Turov Vladimir V, Gun'ko Vladimir M, Krupska Tetyana V, Borysenko Mykola V, Kartel Mykola T
Chuiko Institute of Surface Chemistry, 17 General Naumov Street, 03164 Kyiv, Ukraine.
Chuiko Institute of Surface Chemistry, 17 General Naumov Street, 03164 Kyiv, Ukraine.
J Colloid Interface Sci. 2021 Apr 15;588:70-83. doi: 10.1016/j.jcis.2020.12.065. Epub 2020 Dec 31.
Various nanosilica characteristics depend on hydrophobization strongly affecting interfacial phenomena. Is it possible to prepare hydrophilic samples with hydrophobic silica (AM1) alone and in blends with hydrophilic one (A-300)? It can be done with addition of a small amount of water to the powders which then are mechanically treated.
Nanosilicas were characterized using adsorption, desorption, microscopic, spectroscopic, and quantum chemistry methods. H NMR spectroscopy and cryoporometry were applied to AM1 and AM1/A-300 blends wetted and mechanically treated. Wetted blends were studied with additions of n-decane and chloroform-d.
The powders wetted at h = 0.3-3.0 g of water per gram of dry solids have increased bulk density. Samples are in gel-like state at h = 4-5 g/g. Water interaction energy with nanoparticles nonmonotonically depends on h (maximal at h = 3 g/g). Upon mechanical treatment of wetted blends (h < 1.5 g/g), separated AM1 structures are absent. At greater h values, blend reorganization occurs to form AM1 aggregates covered by A-300 shells. Organics can displace water from mesovoids toward narrower pores inaccessible for larger molecules or into larger voids to reduce the contact area between immiscible liquids. Freezing point depression caused by confined space and dissolution effects is affected by the blend organization.
各种纳米二氧化硅的特性强烈依赖于疏水化作用，这会影响界面现象。仅使用疏水二氧化硅（AM1）以及将其与亲水二氧化硅（A - 300）混合，是否有可能制备出亲水样品？向粉末中添加少量水然后进行机械处理即可实现。
使用吸附、解吸、显微镜、光谱和量子化学方法对纳米二氧化硅进行表征。对湿润并经过机械处理的AM1以及AM1/A - 300混合物应用了核磁共振氢谱和低温孔隙测定法。对添加了正癸烷和氘代氯仿的湿润混合物进行了研究。
每克干固体中加入0.3 - 3.0克水湿润后的粉末堆积密度增加。在每克加入4 - 5克水时，样品处于凝胶状状态。水与纳米颗粒的相互作用能非单调地依赖于水的添加量（在每克加入3克水时达到最大值）。对湿润混合物（水添加量小于1.5克/克）进行机械处理后，不存在分离的AM1结构。在水添加量更大时，混合物会重新组织形成被A - 300壳层覆盖的AM1聚集体。有机物可将水从中等孔隙排向大分子无法进入的更窄孔隙，或排入更大的孔隙以减少不混溶液体之间的接触面积。由受限空间和溶解效应导致的凝固点降低受混合物组织的影响。
