The synthesis of amphiphilic lipid-polyoxazoline based on copolymers (CO-POx(n)) with narrow distribution has been achieved via cationic ring-opening polymerization of 2-methyl-2-oxazoline (MOx). Lipid-macroinitiator (COTs) was obtained from commercial castor oil (CO), a widely renewable agricultural resource. CO-POX(n) with various length segments was synthesized from a macroinitiator COTs in order to investigate the effect of the length of the hydrophilic segment on the solution behaviour of the nonionic polymer surfactants CO-POx(n). The results showed that the critical micelle concentration increased with the increase of POx content and inversely surface tension decreased. The average size of aggregates of these structures suggested the formation of vesicles or nonspherical micelles. Star-shaped morphology of CO-POx(n) in solid state has also been observed using environmental scanning electron microscopy (ESEM). Additionally energy dispersive X-ray (EDX) analysis demonstrated the presence of POx block in the concentric stripes of the texture. (C) 2009 Elsevier Ltd. All rights reserved.