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The dynamic behaviors of methylcyclohexane (MCH) and perfluoro(methylcyc1ohexane) (PFMCH) liquids confined to porous silica glasses prepared by the sol-gel process are compared. The NMR spin-lattice relaxation times, T I , of the MCH and PFMCH liquids in porous silica glasses are reported as a function of pore size in the range from 24 to 96 A over the temperature range from -8 to 45 "C. The pore-size-dependent experimental TI data are analyzed in terms of a general expression obtained from our previous studies, UT1 = 1/Tlb + B/R + A/R*, where T l b is the relaxation time for bulk liquid, R is the average pore radius, and A and B are two parameters which indicate the relative strength of surface and topological effects on the observed NMR relaxation rates of confined liquids. On the basis of the surface enhancement values, TldTl,, where TI, is the relaxation time of the surface layer liquid, we conclude that the confined PFMCH molecules have a stronger interaction with the glass surface and thus exhibit more hindered molecular motions than the confined MCH molecules. In contrast, topological confinement plays a smaller role in affecting the translational diffusion of PFMCH molecules near the glass surface. In addition to the confinement studies, we have investigated the dynamic structure of bulk PFMCH by analyzing shear viscosity data in terms of the rough-hard-sphere model of liquids in a manner similar to our previous bulk liquid MCH study.

SynopsisDilute solution properties of polyoctenel have been measured by light scattering, mmometry, and viscometry and Mark-Houwink expressions determined in two thermodynamically good solvents and one solvent at the Flory (8) temperature. The data have been interrelated and analyzed by the Kurata-Stockmayer technique and are shown to have good correspondence with the theory in some cmea and moderately poor in others.However, the data are not sufficiently precise to permit all aspects of the adequacy of such a two-parameter theory to be judged. EXPERIMENTALThe sample of polyoctene-1 was generously provided by Union Carbide Chemicals Company and was prepared with a Ziegler-type catalyst.When received, the sample was a yellow, tacky, rubbery material. PnrifIeation and FractionationBefore prepurification of the bulk polymer, one fractionation was performed by the standard technique of solventnonsolvent pair (cyclohexane-acetone, respectively) precipitation at constant temperature 3963

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