Method of demulsifying crude oil and water mixtures with copolymers of acrylates or methacrylates and hydrophilic commonomers

A method of demulsifying a crude oil and water mixture, which method comprises adding to the mixture an oil and water demulsifying effective amount of a copolymer which is the copolymerization reaction product of:

• A) an acrylate or methacrylate of an oxyalkylate of the formula
• R.sup.1 --O--[--AO--].sub.x --H
• where R.sup.1 is a radical of a monohydric or polyhydric alcohol or alkylphenol or a radical of an alkylphenol/formaldehyde or alkylphenol/acetaldehyde condensate, AO is an ethylene oxide, propylene oxide or 1,3-butylene oxide radical or a mixture of these radicals or blocks of these radicals and x is from 5 to 120,
• B) a hydrophilic comonomer of the formula ##STR4## wherein R.sup.2 is hydrogen, ##STR5## R.sup.3 is hydrogen or --COOH and R.sup.4 is hydrogen or --CH.sub.3,
• such that one or more of the radicals is a hydrophilic group, and the weight ratio of A) to B) being from 300:1 to 1:50, and further wherein said reaction product has all or at least some of its free hydroxyl groups blocked.