Impact of Water on the Miscibility of DAB-dendr-(NH₂)₆₄ and Benzene

Abstract

The miscibility of the fifth-generation 1,4-diaminobutane poly(propyleneimine) (DAB-PPI) dendrimer and benzene was investigated. The liquid-liquid phase transitions in mixtures containing from 0.02 to 0.26 weight fraction of the dendrimer were determined. It was shown that the miscibility of the dendrimer and benzene depend to a great extent on the water content in the system. The binary system dry dendrimer + dry benzene does not show a liquid-liquid phase split. The addition of small amounts of water (as small as 0.06 wt %) to the system induces complex phase behavior. The liquid-liquid phase transitions in the ternary systems DAB-PPI dendrimer + benzene + water (0.06 wt %) are accompanied by unusual changes in the properties of the coexisting phases. The influence of water on the 1 H NMR spectra of the fifth-generation DAB-PPI dendrimer dissolved in benzene was also investigated.

Phase Behavior of Poly(vinylpyrrolidone) Containing Amorphous Solid Dispersions in the Presence of Moisture

“…As the amount of water in this cosolvent system is increased, the miscibility of the hydrophobic amorphous drug with the more hydrophilic system is decreased, leading to amorphous−amorphous phase separation. This phenomenon has been documented for ternary solvent systems, and also reported for the felodipine−PVP−water system. , …”

“…As the amount of water in this cosolvent system is increased, the miscibility of the hydrophobic amorphous drug with the more hydrophilic system is decreased, leading to amorphous-amorphous phase separation. This phenomenon has been documented for ternary solvent systems, 37 and also reported for the felodipine-PVP-water system. 17, 27 Using methods described in the literature, the interaction parameters between water and the amorphous drugs used in this study can be calculated from moisture sorption isotherm data collected at 95% RH 8,38 and are listed in Table 4.…”

Effect of temperature and moisture on the miscibility of amorphous dispersions of felodipine and poly(vinyl pyrrolidone)

“…Essentially, when the interaction parameters between the solvent and each of the two miscible components are very different, the solvent induces immiscibilty. In another related example, a system consisting of a macromolecular dendrimer and benzene, it was observed that the miscibility of the system was very dependent on the water content, with small levels of moisture resulting in the formation of two liquid phases 41. There is also some evidence that moisture may promote phase separation in amorphous pharmaceutical systems 31, 42.…”

UV spectral features of poly(propylene imine) dendrimers

“…A linear dependence of scattering loss versus λ −4 was observed in a wide spectral range with the slope increasing for higher dendrimer concentrations, though some influence of background absorption was still evident. An increase of light scattering in dendrimer solutions of higher generations is well understood taking into account a corresponding increase of viscosity [15] and the phase behaviour in amine terminated dendrimer solutions [16].…”