ORIGINAL CONTRIBUTION PI-b-PMMA diblock copolymers: nanostructure development in thin films and nanostructuring of thermosetting epoxy systems I. Barandiaran & D. Katsigiannopoulos & E. Grana & A. Avgeropoulos & A. Eceiza & G. Kortaberria Received: 7 March 2013 / Revised: 10 April 2013 / Accepted: 11 April 2013 / Published online: 21 April 2013 # Springer-Verlag Berlin Heidelberg 2013 Abstract Poly(isoprene-block-methyl methacrylate) (PI-b- PMMA) block copolymers with different block ratios have been used to generate nanostructures both in thin films and by nanostructuring a thermosetting epoxy system. Obtained morphologies have been analyzed in terms of atomic force microscopy. The nanostructuring of thin films was carried out by thermal and solvent vapor annealing, in which the copolymer films were exposed to acetone vapors, selective solvent for methyl methacrylate (PMMA) block. By solvent vapor annealing thin films of both copolymers self-assembled into a hexagonally packed cylindrical morphology. Thermal annealing was carried out above the glass transition tempera- ture of both blocks, obtaining worm-like and lamellar morphol- ogies, depending on the block ratio. One of the copolymers has also been used for nanostructuring an epoxy thermosetting system. Morphologies consisting of spherical-shaped PI domains dispersed in a continuous epoxy matrix in which PMMA remained miscible were obtained, independently of the copolymer amount. Keywords PI-b-PMMA . Diblock copolymer . Nanostructuring . Thermal annealing . Solvent vapor annealing Introduction Diblock copolymers consist of two sequences of monomer units with different chemical composition that are covalent- ly bonded. Due to the thermodynamic incompatibility be- tween blocks, they can self-assemble in a wide variety of nanostructures, covalent linkage among blocks preventing the phase separation at macroscopic scale [1–3]. This self- assembling capability has increased the scientific interest in block copolymers during the last years [4–7]. Morphologies of self-assembled block copolymers de- pend on several parameters such as copolymer composition (f), Flory–Huggins interaction parameter among both blocks (χ), and polymerization degree of the copolymer (N). Most common morphologies obtained for diblock copolymers either in bulk or in thin films are spheres, cylinders, gyroids, and lamellas [8–11], depending on the aforementioned parameters or thermal treatments and solvents. The self-assembly of block copolymer thin films has become increasingly important, as they could be used as templates for nanoparticle deposition, nanolithography, or nanopatterned materials [4, 12–26]. Different techniques are being used for nanostructuring block copolymer thin films: thermal annealing [15, 16], control of interfacial interaction [17–19], solvent vapor annealing (SVA) [20–26], electric field [27, 28], chemical prepatterning [29, 30], graphoepitaxy [31, 32], or epitaxial growth [33, 34]. The aim of thermal annealing is to increase the mobility of polymer chains, favoring the self-assembly and the ordering and alignment of nanodomains [15]. For nanostructuring a thin film by SVA, solvent election is of crucial importance. The solubility of both blocks in the solvent determines generated morphologies [20–26]. The solubility of a nonpolar polymer in a solvent is determined by the Flory–Huggins I. Barandiaran : A. Eceiza : G. Kortaberria (*) ‘Materials+Technologies’ Group, Escuela Politécnica, Dept of Chemical & Environmental Engineering, Universidad País Vasco/Euskal Herriko Unibertsitatea, Pza. Europa 1, 20018 Donostia-San Sebastián, Spain e-mail: galder.cortaberria@ehu.es D. Katsigiannopoulos : E. Grana : A. Avgeropoulos Department of Materials Science and Engineering, University Campus-Dourouti, University of Ioannina, 45110 Ioannina, Greece Colloid Polym Sci (2013) 291:2173–2180 DOI 10.1007/s00396-013-2961-6