A number of perfluorooctyl-modified poly(oxyethylene)s (FQPEOs) of molar masses of approximately 2000 and 4000 were synthesised using a two-step procedure: (a) preparation of PEO precursors bearing tertiary amino groups (NPEOs) and (b) their quaternisation with perfluorooctyl iodide to obtain one-ended (FQEn), telechelic (FQEnFQ) or PEO modified with a C8F17-group in the mid of the polyether chain (EnFQEn). F-Q is abbreviation of the C8F17-group attached to a PEO chain (E-n) through a quaternary ammonium group. The aqueous solution properties of FQPEOs were studied by viscosity measurements at 25 degreesC. The cationic charge affects the association ability of the F-Q group and the one-ended FQEn behaves like PEO modified with a C6F13-group through urethane linkage. Temperature induced interactions in aqueous mixtures of FQPEOs with poly(N-isopropylacrylamide) (PNIPAM) were studied by turbidity and theological measurements. In the semi-dilute regime, the aqueous polymer mixtures exhibit a large viscosity enhancement upon heating as soon as the temperature reaches 35 degreesC. In the range from 35 to 40 degreesC the mixtures of PNIPAM with FQEn and E50FQE50 form gels with viscoelastic response. The solution of PNIPAM mixed with the telechelic FQE100FQ reveals shear-thickening at 35 and 40 degreesC.