Interaction of some solutes with certain cationic polymers and its effect on film permeability

Abstract

SynopsisPermeabilities of cast films of certain cationic acrylate methacrylate copolymers have been determined using a double (donor and acceptor) compartment cell. Permeation rates of urea (nonionic permeant) and sodium chloride (ionic permeant) were determined as functions of the polymer cation content. A decrease in film permeability accompanied the decrease in polymer cation content generally; the change was more marked with sodium chloride compared with urea. The films were also generally more permeable to urea; the difference increased at lower polymer cation content t o about 400-fold. While urea promoted film swelling, sodium chloride decreased it. Electron micrographs of the film section displayed compact skin zones which must be swelled to allow solute permeation. Asymmetry characterized the flux, the film lower surface (in contact with the mold during casting) being more permeable than its upper surface. This effect was more pronounced when sodium chloride was used as permeant.

Solvent effect on viscosities of aqueous coacervated systems of acrylate methacrylate copolymer

“…This solvation of the polymer promotes the extent of polymer–solvent interaction, thus accounting for the increase in viscosity. For instance, organic solutions of the polymer are more viscous than the corresponding aqueous dispersion 4. Below this point (i.e., 20% v/v) the increasing amounts of the nonsolvent (i.e., water) probably caused flocculation of the polymer particles to a polymer network, hence the increase in viscosity as the ethanol content decreased from 20 to 10%.…”

“…These are water‐insoluble copolymers that have applications in the film coating of drug particles for controlled release 1, 2. Aqueous dispersions of these polymers can be formed by a coacervation technique whereby excess water (i.e., nonsolvent for the polymer) is added to an ethanol solution of the polymer to form a latex dispersion of submicroscopic particle size 2–4…”

Transport of sodium chloride, urea, and creatinine through membranes derived from methylmethacrylate‐co‐methacrylic acid and its ionomers

“…Interaction of charged groups on the membrane pore walls with ionic solutes to cause attraction and/or repulsion has been proposed as a solute mechanism for lower permeability of ionic solutes in polymer membranes. [20][21] Hydration of the cations may also be an important factor for the transport properties of the mem- In the immediate vicinity of the ion, there is a shell of water molecules that are more or less immobilized by the high field due to the cation. Surrounding this, there is a second region; the third region around the ion comprises all the water sufficiently far from the ion that its effect is not felt.…”

“…Interaction of charged groups on the membrane pore walls with ionic solutes to cause attraction and/or repulsion has been proposed as a solute mechanism for lower permeability of ionic solutes in polymer membranes. [20][21] Hydration of the cations may also be an important factor for the transport properties of the mem-…”