Structural investigation of thin diblock copolymer films using time-of-flight grazing-incidence small-angle neutron scattering

Abstract

The depth‐dependent morphology of the microphase separation structure in thin block copolymer films is examined using non‐destructive time‐of‐flight grazing‐incidence small‐angle neutron scattering. The structure of a cylinder‐forming diblock copolymer, polystyrene(deuterated)‐block‐polyisoprene, in contact with either a low‐ or a high‐energy substrate surface is investigated. A systematic identification of the components of the polymer film at different depths is achieved by utilizing the material characteristic Yoneda peak. For the polymer film attached to the low‐surface‐energy aminosilane‐coated substrate, a morphology transition from lamellar at the substrate–polymer interface, via perforated lamellar in the film bulk, to an ill‐defined structure at the polymer–air interface is observed. This phase transition along the film normal is due to the competition between the surface‐induced morphological changes and the stable cylindrical bulk morphology of the diblock copolymer. In contrast, on the high‐energy surface no pronounced ordering is found for the applied conditions.

Distributions of Deuterated Polystyrene Chains in Perforated Layers of Blend Films of a Symmetric Polystyrene-block-poly(methyl methacrylate)

“…Note that instead of truncation rods with q ⊥ -intensity elongation, the off-axis signals associated with perforations only appear as diffraction spots. This result indicates that the diffraction spots mainly result from a transmission effect, which has been detailed in previous studies. , …”

“…This result indicates that the diffraction spots mainly result from a transmission effect, which has been detailed in previous studies. 64,65 In contrast, the GISANS 2D pattern of the thick films annealed at 230 °C reveals another scattering feature. As Figure 5c shows, the meridional and equatorial directions show two intense on-axis diffraction spots.…”

Advanced grazing-incidence techniques for modern soft-matter materials analysis

“…So far, TOF-GISANS has been used to study, for example, the dewetting of thin polymer films (Mü ller-Buschbaum et al, 2009), the infiltration of conjugated conducting polymers into titania network structures for application in hybrid solar cells (Kaune et al, 2010;Rawolle et al, 2013), the micro-phase separation structure inside diblock copolymer films (Busch et al, 2011;Metwalli et al, 2011;Mü ller-Buschbaum et al, 2014) and the self-assembly of diblock copolymer-maghemite nanoparticle hybrid thin films (Yao et al, 2014). At the moment, neutron sources have limited neutron flux which spreads into a broad wavelength band, requiring long counting times of several hours to achieve reasonable statistics, thus limiting the use of TOF-GISANS.…”

Debye–Scherrer rings from block copolymer films with powder-like order

“…However, switching to neutrons (GISANS instead of GISAXS) changes the situation. For neutrons, the substrate is most likely transparent, and the scattering in the transmission hemisphere can also be observed and used for data analysis (Metwalli et al, 2011). As we will show in this article, the transmitted intensity of these scattering patterns increases with the angle of incidence, i , and the dynamic effects become more and more negligible, so the analysis can be simplified significantly.…”