In the compounds of formula B1 and B2, 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 {HEAD ~ well known methods} of {TAIL ~ poly condensation} 
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In the compounds of formula B1 and B2 , 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 { HEAD ~ well known methods } of { TAIL ~ poly condensation }
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 OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL