Derivatives of poly(acrylic acid) hydrophobically modified with hydrocarbon group (PH) and both hydrocarbon and fluorocarbon groups (PHF) were synthesized and the association of these copolymers with nonionic surfactant Np7.5 in 0.1M NaCl aqueous solutions was investigated. Microdomains formed in the system of PHF/Np7.5 consist of both hydrocarbon (HC) and fluorocarbon (FC) groups, which is similar to Winnik's mixed model (Kujawa, P. C.; Goh, C. E.; Calvet, D.; Winnik, F. M. Macromolecules 2001, 34, 6387). The hybrid structure of FC and HC groups on the polysoap backbone was proposed to interpret why the miscibility between FC and HC groups was improved. The effect of salt and Np7.5 on PHF and PH solutions was carried out and compared. When the concentration of Np7.5 reaches 0.1 wt % in 0.3 wt % polymer solution especially, physical network junctions become greatly stabilized. (C) 2004 Wiley Periodicals, Inc.