Three random copolymers comprised pendant styrene and 4-(1-pyrenyl)-styrene (PyS) moieties in different molar ratios (21.4:1 (P1), 3.9:1 (P2), and 1.4:1 (P3)) were synthesized and employed as charge storage polymeric electret for nonvolatile organic field-effect transistor (OFET) memory application. The impact of varying the molar ratio in side-chain electron-donating pyrene moieties on the thermal, optical, photophysical, electrochemical, and electrical properties of the resulting pendant copolymers was evaluated to establish structure-property relationship. The OFET memory with P3 electret layer exhibits a largest memory window of 41.8 V, long retention time of 10(4) s with memory ratio of 10(5), and stable reversibility of at least 100 cycles due to enhanced field-induced holes trapping ability from higher PyS composition ratio. Therefore, polymer electret with pendant functional moieties shows potential for use as trapping layer in OFET memory devices. (C) 2015 Wiley Periodicals, Inc.