Facile anionic synthesis of well-defined block copolymers with pendent triphenylamine and ethynylpyridine for nonvolatile memory device applications with high performances

Abstract

The sequential block copolymerization of 4,4′-vinylphenyl-N,N-bis(4-tert-butylphenyl)benzenamine (A) with 2-(2-(4-vinylphenyl)ethynyl)pyridine (B) was simply carried out using only potassium naphthalenide (K-Naph) as an initiator without any additives in tetrahydrofuran (THF) at −78 °C. The well-defined functional block copolymers containing A block as an electron donor and B block as a weak electron acceptor had predictable molecular weights (Mn = 8,800–14,500 g/mol) and narrow molecular weight distributions (Mw/Mn = 1.09–1.10). The bicontinuous microphase-separated film morphology of the precisely synthesized poly(B-b-A-b-B) (PBAB) with 0.71 of fpoly(A), formed by thermal annealing at 230 °C for 9 h, was expected to be a potential active layer for nonvolatile memory device applications. Indium tin oxide (ITO)/PBAB/aluminum (Al) memory devices with an 8 × 8 cross-bar array structure exhibited nonvolatile resistive switching characteristics. The memory devices showed reliable memory performance in terms of ON/OFF ratios of ∼104, endurance cycles and retention time, and statistical data with regard to cumulative probability of the switching currents and threshold voltage distribution. Filamentary conduction mechanism was proposed to explain the switching of PBAB-based memory devices. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2625-2632