A study of the microstructural and diffusion properties of poly(vinyl alcohol) cryogels containing surfactant supramolecular aggregates

TitleA study of the microstructural and diffusion properties of poly(vinyl alcohol) cryogels containing surfactant supramolecular aggregates
Publication TypeArticolo su Rivista peer-reviewed
Year of Publication2006
AuthorsTedeschi, A., Auriemma F., Ricciardi Rosa, Mangiapia G., Trifuoggi M., Franco L., De Rosa C., Heenan R.K., Paduano L., and D'Errico G.
JournalJournal of Physical Chemistry B
Volume110
Pagination23031-23040
ISSN15206106
KeywordsCryogels, Cryogenics, Diffusion in liquids, Drying, Hydrogel patches, Hydrogels, Ion chromatography, Microstructure, Polyvinyl alcohols, Supramolecular aggregates, Supramolecular chemistry, Surface active agents
Abstract

Surfactant-containing poly(vinyl alcohol) (PVA) cryogels have been prepared by drying and reswelling hydrogel patches, previously obtained by the freeze/thaw procedure, in decyltrimethylammonium bromide (C10TAB) aqueous solutions. The microstructural and diffusive properties of the resulting material have been characterized by a combined experimental strategy. Gravimetric measurements show that the cryogel maximum swelling is not affected by the surfactant. The surfactant concentration within the cryogel, measured by ion chromatography, is the same as that in the rehydrating surfactant solution. Electron paramagnetic resonance (EPR) spin-probe and small-angle neutron scattering (SANS) measurements show that surfactant self-aggregation in the gel is similar to that in water, occurring at the same critical concentration and resulting in the formation of micellar aggregates whose structure is not affected by the cryogel polymeric scaffold. However, both the micelle intradiffusion coefficients, measured by PGSE-NMR, and the spin-probe correlation times, measured by EPR, indicate that dynamic processes in the hydrogel are much slower than in bulk water. A quantitative analysis of these results suggests that the cryogel polymer-poor domains, in which surfactant molecules are solubilized, have an average dimension of ∼0.1 μm. Interestingly the experimental data also show that the polymer-poor phase contains more polymer than expected, suggesting that the spinodal decomposition, which occurs during the freezing step of cryogel preparation, is not complete or prevented by ice formation. © 2006 American Chemical Society.

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URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-33846065931&doi=10.1021%2fjp061941m&partnerID=40&md5=3b70f8ec3448d558bd4a21e910f136e6
DOI10.1021/jp061941m