Enhancing ordering dynamics in solvent-annealed block-copolymer films by lithographic hard masks supports

We studied solvent-driven ordering dynamics of block copolymer films supported by a densely cross-linked polymer network designed as organic hard mask (HM) for lithographic fabrications. The ordering of microphase separated domains at low degrees of swelling corresponding to intermediate/strong segregation regimes was found to proceed significantly faster in films on a HM layer as compared to similar block copolymer films on silicon wafers. The ten-fold enhancement of the chain mobility was evident in the dynamics of morphological phase transitions and of related process of terrace-formation on a macroscale, as well as in the degree of long-range lateral order of nanostructures. The effect is independent of the chemical structure and on the volume composition (cylinder-/ lamella-forming) of the block copolymers. In-situ ellipsometric measurements of the swelling behavior revealed a cumulative increase in 1-3 vol. % in solvent up-take by HM-block copolymer bilayer films, so that we suggest other than dilution effect reasons for the observed significant enhancement of the chain mobility in concentrated block copolymer solutions. Another beneficial effect of the HM-support is the suppression of the film dewetting which holds true even for low molecular weight homopolymer polystyrene films at high degrees of swelling. Apart from immediate technological impact in block copolymer-assisted nanolithography, our findings convey novel insight into effects of molecular architecture on polymer-solvent interactions.Comment: This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Macromolecules, copyright \c{opyright} American Chemical Society after peer review. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/ma500561

Diagnostics of Damages in Reinforced Concrete by the Parameters of Electric Response to Mechanical Impact

A method for non-destructive testing of reinforced concrete based on thephenomenon of mechano-electric transformations is proposed in this work. The procedure forassessing damage in concrete is based on the measurement of an electric response to a weakelastic impact. It was found that the moments of crack formation and growth during bendingare accompanied by a significant decrease in the correlation coefficient of the electricresponses spectra and by a stepwise change in spectrum shift (at frequency domain) at whichthe maximum correlation coefficient is observed. It was determined that the increase of energyattenuation coefficient of the electric response can serve as a forerunner of a catastrophicdestruction in concrete. The diagnostic criteria proposed in this work can be used formonitoring the damage processes in reinforced concrete under bending conditions

Doppelgänger in Orhan Pamuk’s The Black Book

This article examines Orhan Pamuk’s The Black Book in connection with the doppelgänger motif in literature. In The Black Book, Galip’s wife Rüya and his cousin Jelal disappear all of a sudden, and the novel narrates Galip’s search for them who remain invisible throughout the novel. There is a conflict between the characters Galip and Jelal, and this article claims that although the two characters are depicted in the novel as Galip and Jelal, Jelal turns out to be the second self or author self of Galip. Thus, the doppelgänger motif will also be associated with authorship.publisher versio

Distortion of a Unit Cell versus Phase Transition to Nonbulk Morphology in Frustrated Films of Cylinder-Forming Polystyrene‑<i>b</i>‑polybutadiene Diblock Copolymers

Dimensions of cylindrical domains and microphase separation behavior in thin films of polystyrene-<i>b</i>-polybutadiene diblock copolymer (SB) are analyzed under fine variation of the surface fields, polymer–polymer interactions, film thickness, and the symmetry of the wetting conditions. In thermally and in solvent annealed films the dimensions of the closest to the substrate cylinders are smaller than both in thicker films and in bulk due to the confinement effect. The related excess of the stretching energy favors a transition to nonbulk perforated lamella morphology in a narrow window of the film thickness, solvent concentration, and annealing temperature. The discussion of the apparent stability/instability of thin film morphologies includes the analysis of molecular architecture, interfacial tensions, and possible influence of dynamic effects

Temperature-Controlled Solvent Vapor Annealing of Thin Block Copolymer Films

Solvent vapor annealing is as an effective and versatile alternative to thermal annealing to equilibrate and control the assembly of polymer chains in thin films. Here, we present scientific and practical aspects of the solvent vapor annealing method, including the discussion of such factors as non-equilibrium conformational states and chain dynamics in thin films in the presence of solvent. Homopolymer and block copolymer films have been used in model studies to evaluate the robustness and the reproducibility of the solvent vapor processing, as well as to assess polymer-solvent interactions under confinement. Advantages of utilizing a well-controlled solvent vapor environment, including practically interesting regimes of weakly saturated vapor leading to poorly swollen states, are discussed. Special focus is given to dual temperature control over the set-up instrumentation and to the potential of solvo-thermal annealing. The evaluated insights into annealing dynamics derived from the studies on block copolymer films can be applied to improve the processing of thin films of crystalline and conjugated polymers as well as polymer composite in confined geometries