Effect of salts on the electrical conductance of a fluorine-containing poly(carboxylic acid), PPFNA.
Electrical conductance and other solution properties of aqueous solutions of a fluorine-containing poly(carboxylic acid), (poly(9H,9H-perfluoro-2,5-dimethyl-3,6-dioxa-8-nonenoic acid), PPFNA) were studied with special attention to the salt effect. This polymer dissociated strongly resulting in a low pH value in unneutralized state (beta=0, beta: degree of neutralization). The specific conductance was the highest at beta=0 and decreased as beta increased. A considerable increase in conductance was observed by titrating NaCl at low beta, because large amounts of bound protons were released by addition of NaCl. The amounts of released protons exceeded those originally dissociated at beta=0. Such an anomalous proton liberation suggests that this polymer is a fairly strong polyacid but not a typical one such as poly(styrene sulfonic acid). Under fully neutralized state (beta=1), however, the solution conductance was lower than the sum of the polymer and NaCl added, due to polyion-salt ion interaction.
Minakata
Akira
A
Department of Physics, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu 431-3192, Japan. aminak@nifty.com
Nishio
Takuhiro
T
Kimura
Motoko
M
Yano
Shin-Ichi
S
Tanaka
Yoshito
Y
Shimizu
Tetsuo
T
D002264:Carboxylic Acids / Q000737:chemistry*; D004553:Electric Conductivity; D005461:Fluorine / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry; D012492:Salts / Q000737:chemistry*; D013696:Temperature; D014783:Viscosity; D014867:Water / Q000737:chemistry
D002264:Carboxylic Acids; D011108:Polymers; D012492:Salts; D014867:Water; D005461:Fluorine