(544c) Plenty of Room at the Interface: Multi-Scale Insights into Nm-Resolution Polymer Pattern Chemistries

Striped phases of alkyldiacetylenes (sPDA), in which alkyl chains lie parallel to the substrate, represent a straightforward approach for scalable 1-nm-resolution interfacial patterning. This capability has the potential for substantial impacts in nanoscale electronics, energy conversion, and biomaterials design. Polymerization is required to lock in the 1-nm functional patterns within the monolayer, making it important to understand structure–function relationships governing these on-surface reactions. Moreover, our recent work has demonstrated the feasibility of transferring polymerized sPDA from rigid crystalline substrates onto soft materials, such as polydimethylsiloxane (PDMS) and polyacrylamide, via crosslinking reactions. The covalent transfer of sub-10-nm striped patterns enriches the functionality of the biocompatible surfaces. To control the sPDA pattern transfer at interfaces, it is crucial to understand the dependency of interfacial crosslinking reactions on the efficiency of sPDA polymerization.

Here, we employed a multi-scale characterization approach, combining scanning probe microscopy for single-polymer scale and fluorescence-based metrics at microscale, to investigate sPDA polymerization and crosslinking pattern transfer for carboxylic and amine striped phases. Remarkably, we noticed that minor alterations in sPDA molecular structure, which have negligible impact on reaction kinetics in bulk systems, significantly influenced polymerization rates and crosslinking transfer efficiency within these surface-confined striped phases. Moreover, Integration of single-molecule scanning and microscopic fluorescence readouts allowed us to develop a probabilistic model that describes the transfer process in terms of sPDA–PDMS crosslinking reaction efficiency and number of reactions required for transfer from hard surface to soft materials. Furthermore, we illustrated that transferred 1-nm-width functional patterns on soft materials can be used to direct both adsorption of CdSe nanocrystals with alkyl ligand shells and covalent reactions with fluorescent dyes, highlighting the utility of functional patterning on the soft surface.