Synergistic Integration of Liquid Crystalline Ordering and Dynamic Networks for Ultrarobust Bismaleimide Vitrimers

ABSTRACT Bismaleimide (BMI) thermosets combine high glass‐transition temperatures and thermal stability but are difficult to reprocess after curing. Here, a liquid‐crystalline bismaleimide vitrimer (LC‐BMIV) was prepared from a biphenyl‐based mesogenic bismaleimide (SBMI) and 2,2′‐diallylbisphenol A (DABA), which provides both allyl curing groups and preinstalled hydroxyl groups. SAXS and WAXS measurements indicate local mesogenic organization without long‐range crystallinity. The stoichiometric network exhibited a glass‐transition temperature of 297.5°C by DSC, a DMA‐derived transition temperature of 304.6°C, and a 5% mass‐loss temperature of 404.0°C. Tensile stress‐relaxation measurements at 310°C–350°C showed continued modulus decay below 100 MPa and yielded an apparent activation energy of 154.34 kJ mol −1 . Because the measurements were performed near and above the α‐transition region, the derived kinetic parameters may include contributions from both segmental relaxation and network rearrangement. Temperature‐dependent reprocessing and gel‐fraction measurements identified 300°C as the most appropriate balance between macroscopic consolidation and preservation of network integrity. Repeated reprocessing largely retained the principal thermal and structural characteristics, although tensile recovery was partial. These results provide a route to reprocessable high‐temperature BMI networks while clarifying the contributions and limitations of mesogenic organization and exchange‐active network chemistry.