Triblock copolymers with a poly(N-iso-Pr acrylamide) (PNIPAm) central block and short cationic polymeric ionic liq. (PIL) endblocks were synthesized via ATRP. The chem. different blocks interact with each other and thus the presence and length of the PIL blocks affected the aggregation behavior of the thermoresponsive polymers at temps. below and above the cloud point.The PIL-PNIPAm interactions decreased the enthalpy of phase sepn. at the cloud point not only in the case of block copolymers but also in mixts. of corresponding homopolymers. However, the decrease in Î”H was not directly proportional to the no. of IL units present. This indicates that the IL units do not solely complex with the NIPAm units, but the PILs also interact with each other. The morphol. of the aggregates is different with different lengths of the PIL blocks. At higher concns. the block copolymers formed stable gels upon heating due to the phase transition of PNIPAm and the solubilizing effect of the PIL blocks.