Abstract: The development of miniaturized, flexible, and portable electronic devices has led to an increasing demand for multifunctional flexible films that can provide temperature regulation, electromagnetic interference (EMI) shielding, and thermal management. In this study, a novel hierarchical multifunctional flexible composite film is presented. The first step involves the synthesis of phase change microcapsule (PCMC) latex through in-situ polymerization. Next, PCMC and waterborne polyurethane (WPU) latex were mixed and dried using a binary colloidal approach to produce a flexible composite phase change film (WPU/PCMC) with complete anti-leakage and satisfying melting enthalpy (147.86 J g^-1). To enhance the EMI performance and mechanical strength, a thin layer of antioxidant MXene@poly tannin acid (PTA) was directly sprayed onto the surface of WPU/PCMC, resulting in the WPU/PCMC/MXene@PTA film (WPM). Consequently, the WPM displays exceptional thermal management performance for multiple drives and outstanding EMI performance (56.86 dB), making it an ideal candidate for future multifunctional products.

Key words: Flexibility, Microcapsules, Composite film, Thermal management, EMI shielding