Investigating microstructure evolution in block copolymer membranes

Area of Science:

• Materials Science
• Polymer Science
• Chemical Engineering

Background:

• Block copolymer self-assembly and nonsolvent-induced phase separation (SNIPS) are crucial for integral-asymmetric membrane fabrication.
• Numerous formulation and processing parameters in SNIPS hinder reliable high-performance membrane construction.

Purpose of the Study:

• To model the SNIPS process using dynamical self-consistent field theory.
• To investigate the impact of solvent selectivity, nonsolvent selectivity, initial film composition, and glass transition composition on membrane morphology.

Main Methods:

• Application of dynamical self-consistent field theory.
• Analysis of parameter effects on micelle structure and membrane matrix formation.
• Examination of surface layer order and layer connectivity.

Main Results:

• Identified critical roles of solvent selectivity and polymer concentration on micelle structure.
• Demonstrated that surface layer order and layer connectivity are sensitive to all studied parameters.
• Revealed nontrivial challenges in preserving surface layer integrity and ensuring layer connection.

Conclusions:

• Parameter sensitivity in SNIPS necessitates careful control for successful block copolymer membrane fabrication.
• Insights gained can guide the rational design and optimization of integral-asymmetric membranes.
• Provides a theoretical framework for predicting and controlling membrane morphology.