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Water-based latex dispersions: 4. Exchange dynamics and residence times of nonylphenol ethoxylate in concentrated latex dispersions

Catherine Boissier (Institutionen för kemi- och bioteknik) ; Jan-Erik Löfroth (Institutionen för kemi- och bioteknik) ; Magnus Nydén (Institutionen för kemi- och bioteknik) ; S. Schantz
Journal of Colloid and Interface Science (00219797). Vol. 292 (2005), 1, p. 63-70.
[Artikel, refereegranskad vetenskaplig]

The equilibrium residence times of the nonionic surfactant nonylphenol ethoxylate (NP100) in a latex dispersion were determined using NMR diffusometry. At 16% w/w particle concentration and 0.12, 0.43 and 0.81% w/w NP100, the residence times of the surfactant were 0.16, 1.02 and 4.73 s in solution (τA) and 0.3, 0.37 and 0.61 s on the surface of the particles (τB), respectively. At even higher particle concentration (>45% w/w), τA and τB were 1.47 and 2.2 s. Calculating the number of collisions that ought to result in adsorbed species, at 16% w/w, only 2, 5 and 2‰ (corresponding to 0.12, 0.43 and 0.81% w/w NP100) resulted in adsorption, whereas at >45% w/w, only 12‰ resulted in adsorption, which suggested that the surfactant was irreversibly adsorbed on the particles. The small increase in collision frequency with increased particle concentration could be a result of a diffusion controlled adsorption, while an energy barrier for desorption controlled the overall exchange dynamics in the dispersion. The slow dynamics in the dispersion was controlled, mainly by the nonylphenol group, which gave NP100 a strong preference to surfaces. In addition, the chain length of the poly(ethylene glycol) (PEG) group changed the solution behavior from being that of a typical surfactant to that of a polymer.

Denna post skapades 2010-01-26.
CPL Pubid: 110933


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Institutionen för kemi- och bioteknik (2005-2014)



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