Adjusting the Proportion of Electron-Withdrawing Groups in a Graft Functional Polymer for Multilevel Memory Performance.

A polymer containing aldehyde active groups (PVB) was synthesized by atom transfer radical polymerization (ATRP), acting as a polymer precursor to graft a functional moiety via nucleophilic addition reaction. DHI (2-(1,5-dimethyl-hexyl)-6-hydrazino-benzo[de]isoquinoline-1,3-dione) and NPH (nitrophenyl hydrazine) groups, which contain naphthalimides that act as narrow traps and nitro groups that act as deep traps, were anchored onto the PVB at different ratios. A series of graft polymers were obtained and named PVB-DHI, PVB-DHI4 -NPH, PVB-DHI-NPH4 , and PVB-NPH. The chemical composition of the polymers was analyzed by (1) H-NMR spectroscopy and X-ray photoelectron spectroscopy (XPS). Memory devices were prepared from the polymers, and I-V characteristics were measured to determine the performance. By adjusting the ratio of different electron acceptors (DHI and NPH) to 4:1, ternary memory behavior was achieved. The relationship between memory behavior of PVB-DHIx NPHy and acceptor groups as well as their conduction mechanism were studied in detail.