The solubility properties of amorphous poly[2,2-dicyano-l-[2-(2-(methacryloyloxy)ethyldimethylammonio)- ethoxy]-ethenolate] (zwitterionic lateral group of/~ = 25.9 D) investigated in 43 solvents of widely differing polarity may be interpreted in terms of solvent molar refractivity (dispersion interactions), dipole moment (dipolar interactions), basicity (donor-acceptor interactions with the ammonium site) and hydrogen-bonddonating power (hydrogen bonding to the anionic site). In dimethylformamide, representative of strongly dipolar aprotic media, the phase diagram is characterized by a lower critical solution temperature corresponding to a lower 0 temperature of about 65.8 + 1 °C. Coil expansion at 25°C, as derived from intrinsic viscosity measurements, is an increasing function of the concentration of added lithium salts (~< 1.5 tool 1-1), and the order of anion efficiency is CI- > Br- > I- > C10?. In trifluoroethanol, representative of weakly associated and strongly protic solvents, the addition of tetramethylammonium salts (~< 1 mol 1-1) results in coil expansion only in the case of the more polarizable C10? and I- anions, while CI- and Br- promote chain collapse. The hydrophobic polyzwitterion becomes water soluble at 25°C only in the presence of high salt concentrations, such as NaSCN > 2.5 mol 1-1, ZnC12 > 5 mol 1-1, C2HsNH~-NO 3 > 6 tool 1-1, and the phase diagram is characterized by an upper critical solution temperature strongly dependent on salt concentration (dT/d[NaSCN] =-70°Clmol - 1). In strongly acidic media, such as concentrated H2SO 4, HC104 aqueous solution (40-60 wt%) or methanesulfonic acid, partial protonation of the anionic sites transforms the polyzwitterion into a water soluble cationic polyelectrolyte.
Посилання на статтю:
Poly(ammonio alkoxydicyanoethenolate)s as new hydrophobic and highly dipolar polyzwitterions: 3. Solubility properties / Marie-Laure PujoI-Fortin and Jean-Claude Galin // Polymer. – 1994. – Vol 35. – P. 1462-1472.