Gelation of Pluronic F127-polyethylene glycol mixtures: relationship to PEG molecular weight.

The formation and melting of Pluronic F127 gels in the presence of polyethylene glycols (PEGs) has been studied. All the PEGs studied raised T1 and lowered T2 of 20% F127 gels; this effect was proportional to PEG concentration. At a certain critical "no-gel" concentration of PEG (Cng), F127 lost its ability to form gels. Cng was found to be inversely proportional to PEG molecular weight. An empirical relationship between Cng and PEG molecular weight was obtained which can be used to predict effects of PEGs of any molecular weight on F127 gelation.