Fluorosilicon with

Furthermore, important and interesting investigations have been performed by Kobayashi and Owen [397] who prepared fluorosilicones with perfluorinated lateral group ... 

Furukawa et al. [21] examined a new synthetic method for fluorosilicones with a high content of fluoroalkyl side chains based on the hydrosilylation of fluorinated olefins with PHMS. They introduced perfluoro-octyl groups into silicone polymers in one step without using the cracking process usually used in the conventional method. Employing the same methodology, Furukawa et al. [22] prepared a series of fluorosilicone homopolymers with... 

Scheme 6.7 Synthesis of fluorosilicones with long chain fluoroalkyloxypropyl group substitution. Taken from Ref. [28],...

Y. Furukawa, T. Yoneda, Synthesis and properties of fluorosilicone with perfluoroocty-lundecyl side chains, J. Pol. Sci. Part A Pol. Chem. 41 (17) (2003) 2704-2714. 

The principal intent of this chapter is to compare and contrast the properties of this most common fluorosilicone with those of PDMS, the predominant polymer of... 

Fluorinated organosilicones are useful lubricants for rubber surfaces [190]. Fluorosilicones with a favorable fluoroalkyl chain length and siloxane chain-length ratio are effective lubricants and reduce the friction coefficient of liquid paraffin [191]. 

Whilst exhibiting the excellent low-temperature flexibility (with a Tg of about -80°C) and very good heat resistance (up to 200°C) typical of a silicone rubber, the fluorosilicones also exhibit good aliphatic oil resistance and excellent aging resistance. However, for some applications they have recently encountered a challenge from the polyphosphazenes (see Section 13.10). 

Fluorosilicones consist of PDMS backbones with some degree of fluoro-aliphatic side chains. The fluorinated group can be trifluoropropyl, nonafluorohexylmethyl, or fluorinated ether side group [78,28,79]. These polymers differ not only in substituent group, but also in the amount of fluoro-substitution relative to PDMS, the overall molecular weight and crosslink density, and the amount of branching. In most commercially available cases, these polymers are addition cure systems and the reactions are those discussed previously for silicone networks. 

The submitters used a 2.1 m. x 0.64 cm. column with 5% fluorosilicone (FS-1265) supported on Diatoport S as stationary phase. With a column temperature of 170° and a helium flow rate of 60 ml. per minute, 2-ethoxypyrrolin-5-one has a retention time of 2.2 minutes. The analysis was carried out at 160° by the checkers, using a column of 5% diethylene glycol succinate-Bentone supported on Diatoport S. The starting material had a retention time of 3.9 minutes under these conditions. Bentone is available from Applied Sciences Laboratory, Box 440, State College, Pennsylvania 16801. 

Based on the extensive work, Ghosh and De have concluded that fluoroelastomer and silicone mbber form technologically compatible blends of micro-heterogeneous stmcture with thermal stability between those for the blend components. The blend could be used as a replacement for fluorosilicone mbber. 

Mascia, L., Pak, S.H., and Caporiccio, G. Properties Enhancement of Fluorosilicone Elastomers with Compatibilized Crystalline Vinylidene Fluoride Polymers, Eur. Polym. J. 31(5), 459 65, 1995. 

Fluoroelastomers Novikova et al. [32] reported unproved physico-mechanical properties of fluoro mbbers by reinforcement with chopped polyamide fibers. Other fiber reinforcements are covered by Grinblat et al. [33]. Watson and Francis [34] described the use of aramid (Kevlar) as short fiber reinforcement for vulcanized fluoroelastomer along with polychloroprene mbber and a co-polyester TPE in terms of improvement in the wear properties of the composites. Rubber diaphragms, made up of fluorosilicone mbbers, can be reinforced using aramid fiber in order to impart better mechanical properties to the composite, though surface modification of the fiber is needed to improve the adhesion between fluorosUicone mbber and the fiber [35]. Bhattacharya et al. [36] studied the crack growth resistance of fluoroelastomer vulcanizates filled with Kevlar fiber. 

The checkers used a 40-cm. spinning-band column. The product, n2bD 1.4237, was shown to be 98.9% pure by gas-liquid chromatography on a 6-ft. 20% fluorosilicone column. The retention time was 3.75 minutes with a flow rate of helium of 100 ml. per minute, and a column temperature of 125° with the injection port at 170°. The 19 F n.m.r. spectrum (56.4 MHz) consists of four lines of equal intensity centered at +3396 Hz from trichlorofluoromethane (internal) and two sets of two overlapping quartets centered at +4369 Hz and +4461 Hz, respectively. The integrated intensities of the three sets of fluorine resonances are 3 1 1. 

The use of silicone elastomers for high-voltage applications (insulators and cable accessories) requires special formulations. Unusually, stringent requirements for these materials must be met.509,510 Fluorosilicone rubbers, which offer some unique combinations of properties (e.g., chemical resistance and higher temperature stability), have attracted considerable attention and have been reviewed in recent publications.511,512 It was noted that a modification of perfluoroether elastomers with silicone elastomer via hydrosilylation reaction opens the possibility of novel applications.5... 

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)...

It is noteworthy that this formulation is different from fluorosilicones. Fluorosili-cones are fluorine-containing silicone oils with a 1.35 g/cm density. Their poor tolerance in animals and men was demonstrated by experimental studies [45,46] ocular hypertonia, keratopathy, early emulsification and severe inflammatory reactions. They cannot therefore be used as a heavy internal tamponade product. 

M. Doi, M.F. Refojo, Flistopathology of rabbit eyes with silicone-fluorosilicone copolymer oil as six months internal retinal tamponade, Exp. Eye Res. 61 (1995) 469-478. 

Various gaseous (F-propane, SFe) and liquid (F-octane, F-decalin, F-perhydrophe-nanthren, mixed fluorocarbon-hydrocarbon diblocks, and fluorosilicones) F-com-pounds are being used as intraocular tamponades for use in vitreoretinal surgery [Chapter 9 by Rico-Lattes et a ., this volume]. Polymers with F-alkyl moieties are used in corneal inlays and implants and in intraocular lenses. 

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