Polysiloxane 334 INDEX

The retention index of 657 for benzene on poly(dimethylsiloxane) in Table 24-3 means that benzene is eluted between hexane (7 = 600) and heptane (7 = 700) from this nonpolar station-aiy phase. Nitropropane is eluted just after heptane on the same column. As we go down the table, the stationary phases become more polar. For (biscyanopropyl)09(cyanopropylphenyl)0l-polysiloxane at the bottom of the table, benzene is eluted after decane, and nitropropane is eluted after -Cl4H30. 

In this chapter two different kinds of phase materials are presented the first is a chiral diamide selector bonded to a polysiloxane matrix the other selector system is a calix[4]arene with chiral residues which is attached to a polysiloxane backbone (Sect. 2.4). These systems were used in direct optical methods based on a change in the refractive index or the optical thickness of a transparent polymeric layer. 

Index Entries Lipase sol-gel matrix polysiloxane-polyvinyl alcohol esterification activity. 

High Refraction Index Polysiloxanes via Organometallic Routes - An Overview... 

Chem. Descrip. Polysiloxane sol n. in cyclohexanone Uses Defoamer tor org. systems incl. chlorinated rubber, vinyl resin, acrylic resin, alkyds, solvent-based coatings Properties Pale to It. yel. Iiq. ether-like odor sp.gr. 0.95 g/cc dens. 7.90 Ib/gal vapor pressure 4 mm Hg flash pt. (Seta) 43 C ref. index 1.450 0.7% NV... 

Temperature-programmed thermogravimetry in inert gas gives a quick survey of the evaporation behavior, as shown in Fig. 4-144 for some polysiloxanes. For comparison, the TGA curves of a polyalphaolefm (sample 1) and of a perfluoroalkylether (sample 29) are also plotted. Those substances evaporate at considerably lower temperatures than the polysiloxanes despite their substantially higher viscosities. Similar behavior was observed in the isothermal gravimetry. For comparison the oven-aged samples (120 days at 220 "C both with and without wood chips) were also tested by thermogravimetry. The index numbers from those experiments are listed in Table 4-185. 

Cetearyl methacrylate Synonyms Cetyl-stearyl methacrylate Uses Monomer for mfg. of polymers used as oil additives, vise, index improvers, pour pt. depressants internal plasticizer for adhesives, UV-curable resins, coatings Cetearyl methicone Synonyms C16-18 alkyl methicone Dehnition Alkyl modified polysiloxane fluid Uses Lubricant, spreading agent, moisturizer, emollient in protective skin prods., sun care... 

Prior to 1994, polysiloxanes prepared by hydrolytic polymerization of alkoxysilanes or halosilanes were indexed in CAS s CA File at the index heading Siloxanes and Silicones with no pol5mier registration. Polysiloxanes described by authors only in terms of SRUs were indexed at this heading with no polymer registration. [A description of the indexing enhancements is also available from CAS Customer Service and is offered on the world wide web (WWW) at http //www. cas. org/E 0/silox.html. ]... 

Popov et al measured the relative retention volumes and retention indices for silicon tetrachloride, methyltrichloro- and dimethyldichloro-silane, phosphorus trichloride and phosphorus oxychloride at 50 0 on the following stationary phases (each in a concentration of 20% on the support) Vaseline oil, polysiloxane liquids VKZh-94, PFMS-2 and DS-701 fluorosilicone oil 169, dinonyl phthalate and dibutyl phthalate. The retention index for phosphorus oxychloride increased with increase in the polarity of the stationary phase that for silicon tetrachloride remained practically constant. The maximum difference in retention volume was obtained on a nonpolar stationary phase for phosphorus trichloride and the chloro-silanes, and on a polar stationary phase for phosphorous oxychloride and the chlorosilanes. 

There are well defined maxima for the cyclic polymers in both plots at n == 22. No such maxima are shown by the chain molecules. As a results of the different bond angles at the silicon and oxygen atoms of the polysiloxane chain, a cyclic molecule with n = 22 can adopt a low energy conformation in the all-trans state. Consequently, the ring has a planar disc-sh ed character and such rings can pack more efficiently than spherical molecules, giving rise to the increase in density and refractive index. 

The filters were designed for operation at 530 nm, and preliminary estimates for monolayer thickness I and refractive index Wq for both materials were obtained by ellipsometry, reflectometry and waveguiding techniques (Table 3.2). Reasonable agreement was obtained between these techniques, particularly for the polysiloxane. The thickness and refractive index data were then refined to give more accurate initial layer thickness f and refractive index values (Table 3.3) by taking account of the dispersion of the materials over the wavelenth range 400-800 nm (Fig, 3.12). 

Fig. 3.12 Refractive index dispersion of polysiloxane and 22-tricosenoic acid (co-TA).

Fig. 3.14 Digitized refractive index profile of rugate filter constructed using polysiloxane and 22-tricosenoic acid (oj-TA).

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