A versatile method for adjusting thermoresponsivity:: Synthesis and 'Click' reaction of an azido end-functionalized poly(N-isopropylacrylamide)

The 2-chloropropionamide derivative featuring an azido group is used as the initiator for the ATRP of N-isopropylacrylamide (NIPAM) with copper(I) chloride (CuCl) and tris[2-(dimethylamino)ethyl]amine (Me6TREN) to produce the PNIPAM end-functionalized with an azido group. Subsequently, the 'click' reaction between the azido end-group and acetylene derivatives is demonstrated to produce PNIPAM in which the end-groups are modified by the phenyl, 4-phenoxyphenyl, butyl, octyl, carboxylic acid, and hydroxymethyl groups. The resulting PNIPAM derivatives show a LCST that ranges from 34.8 to 44.6 degrees C depending on the introduced end-group.