PEG (polyethylene glycol) is used in hybridoma technology for:
Efficient cell fusion must overcome hydration repulsion keeping lipid bilayers approximately two nanometers apart due to ordered water molecules bound to phosphatidylcholine headgroups. Polyethylene glycol with molecular weight 1450 to 4000 daltons is extremely hygroscopic linear polymer containing repeating ether oxygens that strongly bind water through hydrogen bonding, lowering water activity dramatically and creating osmotic stress that forces membranes into close proximity below one nanometer. At concentrated 40 to 50 percent weight per volume, PEG disrupts lipid packing, induces inverted
Ref: Lentz J Mol Biol PEG fusion membrane dehydration; Alberts MBoC membrane fusion hemifusion stalk; Nature Protocols PEG hybridoma.