Thin-film morphologies of block copolymers with nanoparticles

Abstract

Diblock copolymers (BCP) show phase separation on mesoscopic length scales and form ordered morphologies in both bulk and thin films, the latter resulting in nanostructured surfaces. Morphologies in thin films are strongly influenced by film parameters, the ratio of film thickness and bulk domain spacing. Laterally structured polymer surfaces may serve as templates for controlled assembly of nanoparticles. We investigated BCP of poly(n-pentyl methacrylate) and poly(methyl methacrylate) which show bulk morphologies of stacked lamellae or hexagonally packed cylinders. Thin films were investigated by atomic force microscopy and grazing-incidence small-angle X-ray scattering. For film thicknesses f well below d bulk , standing cylinder morphologies were observed in appropriate molar ratios, while film thicknesses around and larger than d bulk resulted in cylinders arranged parallel to surface. To alter and/or improve the morphology also in presence of different nanoparticles (NP: silica, gold), solvent vapour annealing (SVA) was applied. The BCP morphology usually remains unchanged but periodicities change depending on type and amount of incorporated NPs. It was found that silica clusters enlarge lateral distances of cylinders, whereas Au NPs reduce it. The effect of SVA is weak. The quality of morphology is slightly improved by SVA and lateral distances remain constant or are slightly reduced.

Segregation of Maghemite Nanoparticles within Symmetric Diblock Copolymer and Triblock Terpolymer Patterns under Solvent Vapor Annealing

“…In contrast with the di/BCP hosts, the time efficiency in the tri/BCP solvent annealing process plays a more prominent role [47]. The film formation process can be divided in two stages.…”

“…In contrast with the di/BCP hosts, the time efficiency in the tri/BCP solvent annealing process plays a more prominent role [47].The film formation process can be divided in two stages. Firstly, the nanoparticles emerge on the top of the surface (for the first 96 h) and then the swelling of the blocks takes place due to the chemical affinity of the PS-grafted NPs with the PS domain.…”

Effects of nanoparticles on phase morphology in thin films of phase-separated diblock copolymers

“…This behaviour is different from the result found by stepwise off-line treatment of pure DiBCP films with TEOS, followed by treatment with H 2 O/HCl vapour (Jehnichen et al ., 2015). In this method of NP generation, a rather weak decrease of the d -values was found.…”

“…Apart from direct mixing of pre-synthesized NP with DiBCP in an appropriate solvent (here THF), in the case of SiO x the in situ sol–gel process in solution was applied to generate SiO x NP (Näther, 2010). This allowed comparing thin films with SiO x prepared by moderate treatment of the polymer films with precursor-containing vapours in different steps (Jehnichen et al ., 2015).…”

“…X-ray reflectometry (XRR) for pre-characterization, grazing-incidence small-angle X-ray scattering (GISAXS, for details about the method see, e.g. Müller-Buschbaum, 2003), and atomic force microscopy (AFM) experiments were applied on dip-coated thin films with film thicknesses to <40 nm, which should guarantee standing cylinders in relation to the DiBCP used (Werner et al , 2011; Horechyy et al , 2014; Jehnichen et al , 2015). By combination of the methods the influence of the type of NP, as well as the film preparation method on the morphology of the DiBCP was evaluated.…”