Design Rules for Binary Bisamide Gelators: toward Gels with Tailor-Made Structures and Properties.

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Rheology

Background:

• Understanding gelator mixtures is key to designing novel materials.
• Bisamide gelators offer tunable properties based on spacer length.
• Hydrogen bonding interactions influence self-assembly.

Purpose of the Study:

• To establish design rules for binary gelator mixtures.
• To correlate supramolecular assembly patterns with rheological properties.
• To investigate the impact of parity and spacer length on gelator behavior.

Main Methods:

• Synthesis and blending of nBA gelators with varying methylene spacer lengths (n=5-10).
• Analysis of solid-state and gel-state assembly using microscopy and rheological measurements.
• Systematic variation of gelator ratios and parities.

Main Results:

• Binary gelator mixtures exhibit assembly behavior consistent in solid and gel states.
• Co-assembly into fibers or sheets observed for mixtures differing by two methylene units.
• Phase separation occurs in mixtures of different parities or same parity with larger spacer differences.
• Even-even gels (sheets) show higher storage modulus (G') than odd-odd gels (fibers).
• Self-sorting into discrete structures generally decreases G', except for specific cases like (5BA)1(9BA)1.

Conclusions:

• Spacer length and parity critically dictate binary gelator assembly and phase behavior.
• Supramolecular architecture directly influences the rheological properties of the resulting gels.
• Design rules for binary gelator mixtures can be derived from parity and spacer length.