Network PFCB fluorosilicones

PFCB Fluorosilicone Networks 4 -6 With the exception of TFVE terminated copolymer 4f, upon heating TFVE functionalized copolymers 4-6 in aluminum pans at 165°C for 6-24 h, tack-free transparent free-stending films of fluorosilicones 4 -6 were obtained (Figure 8). TFVE terminated copolymer 4f underwent substantial chain extension as characterized by a dramatic increase in viscosity yet remained completely soluble in common solvents. 

Figure 8. PFCB Fluorosilicone Networks from Mono-olefin Derived Copolymers.

For the most part, PFCB fluorosilicones were generally stable below 400°C and glass transition temperatures remained remarkably low despite relatively high levels of crosslinking. A detailed thermal property comparison between the reactive precursor polymers and the corresponding networks is currently underway. 

PFCB Fluorosilicone Networks As similarly found for the thermal... 

Table 5. Selected Thermal Properties of PFCB Fluorosilicone Networks.

PFCB silicone networks are distinguished from typical commercial fluorosilicones since catalysts or initiators are not required and crosslinking occurs exclusively at the fluorocarbon sites. In most cases, the crosslinked polymer films could be easily peeled from the aluminum surface. The films exhibited considerable swelling in organic solvents and FTIR confirmed the distinct presence of the hexafluorocylclobutane linkage at 963 cm". Some thermal properties are summarized in Table 3. 

---