Thermodynamics of hydrophobic polyacids.
The thermodynamics of deprotonating hydrolyzed 1-1 copolymers of maleic anhydride with pentyl, hexyl and octyl vinyl ether was investigated by calorimetric and potentiometric methods. These polyacids undergo a transition from a compact to a random coil conformation upon ionization in aqueous media. The results were compared with those obtained previously for similar copolymers with smaller alkyl side-chains. The contributions of the enthalpy and entropy to the free energy were analyzed. The major effects appeared to be related to the charging of the compact form of the polyacids, the electrostriction of water by the completely ionized dicarboxylate groups and the reorganization of water around newly exposed alkyl side-chains arising from the conformational transition.
Martin
P J
PJ
Department of Chemistry, Rutgers, State University of New Jersey, New Brunswick, New Jersey 08903 USA.
Strauss
U P
UP