Generalized Model for Inhibitor-Modulated 2D Polymer Growth to Understand the Controlled Synthesis of Covalent Organic Frameworks.

Two-dimensional (2D) polymers, also known as 2D covalent organic frameworks (COFs), are increasingly finding use in applications such as membrane separations, catalysis, and energy conversion. Current research is focused on the development of new synthesis routes for COFs and obtaining a mechanistic understanding of the growth process to control it in a better manner. In this regard, synthesis methods such as reversible polycondensation termination use monofunctional inhibitor species to achieve a controlled growth rate for COFs. However, so far, the role of the inhibitors in modulating the kinetics of COF growth is inadequately understood. In this work, inspired by the Mayo-Lewis framework, we develop a generalized kinetic model to describe the synthesis of a 2D COF monolayer. Our model involves six parameters corresponding to the rate constants of attachment and detachment of monomer and inhibitor species, as well as enhancement factors that quantify the effect of the local coordination environment of the attaching/detaching species on the reaction kinetics. We measure the inhibitor concentration-dependent growth kinetics of the COF experimentally and fit our model to experimental yield data, with the same parameters working across multiple inhibitor concentrations. As the growth process is inherently stochastic, we use this knowledge to develop a comprehensive kinetic Monte Carlo (KMC) simulation of 2D COF synthesis, demonstrating that scaled rate constants are required in the inherently