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