Frontal Polymerization‐Enabled 3D Printing of Recyclable High‐Performance Carbon Fiber Reinforced Polymers

Abstract

Abstract Thermoset composites often face a challenging trade‐off between recyclability and high performance. In this study, an innovative closed‐loop manufacturing approach that integrates frontal ring‐opening metathesis polymerization (FROMP) with 3D printing to produce fully recyclable carbon fiber‐reinforced polymers (c‐CFRPs) is presented. A self‐propagating FROMP‐enabled direct ink writing (DIW) printing technology is developed, enabling in situ curing within seconds. This breakthrough eliminates the need for post‐processing and reduces energy consumption by two orders of magnitude compared to traditional autoclave methods. By copolymerizing dicyclopentadiene (DCPD) with a commercial spiroacetal monomer (≤3 wt.%), acid‐degradable resins that retain the tensile strength of conventional thermosets are introduced while allowing for matrix depolymerization under mild conditions. The DCPD‐based c‐CFRPs demonstrate remarkable tensile strengths of up to 817 MPa and glass transition temperatures exceeding 160 °C. In a significant advancement, the recovered carbon fibers retain their pristine morphology and over 95% of their original mechanical properties, enabling repeated recycling without performance loss. Additionally, recovered oligomers can be repolymerized into new resins, further enhancing sustainability. This work presents a groundbreaking solution for high‐performance composite manufacturing, addressing critical energy and waste challenges in the thermoset industry.