Dissolution behaviour of model alkali-soluble emulsion polymers: effects of molecular weights and ionic strength |
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Authors: | M Siddiq K C Tam R D Jenkins |
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Institution: | (1) School of Mechanical and Production Engineering Nanyang Technological University Nanyang Avenue, Singapore 639798 Singapore, SG;(2) Union Carbide Asia Pacific Inc. Technical Center, 16 Science Park Drive The Pasteur, Singapore 118227, Singapore, SG |
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Abstract: | The dissolution behaviour of model alkali-soluble polymer emulsions with different molecular weights was studied using conductometric
and potentiometric titration and laser light scattering techniques. The behaviour of the copolymer was studied as a function
of the degree of neutralisation, α = NaOH]/COOH]. The polymer latex swells with increasing α values up to α = 0.5–0.7, after
which the dissociation of polymer chains commences. At α = 1.0, all the polymer latexes dissociate into individual polymer
chains. By combining the results of static and dynamic laser light scattering, we observed that the polymers have a compact
conformation at α = 0. This compact conformation changes to a random coil at around α = 0.5, which then becomes a fully extended
coiled conformation at α = 1.0, when all the COOH polymer groups are hydrolysed. The dissolution of low-molecular-weight polymers
is faster than that of high-molecular-weight polymers.
Received: 15 February 1999 Accepted in revised form: 13 July 1999 |
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Keywords: | Dissolution Molecular weights Ionic strength Neutralisation Light scattering |
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