the invention relates to novel demulsifiers for use in the demulsification of oils from water and vice versa , including the demulsification of crude oil from sea water or brine . in particular , the present invention relates to novel demulsifiers which are environmentally friendly , or ‘ green ’, and which can be used without restriction on - site in offshore oil drilling fields , for example in the north sea . the novel demulsifiers are based on the reaction product of alkoxylated polyols or polyol esters with dicarboxylic acids .