Water sorption in poly(zwitterions) of the ammonioalkoxydicyanoethenolate type

Abstract

Water sorption by amorphous (meth)acrylic poly(zwitterions)‐bearing quaternary ammonioalkoxydicyanoethenolate side groups , dipole moment μ(D) = 25.9 and 30.8 for p = 2 and 3, respectively was studied at 23°C over a broad range of water activity a (0.14–0.98). Water diffusion is nearly Fickian (Ds = 5.9 10−7 cm2.s−1 for a = 0.63) and the sorption isotherms may be quantitatively analyzed according to the Guggenheim‐Anderson‐De Boer equation for a multilayer process characterized by a number of site‐bound water molecules per monomeric unit, nm ⋑ 0.7. The Flory χ interaction parameter is a strongly increasing function of the water content in the glassy hydrated systems and it always remains higher than 0.75. Clustering of water molecules (Zimm‐Lundberg theory) is never observed. Differential scanning calorimetry allows to quantify nonfreezable bound water (type I) of strong plasticization efficiency, n(I) = 2.8 mol. of water per monomeric unit, and it points out the quasisimultaneous emergence of low amounts of freezable bound water (type II) crystallizing at −40°C and melting at −1°C and of bulkfree water (type III, n(II)/n(III) ⋑ 0.1). All these typical features distinguish these rather hydrophobic poly(zwitterions) from their hydrophilic homologues of the quaternary ammoniopropanesulfonate type . © 1995 John Wiley & Sons, Inc.

Swelling of Hydroxypropyl Methylcellulose Matrix Tablets. 2. Mechanistic Study of the Influence of Formulation Variables on Matrix Performance and Drug Release

“…The average value of 4 × 10 -7 cm 2 /s thus obtained is in general agreement with the water diffusivity observed in organic solids or polymer matrices. 19,[21][22][23] Finally, the time differences for complete water penetration (denoted by the sharp decrease of the apparent glassy core at later times) into the center of the tablets deserve comment. The differences in the time required for front convergence among the MW series do not follow the rank order with respect to HPMC viscosity grade or particle size.…”

Poly(ammonioalkanesulfonate) Blends with Polar Organic Species and Alkali Metal Salts: Structure, Glass Transition and Ionic Conductivity

“…A similar but more significant trend has been reported for some polysoaps such as A-11M-3 and 4 and M-11M-3 and 4 (⌬T g ϳ 9-15°C) where the quaternary ammonio nitrogen carries one bulky n-butyl radical [14]. However, for a different series of polyzwitterions of the ammonioalkoxydicyanoethenolate type (N + -(CH 2 ) p -O-CO-C Ϫ (CN) 2 ), a T g decrease actually occurs when increasing the length of the intercharge arm from p = 2 to p = 3 [36].…”

Water sorption and diffusion studies in an epoxy resin system

“…At more elevated temperatures, isotherms approach linearity, revealing simple solution sorption, which is asymptotically approximated by Henry's Law. 16 The negative and positive deviations of the experimental results from Henry's Law of isothermal equilibrium water absorption have been described by Galin and Galin,43,44 in other polymeric systems by use of the Guggenheim-Anderson-de Boer (GAB) isothermal absorption model. 45 Infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy also confirm the formation of hydrogen bonds between water and the polar groups of the resin.…”

“…The negative deviations of the experimental results from Henry's Law at the first stages of isothermal equilibrium water absorption (especially for specimens with small amount of plasticizer) are attributed to the Langmuirian mode of absorption due to the formation of hydrogen bonds. The amount of bonded water and the potential of the bonds between the different types of absorbed water layers are estimated by use of the GAB isothermal absorption model, 43,44 which can also describe the positive deviations from Henry's Law at the last stages of absorption due to formation of water clusters. 4 Thermomechanical analysis (TMA) experiments were also performed to detect the glass transition temperature (T g ) and the expansion coefficient (a g ) of the materials under investiga-tion, as relaxation phenomena and changes in the free volume influence the diffusion coefficient and the water content at saturation.…”