of wetting, and a considerably lower solid surface tension, as determined by water and methylene iodide contact angles and the method of Owens and Wendt (67). These results are summarized in Table X (7, 67, 72-74, 76, 77), in which PTFPMS is compared with two other fluorocarbon polymers, poly(tetrafluoroethylene) (PTFE) and poly(chlorotrifluoroethylene) (PCTFE). PTFE behaves like PTFPMS, whereas PCTFE behaves like PDMS. 

Fluorosilicone materials have always had the potential of being amongst the lowest known surface energy materials because they combine the low intermolecular forces between aliphatic fluorocarbons with the high flexibility of the siloxane backbone. Historically, commercial emphasis was on minimally fluorinated fluorosilicones such as poly (3,3,3-trifluoropropyl) methylsiloxane (PTFPMS) and it is only recently that more highly fluorinated materials have become available and this potential realized. ... 

The Tg of the PTFPMS ranges from -75 to -65 °C and, unlike PDMS, it does not exhibit low-temperature crystallization at -40 °C. This is because of the inability of the polymeric chain to pack into a crystalline lattice [3]. It can be cross-linkable from various classical processes of the chemistry of silicones such as in the presence of peroxides or from the SiH/Si-CH=CH2 systems [12]. However, the relatively low strength limits the use of fluorosilicones to static applications such as seals for fuel lines [3]. 

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