Acyclic diene metathesis (ADMET) is a flexible approach for the production of diverse polymeric materials. The advent of well‐defined catalysts and the simplification of laboratory techniques has made the ADMET reaction useful for many applications, such as polyolefin model studies and the synthesis of organic/inorganic hybrid polymers, telechelics, copolymers, conjugated polymers, liquid crystalline polymers, and amino acid‐based chiral polymers. Many of the polymer architectures that have been produced using ADMET cannot be made by other means.
Three substituted unsaturated polycarbosilanes were prepared from the same parent using a two-step, one-pot ADMET polycondensation-nucleophilic substitution route. Condensation metathesis of di(4-pentenyl)dichlorosilane using Schrock's [Mo] catalyst produces a polymer backbone containing two reactive silicon-chlorine bonds per unit. Replacement of these bonds with stable alkyl moieties was performed using an excess of alkyllithium reagent without undesirable main chain alkylation or crosslinking. Upon functionalization, moisture-stable polymers were synthesized, indicating quantitative substitution was achieved. All of the resulting polymers are amorphous, elastomeric materials. Variation of the two pendant groups from phenyl to methyl resulted in a T g change of over 85°C.
It is now evident that ADMET chemistry can be employed to prepare a family of unsaturated carbosilane polymers containing a common backbone decorated with different alkoxysilane pendant groups, demonstrating the generality and potential utility of this chemistry. Four functionalized silicon containing dienes have been synthesized by nucleophilic substitution of the same parent diene monomer containing two reactive silicon‐chlorine bonds. These new α,ω‐diene monomers have been polymerized under ADMET conditions using the 2nd generation Grubbs's ruthenium catalyst, producing polymers with useful molecular weights. Variation of the pendant group results in differing chemical and physical properties of the resulting polymers. We believe this chemistry offers much to broaden the synthetic pathways to new organosilicon polymers.
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Mice selected by McClearn and Kakihana for differences in ethanol-induced sleep time were used as subjects. In Experiment 1, mice from the long-sleep (LS) and short-sleep (SS) lines were offered a choice of water or solution GS consisting of 3% glucose and .16% sodium saccharin (w/v); or a choice of water or solution GS + E that contained GS solution plus 4% ethanol (w/v). In Experiment 2, mice from the first experiment were provided with a three-way choice among water, solution GS, and solution GS + E. In both experiments, SS mice (alcohol-insensitive) consumed more GS + E than LS mice (alcoholsensitive). In addition, female mice drank considerably more GS + E solution than male mice. Thus, consumption of sweetened ethanol in both a two-way choice (water and GS + E) and a three-way choice (water, GS, and GS + E) is dependent on both genotype and sex. High genetic sensitivity to ethanol was associated with low consumption, and vice versa. Although females consumed more alcohol than males, females of these lines have not been previously found to show lower sensitivity to acute alcohol administration.
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