Syntheses of poly(9,9-dialkylfluorene-2,7-vinylene)s (PFVs, alkyl=n-hexyl, n-octyl, 2 0 -ethylhexyl) and poly(N-alkylcarbazole-2,7-vinylene)s (PCVs, alkyl = n-octyl, 9 0 -heptadecanyl) by acyclic diene metathesis (ADMET) polymerization using Ru-carbene complexes have been explored. The polymerizations in the presence of Ru(CHPh)(Cl) 2 (IMesH 2 )(PCy 3 ) and Ru(CH-2-O i Pr-C 6 H 4 )(Cl) 2 (IMesH 2 ) [Cy= cyclohexyl, IMesH 2 =1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene] afforded relatively high molecular weight PFVs, PCV (alkyl=9 0 -heptadecanyl) with unimodal molecular weight distributions, and the olefinic double bonds in the resultant polymers possessed highly trans regularity in all cases. The resultant defect-free PFVs possessed higher absolute quantum yields (Φ=92-99%) than those reported previously, whereas no significant differences in the UV-vis and the fluorescent spectra (absorption bands, peak maxima) in the resultant PFVs were observed as an effect of alkyl side chain in the 9-position. The UV-vis and the fluorescence spectra in the PCV were similar to those in the PFVs, indicating that the replacement (from fluorene to carbazole) does not affect the observed spectra; the resultant PCV also possessed remarkable absolute quantum yield (Φ=86%).

Facile, exclusive end functionalization of poly(9,9-di-n-octylfluorene-2,7-vinylene) (PFV), prepared by acyclic diene metathesis polymerization using Ru(CHPh)(Cl) 2 (IMesH 2 )(PCy 3 ) [IMesH 2 ) 1,3-bis(2,4,6trimethylphenyl)-2-imidazolidinylidene], has been achieved by treating the vinyl groups in PFV chain ends with Mo(CHCMe 2 Ph)(N-2,6-Me 2 C 6 H 3 )[OCMe(CF 3 ) 2 ] 2 followed by Wittig-type cleavage with 4-Me 3 SiOC 6 H 4 CHO; precise synthesis of ABA type amphiphilic triblock copolymers has been accomplished by grafting PEG into both the PFV chain ends.

No abstract

As a first step toward describing water flow processes in bedrock, we determined the hydraulic properties of three trimmed samples of weathered granitic bedrock (referred to as Samples A, B, and C, in order of size) in the laboratory. Silicone rubber was used to fill the space between each sample and the surrounding cylinder wall, ensuring accurate measurement of hydraulic properties of the samples. All samples showed similar saturated hydraulic conductivity values of 1 3 10 24 cm s 21 , with the saturated water flow in all samples obeying Darcy's Law. Unsaturated hydraulic conductivity and water retention functions of Sample A were determined by means of a multistep outflow experiment. Parameters in both functions were optimized by comparing observed and computed cumulative outflow rates. The resulting computed cumulative outflow rates using the optimized parameters showed a good match to the observed cumulative outflow data. Moreover, the derived water retention function agreed closely with the function measured by the pressure plate method. We conclude that the methods proposed in this study are effective for determining the hydraulic properties of weathered bedrock. The bedrock water retention curve exhibited small changes in volumetric water content throughout the measurement range where the pressure head, c, was greater than 2200 cm. The bedrock hydraulic conductivity function showed a small decrease in hydraulic conductivity in the very wet range of c greater than 230 cm, and then declined gradually with decreasing c.