Guan Xueqian, Huang Zhiyu, Lu Hongsheng, Sun Dejun
College of Chemistry and Chemical Engineering , Southwest Petroleum University , Chengdu 610500 , P. R. China.
Key Laboratory of Colloid and Interface Chemistry, Ministry of Education , Shandong University , Jinan 250100 , P. R. China.
J Phys Chem B. 2019 Apr 11;123(14):3096-3102. doi: 10.1021/acs.jpcb.8b12060. Epub 2019 Mar 27.
Binary mixtures of water and organic solvents are described as the aqueous solutions of organic solvents, which are usually spatially heterogeneous on the scale of a few molecular sizes but homogeneous on longer length scales, that is, microheterogeneity. For the water-organic solvent binary mixtures with microheterogeneity, most organic solvents are miscible with water at any ratio. Interestingly, some slightly water-miscible organic solvents can also be used to prepare binary mixtures with microheterogeneity. In this study, N, N-dimethylcyclohexylamine (DMCHA) was used to prepare binary mixtures with microheterogeneity and CO switchability. With the help of conductivity, Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, and dynamic light scattering measurements, we found that water molecules are hydrogen-bonded together to form clusters over the water content range of 9 to 27 wt %, exhibiting microheterogeneity in the binary mixture. The size of the water clusters increases slightly with increasing water content. What is more, the DMCHA-water mixtures can be reversibly split into two phases by alternate bubbling of CO and N, exhibiting excellent CO switchability. The binary mixtures can be used as reaction media for the synthesis of CaCO nanoparticles. Binary mixtures with microheterogeneity can also be formed under high salinity or high temperature conditions or be prepared using other slightly water-miscible organic solvents, opening up more interesting possibilities for binary mixtures with microheterogeneity.
水与有机溶剂的二元混合物被描述为有机溶剂的水溶液，其在几个分子大小的尺度上通常是空间不均匀的，但在更长的长度尺度上是均匀的，即微观不均匀性。对于具有微观不均匀性的水 - 有机溶剂二元混合物，大多数有机溶剂可与水以任何比例互溶。有趣的是，一些微溶于水的有机溶剂也可用于制备具有微观不均匀性的二元混合物。在本研究中，N，N - 二甲基环己胺（DMCHA）被用于制备具有微观不均匀性和CO开关性的二元混合物。借助电导率、傅里叶变换红外光谱、紫外可见光谱和动态光散射测量，我们发现水分子通过氢键结合在一起形成簇，在水含量为9至27 wt％的范围内，二元混合物呈现出微观不均匀性。水簇的尺寸随水含量的增加而略有增加。此外，通过交替鼓入CO和N，DMCHA - 水混合物可可逆地分成两相，表现出优异的CO开关性。该二元混合物可作为合成碳酸钙纳米颗粒的反应介质。具有微观不均匀性的二元混合物也可在高盐度或高温条件下形成，或使用其他微溶于水的有机溶剂制备，为具有微观不均匀性的二元混合物开辟了更多有趣的可能性。
