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