The C36 Laves phase in diblock polymer melts.

Area of Science:

• Materials Science
• Polymer Physics
• Soft Matter Physics

Background:

• Laves phases (C14, C15) are common micelle packing structures in soft matter.
• The related C36 Laves phase, with alternating C14/C15 layers, has not been observed in diblock polymer systems.

Purpose of the Study:

• Investigate the absence of the C36 Laves phase in diblock polymers.
• Relate C36 morphology and energetics to other known mesophases using self-consistent field theory.

Main Methods:

• Self-consistent field theory simulations.
• Analysis of morphology and free energy in diblock polymer systems.
• Case studies: AB diblock/A homopolymer blends and neat AB diblock melts.

Main Results:

• C36 free energy is a near-perfect bisector of C14 and C15 free energies across all studied systems.
• This energetic symmetry arises from the intermediate packing structure of C36.
• C14 and C15 phases exhibit nearly identical micelle morphologies and degenerate free energies.

Conclusions:

• The intrinsic free energy symmetry explains the absence of C36 in flexible diblock polymers.
• C14 and C15 phases are thermodynamically favored over C36 due to facile mass transfer.
• C36 is not expected to form in flexible diblock polymer systems.