Physicochemical and Structural Studies of Clathrate Hydrates of Tetrabutylammonium Polyacrylates

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• 作者：Irina S. Terekhova ; Andrey Yu. Manakov ; Vladislav Yu. Komarov ; Galina V. Villevald ; Alexander A. Burdin ; Tamara D. Karpova ; Eugeny Ya. Aladko
• 刊名：The Journal of Physical Chemistry B
• 出版年：2013
• 出版时间：March 7, 2013
• 年：2013
• 卷：117
• 期：9
• 页码：2796-2806
• 全文大小：447K
• 年卷期：v.117,no.9(March 7, 2013)
• ISSN：1520-5207

文摘

In this work, physicochemical and structural studies have been carried out for semiclathrate hydrates of linear (un-cross-linked) and cross-linked tetrabutylammonium polyacrylates with different degrees of cross-linking of the polymeric guest molecules (n = 0.5, 1, 2, 3%) and different degrees of substitution of proton ions of carboxylic groups in poly(acrylic acid) for TBA cations (x = 1, 0.8, 0.6). The changes in the hydrates鈥?stability and composition depending on the outlined parameters were examined in the course of phase diagram studies of the binary systems water鈥搕etrabutylammonium polyacrylates using differential thermal analysis method and calorimetric measurements of fusion enthalpies of the hydrates. Phase diagram studies of the binary system water鈥搇inear tetrabutylammonium polyacrylate revealed the formation of four hydrates. Based on the data of chemical analysis of hydrate crystals the compositions of all hydrates have been determined. Single-crystal X-ray diffraction studies revealed a tetragonal structure, space group 4/m, and unit cell parameters are close for different hydrates and lie in the ranges a = 23.4289鈥?3.4713 脜 and c = 12.3280鈥?2.3651 脜 (150 K). The structure can be related to tetragonal structure I typical for the clathrate hydrates of tetraalkylammonium salts with monomeric anions. Powder X-ray diffraction analyses confirmed the identity of the above crystal structure to that of the hydrates with cross-linked tetrabutylammonium polyacrylates. The behavior of TBA polyacrylate hydrates under the pressure of methane was studied and quantitative assessment of the gas content in the hydrates was made using volumetric analysis method.