Freeze-Burn: Fabrication of Porous Carbon Networks via Polymer-Templated Rapid Thermal Annealing

Porous carbons are a valued class of materials widely applied from CO₂ capture to energy storage, but existing fabrication methods are tedious and require multiple steps. We introduce “freeze-burn” as a simple method for creating porous carbon networks by polymer-templated rapid thermal annealing (> 50 °C/sec). This technique leverages thermally induced phase separation for templating and fixes the templated structure by instantaneous polymer degradation. As a model system, particles of reduced graphene oxide were mixed with a polystyrene/poly(vinyl methyl ether) blend to probe the resulting morphologies. We determined that the dependence of macropore formation on particle loading and annealing ramp rate is captured by a single parameter, glass transition temperature, which is indicative of polymer mobility. Without changing the template composition or processing conditions, we demonstrated the applicability of freeze-burn to other carbon materials, such as graphene oxide, carbon black, carbon nanopowder, and carbon nanotubes. This method was improved with a carbonizable polyacrylonitrile-based blend system to generate nanopores and improve the mechanical integrity of prepared porous networks for supercapacitor applications. We anticipate this work to inspire simple, scalable approaches for creating porous materials.