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Abstract While studies of surface‐templated topochemical reactions often focus on the central role of monomer ordering, the reactions themselves frequently require Ångström‐scale dynamics to form new bonds. Here, it is showed that elevated temperatures increase the topochemical reaction efficiency of 10,12‐tricosadiynoic acid (TCDA), a widely utilized commercial diacetylene monomer, assembled on highly oriented graphite (HOPG) substrates. Up to ≈45 °C, Arrhenius temperature dependence is observed for the reaction, with E_a= 5.9 kcal mol⁻¹(0.26 eV), consistent with limitations imposed by the propagation step of the reaction, which requires monomer dynamics within the lattice. At higher temperatures, t_0.5does not continue to decrease. However, the number average degree of polymerization continues to increase, from 97 at 5 °C to 248 at 65 °C, and the number density of polymers formed per incident photon increases by 6–13‐fold at elevated temperatures (45–65 °C) in comparison with polymerization at 5 °C. Together, these changes in the on‐surface reaction greatly increase molecular sheet integrity, resulting in a 10‐fold increase in the efficiency of a covalent mesh‐forming reaction that transfers TCDA sheets to soft polydimethylsiloxane. 

Abstract Lamellar phases of alkyldiacetylenes in which the alkyl chains lie parallel to the substrate represent a straightforward means 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 set the 1‐nm functional patterns embedded in the monolayer, making it important to understand structure–function relationships for these on‐surface reactions. Polymerization can be observed for certain monomers at the single‐polymer scale using scanning probe microscopy. However, substantial restrictions on the systems that can be effectively characterized have limited utility. Here, using a new multi‐scale approach, we identify a large, previously unreported difference in polymerization efficiency between the two most widely used commercial diynoic acids. We further identify a core design principle for maximizing polymerization efficiency in these on‐surface reactions, generating a new monomer that also exhibits enhanced polymerization efficiency. 

Control over the surface chemistry of elastomers such as polydimethylsiloxane (PDMS) is important for many applications. However, achieving nanostructured chemical control on amorphous material interfaces below the length scale of substrate heterogeneity is not straightforward, and can be particularly difficult to decouple from changes in network structure that are required for certain applications (e.g., variation of elastic modulus for cell culture). We have recently reported a new method for precisely structured surface functionalization of PDMS and other soft materials, which displays high densities of ligands directly on the material surface, maximizing steric accessibility. Here, we systematically examine structural factors in the PDMS components (e.g., base and cross-linker structures) that impact efficiency of the interfacial reaction that leads to surface functionalization. Applying this understanding, we demonstrate routes for generating equivalent nanometer-scale functional patterns on PDMS with elastic moduli from 0.013 to 1.4 MPa, establishing a foundation for use in applications such as cell culture. 

Hydrogels are broadly used in applications where polymer materials must interface with biology. The hydrogel network is amorphous, with substantial heterogeneity on length scales up to hundreds of nanometers, in some cases raising challenges for applications that would benefit from highly structured interactions with biomolecules. Here, we show that it is possible to generate ordered patterns of functional groups on polyacrylamide hydrogel surfaces. We demonstrate that when linear patterns of amines are transferred to polyacrylamide, they pattern interactions with DNA at the interface, a capability of potential importance for preconcentration in chromatographic applications, as well as for the development of nanostructured hybrid materials and supports for cell culture.