# Shape of PEG in water

According to the chemical formula $$\ce{H−(O−CH2−CH2)_n−OH}$$ of polyethylene glycol, or PEG, I assume that this organic compound has a long chain structure when it is dry and in powder form. (This is also what guys in the chemistry field say.)

But when PEG is dissolved in water, would it form some structure like a cluster or would it remain a long chain? Can we somehow calculate the diameter of a dissolved PEG molecule when $$n$$ is given? Or the dissolved PEG molecules band randomly so there are no calculations for an average diameter statistically at all?

• Polymer molecules form individual "random coils" in solution. The end-to-end distance of the molecule and thereby also its coiled "diameter" (radius of gyration) scales linearly with molecular weight. The absolute numbers depend of course on the stiffness of the molecule, kind of solvent, solute-solvent interaction, and temperature. – Karl Jul 6 at 19:30