Non-equilibrium thermal annealing of a polymer blend in bilayer settings for complex micro/nano-patterning

Abstract

Fast morphological evolution of polymer blend dictated by underlying polymer thin film upon rapid thermal annealing at high temperature.

Janus micro‐thread to micro‐nanodroplets using dynamic contact line lithography

“…PMMA has the most prominent Raman peak at 2957 cm À1 which is featured by the vibration of C-H stretching. 3 This is observed only for all the as-deposited samples (Figure 3a,d,g) and the samples after washing with cyclohexane (Figure 3b,e,h). On the other hand, PS demonstrates three of its characteristic peaks between 3200 and 2800 cm À1 .…”

“…The precise location of the component polymers and the composition of the threads or connected droplets was further confirmed at each stage by Raman spectroscopy (Figure 3). PMMA has the most prominent Raman peak at 2957 cm −1 which is featured by the vibration of C–H stretching 3 . This is observed only for all the as‐deposited samples (Figure 3a,d,g) and the samples after washing with cyclohexane (Figure 3b,e,h).…”

“…This suggests two things about the morphology of the polymer structures: first, there are patches of PS and PMMA rich thin layers within the droplets (as the bulk of the materials is washed off separately by cyclohexane and acetic acid), and second, the underlayer structures consist of the nanodroplets of PS surrounded by PMMA rim similar to which is reported earlier for relatively thicker films. 3 As the percentage of the PS increased to 75%, apparently a twin droplet made of one relatively bigger PS (width $472 nm) and one smaller PMMA droplet (width $236 nm) (Figure 6g-i), was formed and both the droplets were covered by a thin layer of PS sheet. The PS droplet was deposited first in front of the PMMA droplet.…”

“…Predominantly, instability of thin-film along with the external perturbations such as electric field, [29][30][31][32] temperature, 3 or solvent assisted dewetting, 33,34 and so forth. engender micro/nanostructures in soft films.…”

“…This bulk phase separation of such polymer blend may turn into stable microphase separation in presence of the corresponding block copolymer due to the surfactant‐like behavior of the copolymer. When geometrically confined into a thin film, the polymer blend alone, 2 or in combination with their corresponding copolymer, 3 self assembles into fascinating micro/nano morphologies. Polymeric phase‐separation‐induced morphological evolution has been extensively investigated over the last few years 4–9 .…”