Sentence:  Related to micelle formation is the technologically important ability of detergent actives to congregate at <WSD>oil</WSD> water interfaces in such a manner that the polar ( or ionized ) end of the molecule is directed towards the aqueous phase and the hydrocarbon chain towards the oily phase . 
Meaning of the word marked with <WSD> tags:  an interface forming the boundary between the non-miscible liquids oil and water