Effect of water-soluble polymers, polyethylene glycol and poly(vinylpyrrolidone), on the gelation of aqueous micellar solutions of Pluronic copolymer F127

• Published in: Journal of colloid and interface science 2012-02, Vol.368 (1), p.336-341
• Main Authors: Ricardo, Nágila M.P.S., Ricardo, Nadja M.P.S., Costa, Flávia de M.L.L., Bezerra, Francisco W.A., Chaibundit, Chiraphon, Hermida-Merino, Daniel, Greenland, Barnaby W., Burattini, Stefano, Hamley, Ian W., Keith Nixon, S., Yeates, Stephen G.
• Format: Article
• Language: English
• Subjects: aqueous solutions; Chemistry; Clusters; Colloidal state and disperse state; composite polymers; Elastic modulus; Exact sciences and technology; F127; Gel; Gelation; gels; General and physical chemistry; Hydrodynamics; Inversions; Light scattering; Micelle; Micelles; Micelles. Thin films; Modulus; modulus of elasticity; Polyethylene glycol; Water soluble polymer; X-radiation
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2011.10.062

[Display omitted] ► Gelation of aqueous micellar solutions of Pluronic copolymer F127. ► Addition of polyethylene glycol (PEG) increases the critical gel concentration (cgc). ► Addition of poly(vinylpyrrolidone) (PVP) may decrease the cgc. ► The elastic modulus of the gel is much reduced on adding PEG, less so on adding PVP. ► 30wt% F127 gel has the face-centered cubic structure for both polymers. The micellization of F127 (E98P67E98) in dilute aqueous solutions of polyethylene glycol (PEG6000 and PEG35000) and poly(vinylpyrrolidone) (PVP K30 and PVP K90) is studied. The average hydrodynamic radius (rh,app) obtained from the dynamic light scattering technique increased with increase in PEG concentration but decreased on addition of PVP, results which are consistent with interaction of the micelles with PEG and the formation of micelles clusters, but no such interaction occurs with PVP. Tube inversion was used to determine the onset of gelation. The critical concentration of F127 for gelation increased on addition of PEG and of PVP K30 but decreased on addition of PVP K90. Small-angle X-ray scattering (SAXS) was used to show that the 30wt% F127 gel structure (fcc) was independent of polymer type and concentration, as was the d-spacing and so the micelle hard-sphere radius. The maximum elastic modulus (Gmax′) of 30wt% F127 decreased from its value for water alone as PEG was added, but was little changed by adding PVP. These results are consistent with the packed-micelles in the 30wt% F127 gel being effectively isolated from the polymer solution on the microscale while, especially for the PEG, being mixed on the macroscale.