Aggregation Behavior of Poly(N-isopropylacrylamide) Semitelechelics with a Perfluoroalkyl Segment in Water

Two hydrophobically modified PNIPAM semitelechelics PxF9 were prepared by clicking PNIPAM containing an azide endgroup (PxN3) with nonadecafluoro-1-decyl hex-5-ynoate (F-9). Micelles of PxF9 in water with a core of F-9-segments and a PNIPAM Corona were detected by dynamic light scattering and by H-1 and F-19 NMR spectroscopy below the LCST. Just below the LCST, the PNIPAM chains start to collapse onto the F-9 core followed by aggregation of several collapsed micelles to large particles in the range of approximate to 110 nm. The F-9 segments shifted the LCST to lower temperatures when comparing PxN3 with PxF9. The existence of micelles in PxF9 solutions also improved the reversibility of the LCST behavior as measured by DSC.