Dynamic silicone networks have been synthesized with boronic esters to form readily reprocessable polymers which can dissolve back to monomer under appropriate solvent conditions. The relation between network density and relaxation times is investigated, and the densest meshes reveal the highest activation energy for flow and thus reprocessing. We also examine these networks over a 200 C window which reveals a breakdown of the canonical Arrhenius behavior observed in vitrimeric materials. Five different metrics for measuring the relaxation times are compared to understand the relationship between different testing protocols. Next, we prepared thin coatings from the PDMS networks to test their hydrophobicity and abilty to retain function in response to various damage mechanisms.  Unlike the most popular strategy using perfluoro-compounds (PFC) with a mechanically robust matrix to form a composite for coating protection, our materials are fluorine-free. We demonstrate durable hydrophobicity and superhydrophobicity with nanoscale-thick PFC-free polydimethylsiloxane vitrimers that are self-healing due to the exchange of network strands after scratching, cutting, and indenting. We also show that silicone vitrimers can be deposited through scalable dip-coating on a variety of substrates. This work shows the promise of vitrimer coatings in achieving long-term durable hydrophobicity for applications such as heat transfer, water harvesting, and desalination which can improve our energy and water usage.

PDMS dynamic networks for recyclable thermosets and durable hydrophobic coatings

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.