{HEAD ~ sulfonated poly} coated on {TAIL ~ the polymer substrate membrane} to form an ion selective membrane, 
coated on
{ HEAD ~ sulfonated poly } coated on { TAIL ~ the polymer substrate membrane } to form an ion selective membrane ,
HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH