{HEAD ~ The diacetylenes} are useful as {TAIL ~ monomers} for preparing fluorinated polyether elastomers 
{ HEAD ~ The diacetylenes } are useful as { TAIL ~ monomers } for preparing fluorinated polyether elastomers
HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH