In Situ Grazing-Incidence SAXS Investigation of Thermal-Induced Self-Assembly Process of PS-b-PMMA Films Deposited on Surface-Modified Substrate

Abstract

Directed self-assembly of block copolymers (BCPs) is widely investigated for its potential application in surface patterning. The self-assembly kinetics of BCP based on modified layers is the key to realizing structural control for obtaining highly ordered lamellar grains. In this study, morphological evolution of PS-b-PMMA films during the thermal-induced self-assembly process was investigated via the in situ grazing-incidence small-angle X-ray scattering (GISAXS) technique. In the first heating stage, reorientation of lamellar grains occurred as the temperature increased above the glass transition temperature. Then, a fast increase in the lamellar repeat period L 0 was observed, which is considered as a phase separation process. Whereas the size of the lamellar grain ξ was observed to have rapidly increased in the stage wherein the temperature was held at 230 °C, the L 0 was almost constant. This result indicates that the formation of ordered structure in PS-b-PMMA films was mainly determined by two periods: phase separation of block molecules followed by growth of grains in the nanodomain. In addition, it was interesting that the better-order nanodomains were obtained with thermal annealing at a faster heating rate. These findings suggest that accomplishing ordered structure control in a large area could be realized via the design of a proper heating profile.

A Designed Template Removal Method for Obtaining Mesoporous Films with Highly Ordered Structure by Rapid Thermal Processing Technique

“…To estimate the scale of ordered domain quantitatively, the domain size of the mesoporous films under different treatments was obtained using the Scherrer equation ξ = 2π k /Δ q , where Δ q is the fwhm of 10 peaks and k is a dimensionless shape factor with a value of 0.89. , The peak position and fwhm obtained from GISAXS profiles and the calculated results are displayed in Table and Figure .…”

Enhancing Efficiency and Photo-Stability of Organic Solar Cells via Vertical Phase Separation Morphology Induced by Surface Modification of PEDOT:PSS with Star-Shaped Benzene-Based DFTAB Additive

“…An incident angle α i of 0.15° (near the critical angle) was applied in the GIWAXS/GISAXS experiment, thus providing a global and strong (averaged) scattering signal for the sample. 4 The GIWAXS/GISAXS Data analysis. The structural information of blend films such as the period of arrangement and lamellar stacking spacing is obtained via the Bragg equation, as well as the crystal coherence length (CCL) can be obtained from the Scherrer formula, 6 and the specific expressions of the Bragg equation and Scherrer formula are as follows:…”