Cyclooctane polymer

Bis(bexacbIorocycIopentadieno)cycIooctane. The di-Diels-Alder adduct of hexachlorocyclopentadiene [77 7 ] and cyclooctadiene (44) is a flame retardant having unusually good thermal stabiUty for a chlotinated aUphatic. In fact, this compound is comparable ia thermal stabiUty to brominated aromatics ia some appHcations. Bis(hexachlorocyclopentadieno)cyclooctane is usedia several polymers, especially polyamides (45) and polyolefins (46) for wire and cable appHcations. Its principal drawback is the relatively high use levels required compared to some brominated flame retardants. 

Srinivasan and Ford [158] reported that epoxidation of cyclooctene using excess H202 was catalyzed by polymolybdate such as [Mo7024]6 tethered on the colloidal polymer with alkylammo-nium cations. Cyclooctene was oxidized to give 1,2-epoxy cyclooctane with >99% selectivity at 90% conversion for 24 h at 313 k ... 

We have a dilemma we need a high-quality solvent to insure that the polymer remains in solution when it is formed but we need a solvent whose quality can be easily adjusted to induce the polymer to drop out of solution. How can we resolve it First, we need to know the thermodynamic variables that cause the occurrence of an LCST (chapter 3). The key variable in this instance is the chemical nature of the solvent or, to a first approximation, the critical properties of the solvent. Decreasing the solvent quality shifts the LCST curve to lower temperatures, and it is this variable that we wish to manipulate to force the polymer out of solution. To demonstrate the effect of solvent quality on the location of the LCST curve, consider the difference in LCST behavior for the same polymer, polyisobutylene, in two different solvents, n-pentane and cyclooctane. The LCST curve for the polyisobutylene-rt-pentane system begins at 70°C, while for the polyisobutylene-cyclooctane system it begins at 300°C (Bardin and Patterson, 1969). Cyclooctane, which has a critical temperature near 300°C, is a much better solvent than n-pentane, which has a critical temperature near 200°C, probably because cyclooctane has a greater cohesive energy density that translates into a lower thermal expansion coefficient, or equivalently, a lower free volume. Numerous examples of LCST behavior of polymer-solvent mixtures are available in the literature, demonstrating the effect of solvent quality on the location of the LCST (Freeman and Rowlinson, 1960 Baker et al., 1966 Zeman and Patterson, 1972 Zeman et al., 1972 Allen and Baker, 1965 Saeki et al., 1973, 1974 Cowie and McEwen, 1974). 

Thus the most reactive (i.e., thermodynamically least stable) monomers are those containing 3- or 4-membered rings. The data in Table 10.1 further show that cyclohexane is the most resistant to polymerization, since AG is positive. For cyclopropane, cyclobutane, cyclopentane, cycloheptane, and cyclooctane, AG for polymerization is negative, indicating that the polymerization is feasible. However, thermodynamic feasibility does not always guarantee realization in practice and no high polymers of cyclopropane and cyclobutane are known (Sawada, 1976). 

Ru(r -C8Hio)(7] -C8Hi2) reacts rapidly with dihydrogen (1-3 atm) at room temperature in a hydrocarbon solvent to give ruthenium particles and cyclooctane. In the presence of a polymer (PVP nitrocellulose, NC cellulose acetate, CA), the reaction produces particles, the size of which depends upon the nature of the polymer and upon the relative concentration of the precursor in the polymer. In this way, monodisperse particles of 1 to 1.5 nm mean size have been... 

Wu, J. McKenna, G. B., Anomalous Melting behavior of Cyclohexane and Cyclooctane in Poly(dimethylsiloxane) Precursors and Model Networks. J. Polym. Set. PartB Polym. Phys. 2008,46, 2779-2791. 

Anthracene and its derivatives undergo a [4-F4] photocycloaddition to cyclooctane-containing dimers. This reaction can be reversed with mechanical forces, 3delding fluorescent anthracenes. Poly(vinyl alcohol) was crosslinked with anthracene dimers to give polymers that could report microcracks in a similar way as the tricinnamate-containing polymers described above (Figure 11.3). 

The synthesis procedure (Scheme 31.1) was developed originally using as precursor [Ru(COD)(COD)] as precursor and dihydrogen as reducing agent in the presence of a polymer, namely, nitrocellulose (NC), cellulose acetate (CA), or poly(vinylpyrrolidone) (PVP) under mild conditions (3 bar H2, room temperature). The hydrogen treatment allows the reduction of the olefln ligands into cyclooctane, which is inert toward the metal surface. These NPs are stable and can be used for surface reactivity studies. With PVP, very small (1.1 nm) NPs wCTe obtained (Fig. 31.1) [16]. 

Experimental conditions Ru cat. (0.03 mmol). PhCl (5 mL), cyclooctene (7.5 mmol). 2 h at 60°C TDetermined by GC using cyclooctane as internal standard l>etermined by size-exclusion chromatogr hy in THE with polystyrene calibration Fraction of cis double bonds in the polymer, determined by C NMR spectroscopy. 

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