{HEAD ~ The carbodiimide} can promote {TAIL ~ the formation} of crosslinks between carboxylate and amine groups of the polyelectrolytes 
promote
{ HEAD ~ The carbodiimide } can promote { TAIL ~ the formation } of crosslinks between carboxylate and amine groups of the polyelectrolytes
HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH