Fluorosilicone liquid surface tensions

The high values for the trifiuoropropyl group are surprising but correspond with the liquid surface tension of polytrifluoropropylmethylsiloxane [13], although not in line with its critical surface tension and solid surface tension. The low values for the longer fluoroalkyl groups are comparable to the lowest surface tension fluoropolymers and correspond well with the values for related preformed fluorosilicone polymers [14-15]. 

Table VIII. Liquid Surface Tension (criv) of Fluorosilicones at 20...

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. 

FIGURE 9.3 Liquid surface tensions of fluorosilicones as a function of fluorocarbon side-chain length (solid diamond 7000 open triangle 20-30,000 open star copolymer of PMTFPS and PDMS). Reprinted with permission from Reference 2. Copyright 2012 Springer Science-I-Business Media B.V. 

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