Research Article Received: 2 September 2012 Revised: 5 October 2012 Accepted: 21 November 2012 Published online in Wiley Online Library: (wileyonlinelibrary.com) DOI 10.1002/pi.4456 Self-assembled nanostructures: preparation, characterization, thermal, optical and morphological characteristics of amphiphilic diblock copolymers based on poly(2-hydroxyethyl methacrylate-block-N-phenylmaleimide) Guadalupe del C Pizarro, a* Oscar G Marambio, a Manuel Jeria-Orell, a Daniela T Vald ´ es a and Kurt E Geckeler b,c* Abstract A series of well-defined amphiphilic poly[(2-hydroxyethyl methacrylate)-block-(N-phenylmaleimide)] diblock copolymers containing hydrophilic and hydrophobic blocks of different lengths were synthesized by atom transfer radical polymerization. The properties of the diblock copolymers and their ability to form large compound spherical micelles are described. Their optical, morphological and thermal properties and self-assembled structure were also investigated. The chemical structure and composition of these copolymers have been characterized by elemental analysis, Fourier transform infrared, 1 H NMR, UV–visible and fluorescence spectroscopy, and size exclusion chromatography. Furthermore, the self-assembly behavior of these copolymers was investigated by transmission electron microscopy and dynamic light scattering, which indicated that the amphiphilic diblock copolymer can self-assemble into micelles, depending on the length of both blocks in the copolymers. These diblock copolymers gave rise to a variety of microstructures, from spherical micelles, hexagonal cylinders to lamellar phases. c  2013 Society of Chemical Industry Keywords: controlled radical polymerization; diblock copolymers; amphiphilic block copolymers; self-assembly; thermal behavior INTRODUCTION In recent decades, widespread attention has been given to the self- assembly of amphiphilic block copolymers in solution because of the potential applications of the resulting products in nanoscience and technology, e.g. as an ideal platform for fabricating novel nanostructured materials. 1 – 3 An important example of such self- organizing materials are the amphiphilic diblock copolymers, which consist of two or more polymers chemically bonded to each other. These diblock copolymers spontaneously self-assemble into periodic nanostructures (e.g., spherical, cylindrical, bi-continuous, lamellar), the size and morphology of which can be easily con- trolled by varying molecular weight and composition. These self-assembled domains are monodisperse and have dimensions of the order of nanometers; the morphology and domain size are gen- erally controlled by adjusting each block’s length and molecular mass. 4 Thus, block copolymers are formed by the covalent union of two or more polymer chains that are generally incompatible, giving rise to a great variety of microstructures as well as solid states in dis- solution. Due to the microphase separation associated with block copolymers, the morphology can be tuned from spherical micelles to hexagonal cylinders to lamellae, or inverses of these phases, by continuously changing the length of the blocks. These materials are very attractive for use in the synthesis of functional nanostructures because their length and spatial organization can be controlled through the block copolymer morphology. 3 – 5 In the last decade, important advances in radical polymerization reactions have led to the development of synthetic methods that eliminate (or diminish, ∗ Correspondence to: Guadalupe del C. Pizarro, Department of Chemistry, Technological Metropolitan University, J. P. Alessandri 1242, Santiago, Chile. E-mail: gpizarro@utem.cl, pizarroguadalupe048@gmail.com. Kurt E. Geckeler, Laboratory of Applied Macromolecular Chemistry, School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, South Korea. E-mail: keg@gist.ac.kr a Department of Chemistry, Technological Metropolitan University, J.P. Alessandri 1242, Santiago, Chile b Department of Nanobio Materials and Electronics (WCU), Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712, South Korea c Laboratory of Applied Macromolecular Chemistry, School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, South Korea Polym Int (2013) www.soci.org c  2013 Society of Chemical Industry