High-temperature polymers with record-high breakdown strength enabled by rationally designed chain-packing behavior in blends

QY Zhang and X Chen and B Zhang and T Zhang and WC Lu and Z Chen and ZY Liu and SH Kim and B Donovan and RJ Warzoha and ED Gomez and J Bernholc and QM Zhang, MATTER, 4, 2448-2459 (2021).

DOI: 10.1016/j.matt.2021.04.026

Polymers with high dielectric breakdown strength (E-b) over a broad temperature range are vital for many applications. The presence of weak points, such as voids and free volume, severely limit the E-b of many high-temperature polymers. Here, we present a general strategy to reduce these weak points by exploiting interchain electrostatic forces in polymer blends. We show that the strong interchain electrostatic interaction between two high-temperature polymers in blends of polyimide (PI) with poly(ether imide) (PEI) yields an extended polymer chain conformation, resulting in dense chain packing and a corresponding decrease in weak spots in the polymers. This leads to a greater than 65% enhancement of E-b at room temperature and 35% enhancement at 200 degrees C. In conjunction with results from blends of Pl/poly(1,4-phenylene ether-sulfone) (PSU) and blends of PEI/PSU, we show that this previously unexplored molecular engineering strategy is efficient and straightforward in minimizing weak points in dielectric polymers.

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