ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
A descriptive model was developed, using viscometry and light scattering, that explains the anomalous rheological behavior of solutions of amphiphilic acrylic copolymers upon the addition of water. The rheological behavior can be explained by considering the relative magnitudes of three interactions: the intra-and intermolecular electrostatic interactions between the ionizable acid groups in the copolymer, the intramolecular hydrophobic in-teractions, and the intermolecular hydrophobic interactions. The initial addition of water enhances the ionization of the acid groups, causing the electrostatic interactions between the acid groups to dominate the other two interactions. This leads to expansion of the polymer molecules and, consequently, to a relatively constant viscosity during dilution with water. Upon attaining the maximum ionization of the acid groups on the chain, the intra-molecular hydrophobic interactions dominate the electrostatic repulsion, and the chains start to contract. Further addition of water leads to aggregation of the polymer chains into large polymolecular domains, resulting in a sharp decrease in the viscosity. Intermolecular hydrophobic interactions dominate the rheological behavior in this stage of water dilution. © 1996 John Wiley & Sons, Inc.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
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