Changing the memory behaviors from volatile to nonvolatile via end-capping of hyperbranched polyimides with polycyclic arenes

Three aromatics endcapped hyperbranched polyimides (HBPIs), with triphenylamine derivative (A3) as core, 4,4-(hexafluoroisopropylidene)diphthalic anhydride as B2 monomer, phthalic anhydride (PA), 1,8-Naphthalic anhydride (NA) and 3,4-perylenedicarboxylic anhydride (PDA) as endcapping reagents are explored as polymer memory materials. All these HBPIs showed excellent solubility in various organic solutions. Tunable memory characteristics from volatile to nonvolatile were obtained by adjusting the endcapping groups. Compared to PA endcapped HBPI, NA and PDA endcapped HBPIs exhibited enhanced nonvolatile memory behaviors with switch voltages low to 0.8 V and 1.0 V, and outstanding thermal stability with 5% weight loss temperatures reaching up to 533 °C and 554 °C, respectively. Such superior performance can be attributed to the introduced polycyclic arenes end-groups, which leads to stronger conjugation intensity, better hole transport ability and higher charge separation stability.