Structural investigation of hydrate compounds of the tetraisoamylammonium form of polyacrylate ion exchange resins. Crystal structure of a clathrate hydrate of linear tetraisoamylammonium polyacrylate

Abstract

A polyhydrate of the tetraisoamylammonium salt of linear (uncrosslinked) polyacrylate (∼25 monomeric units in the polyacrylate chain) is described and compared to polyhydrates of cross-linked tetraisoamylammonium polyacrylates (0.5–3% of cross-linking with divinylbenzene or divinylsulfide). Powder X-ray diffraction reveals that the polyhydrate containing a linear polyacrylate molecule has the same structure (hexagonal, a = 12.26 A, c = 12.71 A at 3°C) as polyhydrates of the cross-linked polyacrylate molecules. A single crystal of the polyhydrate obtained from an aqueous solution of linear tetraisoamylammonium polyacrylate is studied by X-ray diffraction at −173°C. The structure is hexagonal; space group P-6m2; the polyhydrate framework is a slightly distorted variant of the hexagonal structure-I of clathrate hydrates.