σ Phase Formed in Conformationally Asymmetric AB-Type Block Copolymers

Area of Science:

• Polymer Science
• Materials Science
• Computational Chemistry

Background:

• Block copolymers exhibit diverse self-assembled morphologies.
• Understanding phase stability is crucial for designing advanced materials.
• Conformational and architectural asymmetry influence phase behavior.

Purpose of the Study:

• Investigate the stability of spherical phases in asymmetric AB diblock and miktoarm block copolymers.
• Unify conformational and architectural asymmetry using a single parameter, ε.
• Determine the conditions for the stability of sigma and A15 phases.

Main Methods:

• Self-consistent field theory (SCFT) simulations.
• Analysis of phase diagrams based on conformational asymmetry degree (ε).
• Evaluation of interfacial energy and domain formation.

Main Results:

• The sigma phase becomes stable and its region expands with increasing ε.
• The A15 phase emerges for large conformational asymmetry (ε = 9), situated between sigma and hexagonal phases.
• The A15 phase offers more favorable interfacial energy, leading to larger domains and stability under stronger segregation.

Conclusions:

• Conformational asymmetry significantly dictates the stability and emergence of complex spherical phases in block copolymers.
• The unified parameter ε effectively captures the influence of asymmetry on phase behavior.
• SCFT provides a powerful tool for predicting phase diagrams and understanding structure-property relationships in complex copolymers.