Competition between side-chain interactions dictates 2D polymer stacking order

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Two-dimensional polymers (2DPs) are advanced materials with tunable properties.
• Understanding the factors influencing 2DPs stacking is crucial for optimizing their performance.
• The role of pore-confined species in dictating 2DP structural integrity requires further investigation.

Purpose of the Study:

• To investigate how varying amounts of zwitterions within 2DP pores affect material crystallinity and porosity.
• To elucidate the interplay between zwitterion loading, electrostatic forces, and alkyl chain interactions in directing 2DP stacking.
• To establish structure-property relationships for zwitterion-modified 2DPs.

Main Methods:

• Synthesis of 2DPs with controlled zwitterion incorporation.
• Characterization of 2DP crystallinity and porosity using techniques such as X-ray diffraction and gas adsorption.
• Analysis of the electrostatic and steric interactions governing 2DP assembly.

Main Results:

• High loadings of zwitterions within 2DP pores were found to consistently decrease the quality of the 2DP materials.
• A competitive mechanism between zwitterion-induced electrostatic disruption and alkyl chain stabilization was identified as the primary determinant of 2DP stacking.
• The composition of the polymer side chains significantly influenced the resulting 2DP crystallinity and porosity.

Conclusions:

• Zwitterion incorporation, particularly at high concentrations, negatively impacts 2DP structural quality and properties.
• The stacking behavior of 2DPs is sensitive to the balance of forces between pore-confined species and polymer side chains.
• Tailoring side chain chemistry is essential for controlling 2DP stacking and achieving desired material characteristics.