Enhanced Ordering in Thin Block Copolymer Films Through a Change of Polymer Molecular Mass and the Resultant Thermodynamic Driving Force for Ordering

Published

March 25, 2015

Author(s)

Jack F. Douglas, Xiaohua Zhang, Alamgir Karim

Abstract

We demonstrate that an increase of the molecular mass of a cylinder-forming PS-PMMA block copolymer (BCP), and thus the Flory-Huggins interaction strength N, allows us to robustly form surface patterns having the technologically interesting perpendicular cylinder BCP orientation with respect to the substrate. We also observe a gradual transition in the surface area of our BCP films that have a parallel cylinder orientation with increasing BCP molecular mass. Recent work has shown that decreasing the annealing temperature in a lamellae forming PS-PMMA BCP polymer leads to progressive standing up of the lamellae perpendicular to the substrate if the surface is at first treated with nanoparticles to make the boundary interaction more neutral, demonstrating that increasing the BCP segregation strength can enhance both the quality and extent of BCP ordering in thin films. Tuning the polymer mass also allows for a precise tuning of the in-plane BCP cylinder pattern wavelength, and the height modulation of the BCP as the height modulation varies in direct proportion to  as in late stage phase blend films near critical blend composition.

Citation

RSC Advances

Pub Type

Journals

Keywords

block copolymer, cylinder morphology, perpendicular alignment, molecular mass, flipping transition

Citation

Douglas, J. , Zhang, X. and Karim, A. (2015), Enhanced Ordering in Thin Block Copolymer Films Through a Change of Polymer Molecular Mass and the Resultant Thermodynamic Driving Force for Ordering, RSC Advances (Accessed October 18, 2025)