Mapping Nanoscale Order-Disorder Transitions to Optimal Topochemical Polymerization Across Alkyl Diacetylene...

Area of Science:

• Materials Science
• Surface Chemistry
• Nanotechnology

Background:

• On-surface reactions in molecular networks are key for nanoscale interface design.
• Achieving efficient bond formation requires balancing molecular layer stability with local dynamics.

Purpose of the Study:

• Develop a framework to identify optimal conditions for topochemical polymerization of diacetylene monolayers on 2D materials.
• Systematically vary H-bonding headgroup chemistry (COOH, OH, NH2) to understand its impact on polymerization efficiency.

Main Methods:

• Temperature-dependent polymerization measurements.
• Atomic force microscopy (AFM), differential scanning calorimetry (DSC).
• Molecular dynamics (MD) simulations.

Main Results:

• Bulk melting temperatures (Tm) were 56°C (TCD-COOH), 51°C (TCD-OH), and 26°C (TCD-NH2).
• Maximum polymerization efficiency (Tmax) occurred near surface disorder or solid-solid transitions, not bulk melting.
• Tmax values were 65°C (TCD-COOH), 45°C (TCD-OH), and 45°C (TCD-NH2).

Conclusions:

• Optimal on-surface reactivity correlates with pre-melting increases in alkyl chain mobility.
• Established a strategy to maximize on-surface topochemical polymerization efficiency.
• Surface-confined structural transitions are critical for controlling polymerization.