It may be like these Sigma-Aldrich products..
#438197 for a random PEG-PPG copolymer, but smallest has Mn ~ 2,500
#435406 block PEG-PPG copolymer, smallest has Mn~ 1,100; this is a viscous liquid
I cannot find exactly what you describe; suggest you call SA tech support 1-800-325-5832.
Good Luck !