Soluble complexes in aqueous mixtures of low charge density comb polyelectrolyte and oppositely charged surfactant probed by scattering and NMR
2007 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 312, no 1, 21-33 p.Article in journal (Refereed) Published
A low charge density polyelectrolyte with a high graft density of 45 units long poly(ethylene oxide) side-chains has been synthesized. In this comb polymer, denoted PEO(45)MEMA:METAC-2, 2 mol% of the repeating methacrylate units in the polymer backbone carry a permanent positive charge and the remaining 98 mol% a 45 unit long PEO side-chain. Here we describe the solution conformation of this polymer and its association with an anionic surfactant, sodium dodecylsulfate, SDS. It will be shown that the polymer can be viewed as a stiff rod with a cross-section radius of gyration of 29 A. The cross section of the rod contracts with increasing temperature due to decreased solvency of the PEO side-chains. The anionic surfactant associates to a significant degree with PE045MEMA:METAC-2 to form soluble complexes at all stoichiometries. A cooperative association is observed as the free SDS concentration approaches 7 mM. At saturation the number of SDS molecules associated with the polymer amounts to 10 for each PEO side-chain. Two distinct populations of associated surfactants are observed, one is suggested to be molecularly distributed over the comb polymer and the other constitutes small micellar-like structures at the periphery of the aggregate. These conclusions are reached based on results from small-angle neutron scattering, static light scattering, NMR, and surface tension measurements.
Place, publisher, year, edition, pages
2007. Vol. 312, no 1, 21-33 p.
comb polymer; comb polyelectrolyte; polymer-surfactant association; polyelectrolyte-surfactant aggregate; small-angle neutron scattering; light scattering; NMR; surface tension; polyelectrolyte; surfactant; SDS
IdentifiersURN: urn:nbn:se:kth:diva-6677DOI: 10.1016/j.jcis.2006.09.004ISI: 000247286100004ScopusID: 2-s2.0-34249817580OAI: oai:DiVA.org:kth-6677DiVA: diva2:11453
QC 20100813. Uppdaterad från submitted till published (20100813).2005-09-222005-09-222010-09-01Bibliographically approved