J. Phys. Chem. B 2008, 112, 8879–8883
8879
Wormlike Morphology Formation and Stabilization of “Pluronic P123” Micelles by Solubilization of Pentaerythritol Tetraacrylate Petar Petrov,*,‡,† Jiayin Yuan,‡ Krassimira Yoncheva,§ Axel H. E. Mu¨ller,‡ and Christo B. Tsvetanov† Institute of Polymers, Bulgarian Academy of Sciences, Akad. G. BoncheV 103A, Sofia, Bulgaria, Makromolekulare Chemie II, UniVersita¨t Bayreuth, Naturwissenschaften II (NW II), Bayreuth, Germany, and Department of Pharmaceutical Technology, Faculty of Pharmacy, Sofia UniVersity St. Kliment Ohridski, 2 DunaV Str., 1000 Sofia, Bulgaria ReceiVed: January 28, 2008; ReVised Manuscript ReceiVed: May 23, 2008
A transition from spherical to wormlike micelles of a poly(ethylene oxide)20-block-poly(propylene oxide)70block-poly(ethylene oxide)20 triblock copolymer Pluronic P123 induced by solubilization of a tetrafuctional monomer, Pentaerythritol tetraacrylate (PETA), in aqueous media has been studied. The wormlike micelles shape was locked by UV cross-linking of PETA within the micelles resulting in stabilized polymeric micelles (SPMs). The stability of SPMs in a good solvent for both polyether blocks like THF, and upon dilution below the critical micelle concentration (CMC) of P123 in water was confirmed by dynamic light scattering (DLS) and scanning force microscopy (SFM). Formation of cadmium sulfide (CdS) nanoparticles within the wormlike SPMs was carried out via the reduction of Cd2+ with NaS and analyzed by transmission electron microscopy (TEM) and UV-vis absorption measurements. A stable water-dispersible hybrid system consisting of CdS quantum dots embedded into the wormlike SPMs was obtained. Introduction Poly(ethylene oxide)-block-poly(propylene oxide)-blockpoly(ethylene oxide) (PEO-b-PPO-b-PEO) triblock copolymers are the most widely studied and commercially important amphiphilic block copolymers.1,2 These copolymers are commercially available surfactants (Pluronics, Synperonics, Poloxamers), whose molecular weight and PEO/PPO composition ratio vary within a wide range.1,2 The properties of these materials in aqueous media have been extensively studied and reviewed.1–11 At low temperature (
