{HEAD ~ The alkyl alcohol} is removed and the excess ethanolamine is reacted with ethylene or propylene carbonate to form {TAIL ~ the urethane diol} 
{ HEAD ~ The alkyl alcohol } is removed and the excess ethanolamine is reacted with ethylene or propylene carbonate to form { TAIL ~ the urethane diol }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL