Summary for Library of Congress control number 2007464845


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Summary: We examined adsorption of target molecules through a multiple-
contact interaction in a thermo-sensitive heteropolymer gel which can
undergo a volume transition at 34 C in water. Multi-valent anionic target
molecules were adsorbed electrostatically by monovalent cationic adsorbing
sites in the gel. The overall affinity (SK) between the gel and the target
molecule was calculated from the initial slope of the Langmuir adsorption
isotherm: [Tads] = KS[Tsol]/(l + K[Ts]), where S, K, [T,o] and [Tads]
represent the number of adsorption sites per unit volume of the gel, the
effective binding constant, the equilibrium  target concentration in the
external solution, and the target concentration adsorbed in the gel,
respectively. The affinity for the collapsed gel at 60 oC was studied in terms
of the concentrations of three factors: the adsorber ([Ad]), the coexistent salt
(replacement ion, [Re]), and the cross-linker ([XI]). We found that the
relationship between the affinity and these factors can be summarized by the
following formula first suggested by T. Tanaka:
Affinity, SK cC[Ad]ex
[Re]                [Ad    j
Here c is a constant and p is the number of the contact points between the
adsorber units and the target molecule.
tThis work was largely carried out in the Department of Physics and Center for Materials Science and
Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139.



Library of Congress subject headings for this publication:
Polymers -- Congresses,
Polymerization -- Congresses,