Ultralow k covalent organic frameworks enabling high fidelity signal transmission and high temperature electromechanical sensing

As integrated circuits have developed towards the direction of complexity and miniaturization, there is an urgent need for low dielectric constant materials to effectively realize high-fidelity signal transmission. However, there remains a challenge to achieve ultralow dielectric constant and ultralow dielectric loss over a wide temperature range, not to mention having excellent thermal conductivity and processability concurrently. We herein prepare dual-linker freestanding covalent organic framework films with tailorable fluorine content via interfacial polymerization. The covalent organic framework possesses an ultralow dielectric constant (1.25 at 1 kHz, ≈1.2 at 6 G band), ultralow dielectric loss (0.0015 at 1 kHz) with a thermal conductivity of 0.48 Wm-1K-1. We show high-fidelity signal transmission based on the large-sized (>15 cm2) COF films, far exceeding the most commercially available polyimide-based printed circuit board. In addition, the covalent organic framework also features excellent electret properties, which allows for active high-temperature electromechanical sensing. The electrode nanogenerator maintains 90% of the output voltage at 120 °C, outperforming the traditional fluorinated ethylene propylene electret. Collectively, this work paves the way for scalable application of ultralow dielectric constant covalent organic framework thin films in signal transmission and electromechanical sensing.

Tetrafluorophenylene-Containing Vinylbenzyl Ether-Terminated Oligo(2,6-dimethyl-1,4-phenylene ether) with Better Thermal, Dielectric, and Flame-Retardant Properties for Application in High-Frequency Communication

In an integrated circuit, signal propagation loss is proportional to the frequency, dissipation factor (D _f), and square root of dielectric constant (D _k). The loss becomes obvious as we move to high-frequency communication. Therefore, a polymer having low D _k and D _f is critical for copper-clad laminates at higher frequencies. For this purpose, a 4-vinylbenzyl ether phenoxy-2,3,5,6-tetrafluorophenylene-terminated OPE (VT-OPE) resin was synthesized and its properties were compared with the thermoset of commercial OPE-2St resin. The thermoset of VT-OPE shows a higher T _g (242 vs 229 °C), a relatively high cross-linking density (1.59 vs 1.41 mmole cm^-3), a lower coefficient of thermal expansion (55 vs 76 ppm/°C), better dielectric characteristic at 10 GHz (D _k values of 2.58 vs 2.75, D _f values of 0.005 vs 0.006), lower water absorption (0.135 vs 0.312 wt %), and better flame retardancy (UL-94 VTM-0 vs VTM-1 with dropping seriously) than the thermoset of OPE-2St. To verify the practicability of VT-OPE for copper-clad laminate, a laboratory process was also performed to prepare a copper-clad laminate, which shows a high peeling strength with copper foil (5.5 lb/in), high thermal reliability with a solder dipping test at 288 °C (>600 s), and the time for delamination of the laminate in thermal mechanical analysis (TMA) at 288 °C is over 60 min.

Diphenoquinones Redux

Benzoquinones can undergo reversible reductions and are attractive candidates for use as active materials in green carbon-based batteries. Related compounds of potential utility include 4,4'-diphenoquinones, which have extended quinonoid structures with two carbonyl groups in different rings. Diphenoquinones are a poorly explored class of compounds, but a wide variety can be synthesized, isolated, crystallized, and fully characterized. Experimental and computational approaches have established that typical 4,4'-diphenoquinones have nearly planar cores in which two cyclohexadienone rings are joined by an unusually long interannular C═C bond. Derivatives unsubstituted at the 3,3',5,5'-positions react readily by hydration, dimerization, and other processes. Association of diphenoquinones in the solid state normally produces chains or sheets held together by multiple C-H···O interactions, giving structures that differ markedly from those of the corresponding 4,4'-dihydroxybiphenyls. Electrochemical studies in solution and in the solid state show that diphenoquinones are reduced rapidly and reversibly at potentials higher than those of analogous benzoquinones. Together, these results help bring diphenoquinones into the mainstream of modern chemistry and provide a foundation for developing redox-active derivatives for use in carbon-based electrochemical devices.

Perfluorocyclobutyl-containing transparent polyimides with low dielectric constant and low dielectric loss

The combination of loose chain packing and high fluoro content endows PFCB-containing polyimides with excellent optical transparency and dielectric properties.

A bio-based low dielectric material at a high frequency derived from resveratrol

An efficient strategy to design and synthesize a low dielectric material at a high frequency of 5 GHz derived from renewable resveratrol.