Sentence:  Related to micelle formation is the technologically important ability of detergent actives to congregate at oil water interfaces in such a manner that the polar ( or ionized ) end of the molecule is directed towards the aqueous phase and the hydrocarbon <WSD>chain</WSD> towards the oily phase . 
Meaning of the word marked with <WSD> tags:  (chemistry) a series of linked atoms (generally in an organic molecule)