Multistructural Network Design Enables Polybenzoxazine to Achieve Low-Loss-Grade Super-High-Frequency Dielectric Properties and High Glass Transition Temperatures

Abstract

An original design strategy for the preparation of thermosetting resins with both super-high-frequency low dielectric constant (k) and low dielectric loss (f) as well as high glass transition temperature (T g) values is presented. The key to this design strategy is incorporating a bulky group and reactive furan ring to increase the free volume and the cross-linking density, respectively. The formed multistructural networks (relatively dense near furan rings and relatively loose near bulky groups) are beneficial not only for lowering k values but also for maintaining high T gs of main-chain benzoxazine copolymers. More importantly, the optimized copolymers possess low f values (≤0.008) under 5 and 10 GHz, satisfying the requirement of super-high-frequency communications. The correlations between the free volume and thermal and dielectric properties are also discussed to understand the synergistic mechanism. The work opens a new route for the structural design and preparation of super-high-frequency low dielectric functional polymeric materials.

Solvent-free Synthesis of Alkynyl-Based Biobased Benzoxazine Resins with Excellent Heat Resistance

“…We characterized the structure of the benzoxazine monomer by the characteristic peaks of the methylene and alkynyl groups on the oxazine ring on the spectrum. As shown in Figure a,b, the characteristic peaks of O–CH 2 –N on the oxazine ring of E-apa and M-apa appeared at 5.30 and 5.25 ppm, respectively, − and the characteristic peaks of Ar–CH 2 –N on the oxazine ring of appeared at 4.51 and 4.64 ppm, respectively. − The characteristic peaks of alkynyl hydrogen on E-apa and M-apa appear at 2.95 and 3.02 ppm, respectively. As shown in Figure c,d, the characteristic peaks of O–CH 2 –N on the oxazine ring of E-apa and M-apa appear at 79.20 and 78.87 ppm from the 13 C NMR, respectively, and the characteristic peaks of Ar–CH 2 –N on the oxazine ring appear at 55.83 and 50.88 ppm, respectively.…”

Molecular-level insight into the low-k properties and regulatory mechanisms of polybenzoxazines

“…Benzoxazole, tert-butyl, alicyclic rings, and long alkyl chains have been applied to the molecular design of low-k polybenzoxazine according to the theoretical guidance of reducing molecular polarizability and dipole density. [11][12][13][14][15] Among them, alicyclic rings can effectively reduce the dielectric constant of polymers due to their small isotropic polarizability tensors. 16 The rigid alicyclic ring can also prevent molecular stacking and increase the free volume of polymers.…”

Synthesis of a Novel Bifunctional Epoxy Double-Decker Silsesquioxane: Improvement of the Thermal Stability and Dielectric Properties of Polybenzoxazine

“…These advantages have attracted the attention of researchers. The molecular structure design of PBZ is very flexible, and various structures of polybenzoxazines have been developed for a wide range of applications, including polymer coatings [ 5 , 6 , 7 ], flame retardants [ 8 , 9 , 10 ], electromagnetic shielding [ 11 , 12 ], and microelectronics [ 1 , 13 , 14 , 15 ]. Nevertheless, PBZ thermosets also have some drawbacks that limit its application.…”