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Further studies on the rheological properties of hydrophobically modified polyelectrolyte systems: effect of varying degree of ethoxylation
Author(s) -
Tam KC,
Ng WK,
Jenkins RD
Publication year - 2007
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.2172
Subject(s) - polymer , polyelectrolyte , polymer chemistry , associative substitution , ethylene oxide , macromonomer , aqueous solution , rheology , intramolecular force , chemistry , amphiphile , materials science , chemical engineering , organic chemistry , copolymer , composite material , engineering , catalysis
The rheological properties of aqueous solutions of a series of hydrophobically modified alkali‐soluble emulsion (HASE) polymers containing hydrophobic macromonomer with varying number of ethylene oxide (EO) units were examined. The viscosity of a 3 wt% HASE solution increased from 0.06 to 300 Pa s when the number of EO units changed from 0 to 30, and then decreased to 4 Pa s for 40 EO units. The formation of a network structure in the HASE polymer systems is caused by association of hydrophobic moieties in the solution rather than by physical chain entanglements. Two different associating mechanisms, namely the backbone and the multiple center associative mechanisms, are proposed for the HASE polymer with varying number of EO units. The backbone associative mechanism is applicable to HASE polymers with short EO spacer where the hydrophobic association is hindered by electrostatic repulsion on the backbone. In contrast, with longer EO spacer, hydrophobes from different polymer chains are able to associate, leading to the formation of multiple center associative junctions. The drastic reduction in the viscosity for 40 EO units in both dilute and semi‐dilute concentrations is attributed to the formation of a higher proportion of intramolecular associative junctions. Copyright © 2006 Society of Chemical Industry