Bilayer-folded lamellar mesophase induced by random polymer sequence.

Area of Science:

• Polymer Science and Engineering
• Materials Science
• Soft Matter Physics

Background:

• Randomness in polymers is typically associated with macroscopic homogeneity and local heterogeneity, seemingly distant from ordered structures.
• Understanding the self-assembly behavior of random copolymers is crucial for designing advanced materials with tailored properties.

Purpose of the Study:

• To investigate the spontaneous emergence of order in binary random copolymers during self-assembly.
• To characterize the novel liquid crystalline mesophase formed and its unique structural features.

Main Methods:

• Construction of a binary random copolymer with a Bernoullian distribution of hydrophilic and hydrophobic side chains on a linear backbone.
• Self-assembly of the copolymer in an aqueous environment.
• Characterization of the resulting mesophase using techniques sensitive to structural hierarchy and optical properties.

Main Results:

• Spontaneous formation of periodic order from a binary random copolymer with over 10^15 possible chain sequences.
• Emergence of a novel liquid crystalline mesophase termed 'bilayer-folded lamellae' due to sequence matching problems and curvature stabilization.
• Observation of anisotropically alignable birefringence and structural hierarchy across multiple length scales in the self-assembled hydrogel.

Conclusions:

• Periodic order can spontaneously arise from seemingly random polymer sequences during self-assembly.
• The discovered bilayer-folded lamellae represent a new class of liquid crystalline mesophases with potential applications in advanced materials.
• The findings provide new insights into the relationship between sequence heterogeneity, self-assembly, and emergent order in polymers.