Solvent vapor annealing of block copolymer thin films can produce a range of morphologies different from the equilibrium bulk morphology. By systematically varying the flow rate of two different solvent vapors (toluene and n-heptane) and an inert gas, phase maps showing the morphology versus vapor pressure of the solvents were constructed for 45 kg/mol polystyrene-block-polydimethylsiloxane diblock copolymer films of different thicknesses. The final morphology was correlated with the swelling of the block copolymer and homopolymer films and the solvent vapor annealing conditions. Self-consistent field theory is used to model the effects of solvent swelling. These results provide a framework for predicting the range of morphologies available under different solvent vapor conditions, which is important in lithographic applications where precise control of morphology and critical dimensions are essential.

As practical interest in flexible/or wearable power-conversion devices increases, the demand for high-performance alternatives to thermoelectric (TE) generators based on brittle inorganic materials is growing. Herein, we propose a flexible and ultralight TE generator (TEG) based on carbon nanotube yarn (CNTY) with excellent TE performance. The as-prepared CNTY shows a superior electrical conductivity of 3147 S/cm due to increased longitudinal carrier mobility derived from a highly aligned structure. Our TEG is innovative in that the CNTY acts as multifunctions in the same device. The CNTY is alternatively doped into n- and p-types using polyethylenimine and FeCl, respectively. The highly conductive CNTY between the doped regions is used as electrodes to minimize the circuit resistance, thereby forming an all-carbon TEG without additional metal deposition. A flexible TEG based on 60 pairs of n- and p-doped CNTY shows the maximum power density of 10.85 and 697 μW/g at temperature differences of 5 and 40 K, respectively, which are the highest values among reported TEGs based on flexible materials. We believe that the strategy proposed here to improve the power density of flexible TEG by introducing highly aligned CNTY and designing a device without metal electrodes shows great potential for the flexible/or wearable power-conversion devices.

A perpendicular orientation of high-aspect-ratio polystyrene-block-polydimethylsiloxane (PS-b-PDMS) cylindrical and lamellar PDMS microdomains was achieved by solvent annealing and then slowly drying thick PS-b-PDMS films. Perpendicularly oriented microdomains occurred throughout the film thickness, except at the air interface, where a layer of inplane microdomains formed due to the surface energy difference between PS and PDMS. In contrast, thermal annealing produced in-plane orientation throughout the film thickness. The solvent-annealed perpendicular orientation was observed for cylindrical morphology PS-b-PDMS of 16 and 45 kg/mol, where PDMS is the minority block, and lamellar PS-b-PDMS of 43 kg/ mol. To obtain fully perpendicular microdomain patterns, a nonselective high-powered 450 W CF 4 /O 2 reactive ion etching process was performed to remove the top layer of the films. Substrate patterning using electron beam lithography produced local registration of 17 nm period hexagonal cylinder patterns.

Sub-10 nm Graphene Nanoribbon Arrays are fabricated over large areas by etching CVD-grown graphene. A mask is used made by the directed self-assembly of a cylindrical PS-b-PDMS block copolymer under solvent annealing guided by a removable template. The optimized solvent annealing process, surface-modified removable polymeric templates, and high Flory-Huggins interaction parameters of the block copolymer enable a highly aligned array of nanoribbons with low line edge roughness to be formed. This leads to a higher on/off ratio and stronger temperature dependence of the current for nanoribbon FETs, and a photocurrent which is 30 times larger compared to unpatterned graphene.