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Dynamics of bridge-loop transformation in a membrane with mixed monolayer/bilayer structures
Yan-Ling Yang1, Min-Yi Chen, Heng-Kwong Tsao
1Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan 106, Republic of China. yjsheng@ntu.edu.tw.
Physical Chemistry Chemical Physics : PCCP
|February 17, 2018
Summary
ABA triblock copolymers form planar membranes with coexisting I-shape and U-shape conformations. Increased immiscibility enhances membrane thickness and mechanical strength but reduces permeability.
Area of Science:
- Polymer Science
- Materials Science
- Soft Matter Physics
Background:
- ABA triblock copolymers in selective solvents typically form bilayer or monolayer membranes.
- This study investigates non-ideal membrane formation by these copolymers.
Purpose of the Study:
- To explore the coexistence of bridge (I-shape) and loop (U-shape) conformations in ABA triblock copolymer membranes.
- To analyze the relaxation dynamics and equilibrium properties of these polymer conformations.
- To investigate the impact of A-B block immiscibility on membrane properties.
Main Methods:
- Monitoring non-equilibrium and equilibrium relaxation dynamics of polymer conformations.
- Investigating geometrical, mechanical, and transport properties of the membranes.
- Analyzing the influence of varying A-B block immiscibility.
Main Results:
- Both I-shape and U-shape conformations coexist in planar membranes.
- Non-equilibrium relaxation time increases with initial composition and A-B block immiscibility.
- Membrane thickness and mechanical moduli (stretching and bending) increase with immiscibility.
- Lateral polymer diffusivity is unaffected by immiscibility, but membrane permeability decreases significantly.
Conclusions:
- Membrane properties are strongly influenced by the immiscibility of A and B blocks in ABA triblock copolymers.
- Increased immiscibility leads to thicker, stiffer membranes with reduced permeability.
- The observed constant ratio of bending to stretching moduli and thickness suggests a universal scaling behavior.
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