POLY FLUOROSILICONES

The presence of carbon—fluorine bonds in organic polymers is known to characteristically impart polymer stabiUty and solvent resistance. The poly(fluorosibcones) are siloxane polymers with fluorinated organic substituents bonded to siUcon. Poly(fluorosibcones) have unique appHcations resulting from the combination provided by fluorine substitution into a siloxane polymer stmcture (see Silicon compounds, silicones). 

The incorporation of a singlecarbon—fluorine bond into a polymer cannot provide the stabiUty and solvent resistance offered by multiple bonds or clusters ofcarbon—fluorine bonds available with substituents like the CF, 2 5 3 7 Therefore, commercially interesting po1y(fluorosi1icones) 

When fluorine is beta to siUcon, compounds undergo a facile elimination of an ethylenic compound and again form the stable silicon—fluorine bond 

Stmctures with the widest temperature range of demonstrated stabiUty have fluorine in the gamma position relative to siUcon (or further removed), as in CF2CH2CH2SiIlR R. Longer hydrocarbon chains, with or without hetero atoms, are feasible, but oxidative stabiUty is compromised and such materials are generally disfavored. Poly(3,3,3-trifluoropropyl)methylsiloxane [26702-40-9] demonstrates this stmctural principle. This polymer is one key member of the industrially important family of fluorosiUcone materials. 

Low Temperature Properties. The property of solvent resistance makes fluorosihcone elastomers usefiil where alternative fluorocarbon elastomers cannot function. The abiHty to retract to 10% of their original extension after a 100% elongation at low temperature is an important test result. Eluorosihcones can typically pass this test down to —59°C. The brittle point is approximately —68°C. 

---

FLUORINECOMPOUNDS,ORGANIC - POLY(FLUOROSILICONES)] (Volll) Cyclotriveratrylene [1180-60-5]... 

Fluorosilicate glass-ceramics, 12 634-637 Fluorosilicates, 12 631 Fluorosilicone bases, 20 243 Fluorosilicone blends, 20 247 Fluorosilicone compounds, 20 243 Fluorosilicone rubber, 20 246—247 Fluorosilicones, 20 241 21 772. See also Poly(fluorosilicones)... 

Rubber crumb, 10 710 Rubber extrusion, 10 710 Rubber fabrication, of poly(fluorosilicones), 20 243-244... 

Rubber, poly(fluorosilicone), 20 246—247 Rubber, polychloroprene, 79 840 Rubber products, microwave technology in, 76 530... 

Fig. 6.16 NSE relaxation curves obtained from a 16% volume fraction poly(fluorosilicone) gel in acetone using tbe bigb resolution NSE spectrometer INI5 at tbe ILL, Grenoble. Tbe existence of plateaus that represent tbe level of excess scattering from static inhomogenieties at low wave vector Q is clearly visible. Tbe decay rates times of tbe dynamic parts yield tbe collective diffusion coefficient of tbe gel. (Reprinted with permission from [291]. Copyright 2002 American Chemical Society)...

---