Shape transformations of protein-like copolymer globules

Area of Science:

• Polymer Science
• Materials Science
• Physical Chemistry

Background:

• Amphiphilic multi-block-copolymers form complex structures in selective solvents.
• The interplay between insoluble core-forming blocks and soluble shell-forming blocks dictates globule morphology.
• Understanding these morphologies is crucial for designing advanced materials.

Purpose of the Study:

• To theoretically investigate the shapes of globules formed by amphiphilic multi-block-copolymers.
• To analyze the conditions leading to non-spherical shapes and surface pattern formation.
• To elucidate the different finger morphologies and their formation kinetics.

Main Methods:

• Theoretical analysis of globule shapes based on copolymer composition (H-units and P-blocks).
• Consideration of effective shell tension and shell bending energy relative to core elastic energy.
• Investigation of nucleation and growth processes for finger formation kinetics.

Main Results:

• Globules become non-spherical (prolate or oblate) when effective shell tension is sufficiently low, depending on energy balances.
• Prediction of surface pattern formation, including knobs, beads, cylindrical fingers, and thorn-like fingers.
• Finger formation is a nucleation and growth process; thorn-like fingers characterize metastable regimes with high activation energy.

Conclusions:

• Copolymer globule shape is tunable by adjusting shell tension and bending energy.
• Surface patterning, particularly finger formation, is a key phenomenon accompanying shape transitions.
• The study provides universal predictions for experimental validation in polymer self-assembly.