A new functional polyfluorene derivative containing quinoline skeleton and quarternary ammonium groups(QAGs)modified side chains(PFPQ)was synthesized and characterized.The multimodal antimicrobial effect toward Gram-negative E.coli.was achieved by the dark toxicity resulting from quinoline skeleton,and QAGs and light toxicity resulting from reactive oxygen species(ROS)produced by the main backbone of PFPQ under white light.