Structural and physicochemical studies of hydration of crosslinked TBA polyacrylates with different substitution degrees of H+ ions with TBA+ ions

Abstract

ABSTRACTX‐ray powder diffraction studies and physicochemical studies have been carried out of the hydrate phases formed in binary water systems with crosslinked tetrabutylammonium (TBA) polyacrylates (n = 1%) in mixed [x(C4H9)4N + (100−x)H] form with low degrees of substitution of proton ions of the carboxylic groups in poly(acrylic acid) for TBA cations x = 40%, 30%, and 20%. As was shown by structural studies, the clathrate hydrate is formed in the water system with the polyacrylate in the mixed form with x = 40%. The structure is analogous to that of earlier studied hydrates formed by crosslinked polyacrylates in mixed [x(C4H9)4N + (100−x)H] form with higher values of x = ∼100%, 80%, and 60% and can be related to the tetragonal structure I, characteristic of the ionic clathrate hydrates of TBA salts with monomeric anions. Decomposition temperature and fusion enthalpy of the studied hydrate were determined using differential thermal analysis and calorimetric methods. It was revealed that the further decrease of x led to the destruction of clathrate hydrate framework. According to the results of X‐ray powder diffraction research, the phase of ice is crystallized instead of the hydrate phase in water systems with the polyacrylates with x = 30% and 20%. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46209.