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

摘要

The micellization of F127 (E98P67E98) in dilute aqueous solutions of polyethylene glycol (PEG6000 andudPEG35000) and poly(vinylpyrrolidone) (PVP K30 and PVP K90) is studied. The average hydrodynamicudradius (rh,app) obtained from the dynamic light scattering technique increased with increase in PEG concentrationudbut decreased on addition of PVP, results which are consistent with interaction of the micellesudwith PEG and the formation of micelles clusters, but no such interaction occurs with PVP. Tube inversionudwas used to determine the onset of gelation. The critical concentration of F127 for gelation increased onudaddition of PEG and of PVP K30 but decreased on addition of PVP K90. Small-angle X-ray scatteringud(SAXS) was used to show that the 30 wt% F127 gel structure (fcc) was independent of polymer typeudand concentration, as was the d-spacing and so the micelle hard-sphere radius. The maximum elasticudmodulus (G0udmax) of 30 wt% F127 decreased from its value for water alone as PEG was added, but was littleudchanged by adding PVP. These results are consistent with the packed-micelles in the 30 wt% F127 geludbeing effectively isolated from the polymer solution on the microscale while, especially for the PEG, beingudmixed on the macroscale.