Programming Chain Distribution of Branched Polymers via Bond Exchange Reactions

Branched chain isomerizable network allows polymers to be programmed into a variety of branched chain distribution (Pi) and branch chain uniformity (α) that are challenging to characterize experimentally, leading to difficulties in establishing structure–property relationships. We employ coarse-grained molecular dynamics (CGMD) simulations to demonstrate the equivalence principle for bond exchange reactions (BERs) and propose a theoretical model to describe the Pi and α dynamics under BERs. The theoretical model accurately characterizes the intricate time evolution of Pi and α by relying solely on BER rates and initial configurations, enabling precise control of Pi and α. Furthermore, a concise equation is proposed to describe the Pi and α of the BER equilibrium state, revealing the geometric distribution of branched chain, which overthrows the conventional understanding that it obeys a uniform distribution. Finally, taking the example of α modulating the toughness, we illustrate how the proposed theoretical model allows for the establishment of structure–property relationships. Overall, this work addresses the challenge of experimentally characterizing Pi and α, and introduces a novel research paradigm for establishing structure–property relationships.