Conductivty Studies On Conductive Percolation Of Microemulsions And Critical Anomalies Of Two S_N1 Hydrolysis Reactions In Critical Binary Solutions

In this thesis,we studied the conductive percolation of AOT/H2O/isooctane microemulsions with and without the various kind of polymers and the reaction rate constant of SN1 hydrolysis reaction in binary liquid mixtures near thermodynamic critical-points by the measurement of conductometry,this two contents presented as following:(1)The temperature induced conductive percolation curves of the ?=22.2 AOT/H2O/isooctane microemulsions and with the addition of polymers(PEG,PEI,PVP and PBD)had been measured,and obtained the threshold temperature of percolation Tp by fitting with SBE equation.We found that addition of PEG and PBD is beneficial to the percolation while adding PEI is adverse to that,and the additive PVP do not have effect on the percolation process.The thermodynamic parameters of the percolations calculated by the phase separation model,and a thermodynamic model of percolation has been built by ourselves and we calculated the associated enthalpies of two close contacting droplets ?Hclc0 combine with the interaction enthalpies-?H? of two droplet determined by ITC.The experimental results can be interpreted by the mobility of the droplet interfaces varied with the additives.(2)Rates of SNl hydrolysis reactions for 2-chloro-2-methyIbutane in the critical solution of(isobutyric acid + water)and for 2-bromo-2-methylpropane in the critical solution of(triethylamine + water)in the one-phase region and at various temperatures have been determined respectively by conductance measurements.It was found that the reaction rates at different temperatures for those two Snl reactions were well described by the Arrhenius equation in the noncritical region,while near the critical points the critical slowing down was clearly detected.These results are inconsistent with what reported in the literature(J.Phys.Chem.A 2003,107,8435-8443).Reanalyzing the literature data,we found that as a proper Arrhenius equation served as the background,the critical slowing down rather than speeding up was detected whither the reactions carried in one-phase region or two-phase region.The experimental data from different sources were fitted with a simplified cross over formulism characterizing the critical effect of the reactions to determine the critical slowing down exponents,which were found to be about 0.04,showing that only a dynamic critical slowing down could be detected for these reaction systems.It was attributed to the fact that the SNl hydrolysis reaction is neither the first nor the pseudo first reaction in the revised direction and the kinetic measurements were carried in a region quite far from the equilibrium of the reactions.