Ultra- and high-performance polymers for material extrusion additive manufacturing: Recent advancements, challenges, and optimization perspectives

Material extrusion-based additive manufacturing (MEXAM) has emerged as a transformative technology for ultra-performance polymers (UPPs) and high-performance polymers (HPPs), enabling their use in demanding applications across diverse industries such as aerospace, automotive, medical, and defense. Their high strength-to-weight ratio, heat resistance, chemical stability, and performance retention under harsh conditions perfectly match the high potential of additive manufacturing for cost-effectiveness, flexibility, and adaptability. Among the most studied UPPs/HPPs, Polyimide (PΙ), polyetherketoneketone (PEKK), and polyetheretherketone (PEEK) have gained substantial attention due to their printability and superior functional properties. Despite these advantages, MEXAM of UPPs and HPPs presents considerable challenges. This review provides a comprehensive analysis of the molecular, rheological, thermal, and structural characteristics of UPPs/HPPs and their major composites that influence their printability and performance. A comparative evaluation of their advantages and limitations is presented, along with a discussion on recent advancements in process optimization. Research efforts for the optimization of MEXAM process control parameters were reviewed and interpreted. Furthermore, this work explores the integration of Artificial Intelligence (AI)-assisted optimization strategies to enhance processing efficiency and material properties. This study identifies key research gaps and highlights opportunities for future advancements in the field of MEXAM for UPPs and HPPs.