Preferably {HEAD ~ the alkylene group} has one to ten carbon atoms, preferably one to six carbon atoms, and preferably is {TAIL ~ a methylene group}, —CH2— 
preferably is
Preferably { HEAD ~ the alkylene group } has one to ten carbon atoms , preferably one to six carbon atoms , and preferably is { TAIL ~ a methylene group } , — CH2 —
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH