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Abstract Conventional topochemical photopolymerization reactions occur exclusively in precisely-engineered photoactive crystalline states, which often produces high-insoluble polymers. To mitigate this, here, we report the mechanoactivation of photostable styryldipyrylium-based monomers, which results in their amorphization-enabled solid-state photopolymerization and produces soluble and processable amorphous polymers. A combination of solid-state nuclear magnetic resonance, X-ray diffraction, and absorption/fluorescence spectroscopy reveals the crucial role of a mechanically-disordered monomer phase in yielding polymers via photo-induced [2 + 2] cycloaddition reaction. Hence, mechanoactivation and amorphization can expand the scope of topochemical polymerization conditions to open up opportunities for generating polymers that are otherwise difficult to synthesize and analyze.
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This content will become publicly available on November 1, 2026
Topochemical Photopolymerization above the Bulk Melting Temperature in Noncovalent Monolayers on Graphite
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 Ea= 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, t0.5does 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.
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- Award ID(s):
- 2108966
- PAR ID:
- 10649554
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Small
- Volume:
- 21
- Issue:
- 45
- ISSN:
- 1613-6810
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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