Amphiphilic block copolymers of poly(ethylene oxide) and poly(perfluorohexylethyl methacrylate): from synthesis to applications

A new series of amphiphilic di- and triblock copolymers of Poly(ethylene oxide) (PEO) and Poly(perfluorohexylethyl methacrylate) (PFMA) has been synthesized by atom transfer radical polymerization using mono- or bifunctional PEO macroinitiators. Small angle X-ray scattering studies above the melting temperature of the PEO block have revealed a composition dependent ordered morphologies of cubic arrangement of spheres (bcc), hexagonally packed cylinders (hpc) and lamellar microdomains. Crystallization was, however, found to destroy the ordered melt morphology and imposes a layered structure. Self-assembly in aqueous medium was explored by dynamic light scattering (DLS), and TEM. DLS data reveal the formation of small aggregates (micelles) and single chains in diblock copolymer solutions. In triblock copolymer aqueous solution, large clusters were the dominant scatterers in addition to the micelles and single chains. The individual micelles were assumed flower-like micelles having some chains dangling in solution and the large clusters as the loose aggregates formed by the intermicellar connection through bridges. Interfacial behavior and penetration into 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) monolayer by block copolymers at the air/water interface was studied by measuring the surface pressure (pi)-area (A) isotherms in conjunction with infrared reflection absorption spectroscopy. The pi/A isotherms of the block copolymers show pressure regimes corresponding to different conformations of the polymer chains, i.e. a pancake like conformation at low surface coverage, and a brush conformation at high surface pressures. Cytotoxicity of the block copolymers on K562 human erythroleucemia cells reveal that these materials are nontoxic up to a copolymer concentration of 0.2 wt.-%. The interaction of the copolymers with model bilayer membranes was studied by measuring the effect of block copolymers on the zeta-potential value and the size of the liposomes as function of added block copolymer concentration. The encapsulation of a model hydrophobic drug; testosterone undecanoate by the amphiphilic block copolymer micelles by dialysis technique has also been studied.SIGLEAvailable from: http://deposit.ddb.de/cgi-bin/dokserv?idn=972532773 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman