Surface forces arising from adsorbed ionic copolymers with hydrophobic and hydrophilic segments in colloidal dispersions

Leong, Y.K., Ong, B.C., Tan, J.H., Chandramalar, A.V.M., and Lim, Y.Y. (2003) Surface forces arising from adsorbed ionic copolymers with hydrophobic and hydrophilic segments in colloidal dispersions. Journal of Rheology, 47 (1). pp. 59-69.

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Abstract

The effects of ionic copolymers with hydrophobic segments on the yield stress–pH behavior of ZrO2 dispersions were evaluated. These polyelectrolytes were two alternating copolymers; diisobutylene-maleic acid and alpha-methyl styrene-maleic acid, and a random styrene-maleic acid copolymer. At low concentrations, all three copolymers caused a much greater reduction in the maximum yield stress, tau ymax (at the neutral charge condition), compared with hydrophilic polyacrylic acid and acrylic acid-ester polymers. The reduction in tau ymax was as much as 75%. The much larger reduction in tau ymax was attributed to a thicker steric layer formed by the ionic copolymers with hydrophobic segments. At higher concentrations, all three copolymers caused tau ymax to increase. This was attributed to significant hydrophobic effects and attraction. The degree of hydrophobic segment aggregation at the closest point of interaction between particles is now higher. This also caused an overall increase in the entropy relative to the state when the particles are far apart, as the degree of hydrogen bonding among water molecules is less when the hydrophobic segments are aggregated.

Item ID: 6669
Item Type: Article (Refereed Research - C1)
Keywords: alternating copolymers; hydrophobic effects and interaction; polyelectrolytes; yield stress; zeta potential; zirconia
ISSN: 1520-8516
Date Deposited: 09 Feb 2010 01:55
FoR Codes: 03 CHEMICAL SCIENCES > 0306 Physical Chemistry (incl Structural) > 030603 Colloid and Surface Chemistry @ 100%
SEO Codes: 86 MANUFACTURING > 8610 Ceramics, Glass and Industrial Mineral Products > 861099 Ceramics, Glass and Industrial Mineral Products not elsewhere classified @ 70%
86 MANUFACTURING > 8615 Instrumentation > 861503 Scientific Instruments @ 30%
Citation Count from Web of Science Web of Science 2
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