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Order and Disorder in ABCA' Tetrablock Terpolymers
Madalyn R Radlauer1,2, Akash Arora3, Megan E Matta1
1Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States.
The Journal of Physical Chemistry. B
|November 2, 2020
Summary
Self-assembly of poly(styrene)-block-poly(isoprene)-block-poly(lactide)-block-poly(styrene) (SILS) tetrablock terpolymers was studied. Adding a polystyrene end-block to low-molecular-mass precursors induced disorder, while higher-mass precursors maintained order, aligning with self-consistent field theory predictions.
Area of Science:
- Polymer Science and Engineering
- Materials Science
- Soft Matter Physics
Background:
- Block copolymers exhibit complex self-assembly behavior driven by polymer segment incompatibility.
- Tetrablock terpolymers with an ABCA' architecture present unique self-assembly challenges due to multiple block interactions.
- Understanding self-assembly is crucial for designing advanced materials with tailored morphologies.
Purpose of the Study:
- To investigate the self-assembly of poly(styrene)-block-poly(isoprene)-block-poly(lactide)-block-poly(styrene) (SILS') tetrablock terpolymers.
- To explore the influence of terminal polystyrene chain length on the morphology of SILS' polymers.
- To compare experimental self-assembly results with predictions from self-consistent field theory (SCFT).
Main Methods:
- Synthesis of SILS' tetrablock terpolymers based on varying molar masses of precursor SIL triblock polymers and terminal PS' chains.
- Experimental characterization using transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS).
- Theoretical modeling using self-consistent field theory (SCFT) to predict self-assembly behavior.
Main Results:
- SCFT predicts that adding a terminal PS' chain to low-molar-mass SIL precursors can induce a disordered state.
- Experimental results for low-molar-mass SILS' polymers confirmed a shift from ordered to disordered morphology with increasing PS' chain length.
- Higher-molar-mass SILS' polymers showed microphase separation, with medium-mass polymers maintaining long-range order and higher-mass polymers exhibiting limited order.
Conclusions:
- The addition of terminal polystyrene blocks significantly influences the self-assembly of SILS' tetrablock terpolymers.
- Experimental findings align with SCFT predictions, particularly for lower-molar-mass systems.
- Frustration in accessing well-ordered materials is a key consideration for ABCA'-type polymer self-assembly.
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