One-pot route to fine-tuned hypercrosslinked polymer solid acid catalysts

Abstract

Highly sulfonated polymers are promising heterogeneous catalysts due to their excellent chemical and thermal stability, as well as the possibility of employing low-cost synthesis routes. However, their production is time consuming and control of their chemical and physical properties is often difficult. We present sulfonated hypercrosslinked polymers produced using chlorosulfonic acid as a dual polymerisation catalyst and sulfonation agent, consolidating a conventional two-step process into a one-pot reaction. Network synthesis time is reduced from 5-6 days to <24 hours, while significantly lowering or eliminating the requirement of some reagents. These sulfonated networks display superior acid site densities and porosities compared to conventional equivalents and excellent control over polymer properties is achieved. The polymers are employed as heterogeneous acid catalysts in the hydrolysis of cyclohexyl acetate. Therein, it is shown that fine-tuning polymer properties has a dramatic effect on their catalytic performance, allowing the identification of key catalyst properties.