ISSN:
1435-1536
Keywords:
Associative polymers
;
NMR
;
self-diffusion
;
self-assembly
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The concentration and molecular weight dependence of the self-diffusion coefficient (D self) of associative polymers of HEUR-type in aqueous solution have been investigated using FT-PGSE-NMR technique. The idea of three-dimensional network formation as a result of aggregation of the hydrophobic end-groups of the polymer in junctions is supported through the observed dramatic lowering ofD self with increased concentration. The network-formation efficiency depends on the polymer molecular weight as well as the hydrophobicity of the end-groups. A double logarithmic dependence of the self-diffusion coefficient versus concentration (c) has been observed:D self∝c −a1,a2 . The first exponent,a 1, is valid at low concentration, 〈1% polymer per weight solution, and ranges from 0.5 to 1, whereas the second exponent,a 2, describing systems of higher concentration, ranges from 2 to 2.7.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00665990
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