Calorimetric and X-ray studies of clathrate hydrates of tetraisoamylammonium polyacrylates.
The structure of clathrate hydrates with tetraisoamylammonium polyacrylate salt incorporated as guest has been studied in this work. Also, quantitative studies on the stability changes of the clathrate hydrates with different degrees of cross-linking of the guest polymer (varied from 0 to 3%) have been conducted. A single crystal X-ray diffraction study of a crystal of the hydrate with linear (uncross-linked) tetraisoamylammonium polyacrylate as guest reveals a hexagonal structure (space group P6m2, a = 12.15 A, c =12.58 A at 100 K) with 39 host framework water molecules per one guest monomeric unit. Powder X-ray diffraction analyses confirm the identity of the above crystal structure of the hydrate with linear guest polymer and the crystal structure of the hydrates with cross-linked guest (hexagonal, a = 12.25 A, c =12.72 A at 276 K). In order to quantitatively determine the stability differences of the hydrates with the included guests having various degrees of cross-linking of the anionic chain, a series of differential scanning calorimetry measurements of the fusion enthalpy of the hydrate samples has been carried out. On the basis of the results obtained, a structural model describing the decrease in the stability of the clathrate hydrates with tetraisoamylammonium polyacrylate guest as a function of the degree of cross-linking of the guest polymer has been suggested.
Terekhova
Irina S
IS
Nikolaev Institute of Inorganic Chemistry, M.A. Lavrentyev Institute of Hydrodynamics, Siberian Division of RAS, Novosibirsk, Russia. clat@che.nsk.su
Manakov
Andrey Yu
AY
Soldatov
Dmitriy V
DV
Suwinska
Kinga
K
Skiba
Sergey S
SS
Stenin
Yuri G
YG
Villevald
Galina V
GV
Karpova
Tamara D
TD
Yunoshev
Alexander S
AS