Copolymerization mechanism of bismaleimide and cyanate Ester resins: Effect of naphthalene structures

With the development of aerospace and printed circuit board (PCB) industries, the thermal performance requirements for BT resins are continuously increasing. In this paper, naphthalene structure was introduced into the common BT resin system to improve the heat resistance of BT resin, and the effect of the naphthalene structure on the curing mechanism was investigated. Comprehensive studies on the copolymerization and curing mechanisms of the N,N '-(4,4 '-methylenediphenyl)bismaleimide/bisphenol A cyanate resin (BDM/BADCy) system and the N,N '-(4,4 '-methylenediphenyl)bismaleimide/bisphenol A cyanate/naphthalene cyanate (BDM/BADCy/ DNCy) system were carried out without the use of a catalyst, by using Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), Pyrolysis Gas Chromatography-Mass Spectrometry (Py-GC-MS), Fourier transform infrared (FTIR), and two-dimensional Infrared (2D-FTIR) analytical techniques. The experimental results demonstrated that the cyanate ester (CE) and bismaleimide (BMI) initially copolymerized, predominantly leading to the formation of a pyrimidine structure. Subsequently, in the later stage of the reaction, CE underwent homopolymerization to form a triazine ring structure. The incorporation of the naphthalene ring conspicuously enhanced the reactivity, effectively lowered the curing temperature, expedited the onset of the copolymerization reaction, and promotes the formation of more copolymers. Moreover, due to the rigid nature of the naphthalene ring and the increased cross-linking density, the heat resistance of cured BT resin was consequently improved. This study provides valuable insights for the fabrication of high-performance BT resins with naphthalene ring structures.