i) a linear polymer selected from {HEAD ~ the group} consisting of linear hydrophobic biodegradable polymers and linear {TAIL ~ non degradable hydrophilic polymers} 
i ) a linear polymer selected from { HEAD ~ the group } consisting of linear hydrophobic biodegradable polymers and linear { TAIL ~ non degradable hydrophilic polymers }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL