溶液中纳米尺度疏水相互作用的X射线散射研究

项目名称： 溶液中纳米尺度疏水相互作用的X射线散射研究

项目编号： No.11204285

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 物理学I

项目作者： 黄宁东

作者单位： 中国科学技术大学

项目金额： 30万元

中文摘要： 疏水相互作用是理解分子及纳米量级微观结构和自组织过程的关键之一。近年来理论及模拟研究表明疏水相互作用在纳米尺度表现出对疏水介质尺寸的依赖，但缺乏直接的实验支持。与其它技术相比X射线中角散射能有效探测到纳米量级的关联与相互作用。本项目拟采用这一手段研究直径约为1纳米的(CnH2n+1)4N+(n=1-5)四烷基季铵(R4N+)阳离子在溶液中的疏水相互作用。通过测量水溶液中阳离子和温度对X射线中角散射的影响，结合超网链方法定量分析来系统研究R4N+阳离子之间疏水相互作用的性质及其与离子尺寸的关系。通过比较水溶液与有机溶剂中R4N+离子之间的关联来探讨疏水相互作用对离子间相互吸引的贡献。进一步探讨溶液中碱卤化合物的存在对离子间疏水相互作用的影响，达到模拟现实或人为控制疏水相互作用的目的。本研究有望深入透彻理解溶液中纳米尺度疏水相互作用行为，并有助于对诸如有机分子聚集过程和蛋白质折叠等现象的理解。

中文关键词： 水溶液；疏水相互作用；离子关联；X射线中角散射；两亲离子

英文摘要： Hydrophobic interactions between apolar solutes or apolar part of solutes are essential to understanding micro-structure and self assembling processe at molecular and nanometer scale. Recent advances in theory and simulation predicted a size dependence of hydrophobic effects and a crossover length from microscopic to macroscopic behavior around subnanometer，however few advances have been achieved from experimental aspects since then. Here we propose a systematic study on this issue by X-ray scattering at middle angle range in aqueous solutions of tetraalkyl-ammonium (CnH2n+1)4N+(n=1-5)cations with diameters around nanometer. X-ray scattering at middle angle about Q=1.0?-1 was found be to senstitive to cation association around nanometer scale and contains more contribution from (CnH2n+1)4N+ cations than that from water solvents; hence is capable of measuring hydrophobic interaction between (CnH2n+1)4N+ cations. Through evaluating the effects of R4N+ cations and temperature on scattering intensity in combination with calculation of scattering intensity using hypernetted chain method and effective potential between solvated ions, quantitative understanding of hydrophbic effects at nanometer scale as well as its size dependence can be achieved. Furthermore, the influence of additional alkali halide to solutions o

英文关键词： aqueous solution；hydrophobic interaction；ion association；middle angle X-ray scattering；amphiphilic ion