{TAIL ~ a polymer outer layer} coupled to the first metallic material opposite {HEAD ~ the substrate}, and 
{ TAIL ~ a polymer outer layer } coupled to the first metallic material opposite { HEAD ~ the substrate } , and
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH