Methylene chloride, solubility behavior

The effect of the moisture level in the eluent on the retention behavior is most pronounced with the least polar solvents, such as the hydrocarbons, in which water has a very limited solubility, usually less than 100 ppm. Conversely, the greater the solubility of water in the organic solvent is, the smaller the effect. For example, the water content of methylene chloride may vary by several parts per million without appreciably changing the k values as the solubility of water in CHtCIt is about 0.2%. 

Such drastic changes in selectivity may also occur with eluents pre-l lllCll imiii Iwti Qolvnila uf similiii elution slrmalh, such dichlor(>-methane and ethyl acetate. In Fig. 6 the effect of ethyl aceta concentration in dichloromethane on the retention behavior of some (steroids and barbiturates is illustialed (/). The k values of the sleRiids ate reduced drastically by the addition of 1% of ethyl acetate to methylene chloride. Some barbiturates behave similarly, whereas the behavior of others is dominated by other solvent effects that also manifest themselves in the widely different solubilities of the substances in methylene chloride and ethyl acetate. j... 

Solubility behavior of the copolymers in methylene chloride was examined by preparing a 103 solution in warm methylene chloride and allowing the solution to stand for two days at room temperature. The precipitate, if any, was filtered off under nitrogen pressure using a 0.45/t Millipore filter, washed with cold methylene chloride, and dried under vacuum. The soluble fraction was recovered by precipitation with methanol. A similar procedure was followed with m-xylene a 10% solution of the copolymer was heated overnight on a steam bath, the precipitate filtered off, dissolved in chloroform, and reprecipitated with methanol. 

Solubility in Methylene Chloride. The methods described above can show the presence of blocks of DMP and blocks of DPP units, but they do not distinguish between block copolymers and blends of homopolymers. Gel permeation chromatograms of the copolymers are sharp and symmetrical, indicating that they are indeed copolymers rather than blends, but this alone is not conclusive as blends of the homopolymers do not produce binodal or badly skewed curves under the conditions used unless the two polymers differ considerably in molecular weight. A partial answer to this question is provided by the solubility behavior in methylene chloride. Dimethylphenol homopolymer dissolves readily in methylene chloride but precipitates quantitatively on standing for a short... 

Solvent extraction is a technique that can be used to evaluate the curing behavior of photopolymers and as a measure of sol fraction. The method is dependent, on the solubility of the unreacted or partially reacted components in the chosen solvent (methylene chloride). The method yields the percentage of unreacted monomers and partially reacted low molecular weight components in the cured film. This is derived from the weight differential of the film before and after extraction. 

The electrochemical behavior of poly(RCOT)s has also been examined [40]. As expected from the electrochemical properties of unsubstituted polyacetylene, films of poly(RCOT)s coated on an electrode and immersed in an acetonitrile electrolyte solution (in which the polymers are not soluble) are found to undergo reversible oxidative and reductive doping. Unlike unsubstituted polyacetylene, these films may be prepared readily by casting from solution, or, in the case of poly(scc-butylCOT), by electrodecomposition from a THF solution. In contrast to the voltammetry of polymer films, cyclic voltammograms of methylene chloride... 

Metal-containing poly-yne polymers with molecular weight (Mw) of ca 1.2 xlO were soluble in usual organic solvents such as benzene, methylene chloride, tetrahydrofuran etc. The thermal stability of the polymers was increased with the metals, in the order of Pt > Pd >Ni. Films with a thickness of several microns and with a tensile strength as large as 9.0 X 10 g/mm were fabricated from the Pt-containing polymer. One of the characteristics of these polymers is their lyotropic liquid crystal behavior in solution. Some representative polymers prepared are listed in Table 15. 

Asphaltenes clearly consist of a distribution of molecular weights, types, and polarity, which can be conveniently subdivided according to their solubility behavior in mixtiues of a good solvent (e.g., toluene or methylene chloride) and a poor or nonsolvent (e.g., heptane). The most polar or least soluble fraction of asphaltenes (as gaged by this solvent—non-solvent fractionation method) appears to form the strongest interfacial films, all other thermodynamic parameters being equal. 

Polycarbonate s high toughness is based on its relaxation potential at low temperatures. Any accumulation of foreign molecules in individual chain segments influences relaxation capability and thus viscoelastic behavior. For example, methylene chloride or chloroform accumulates on the carbonate group, which is the reason for polycarbonate s good solubility in these media. 

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