{HEAD ~ Plastics} which cure in a series of steps having urethane, urea, siloxane and {TAIL ~ acrylate} groups 
having
{ HEAD ~ Plastics } which cure in a series of steps having urethane , urea , siloxane and { TAIL ~ acrylate } groups
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH