In {TAIL ~ the compounds} of formula B1 and B2, {HEAD ~ R1} is in particular a poly propylene oxide chain or a poly tetramethylene oxide chain, but it can also represent a chain derived from dicarboxylic acids, diols, diamines or diisocyanates etc., by well known methods of poly condensation 
In { TAIL ~ the compounds } of formula B1 and B2 , { HEAD ~ R1 } is in particular a poly propylene oxide chain or a poly tetramethylene oxide chain , but it can also represent a chain derived from dicarboxylic acids , diols , diamines or diisocyanates etc . , by well known methods of poly condensation
REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH