Fire-retardant, self-extinguishing multiblock poly(esterimide)s/graphene composites with segregated structure for electromagnetic interference shielding

• An innovative strategy was demonstrated to fabricate segregated composites in low-melt-viscosity polymeric systems. • All-aromatic multiblock poly(esterimide)s/multilayer graphene composites with segregated structures were fabricated. • Exceptional EMI shielding efficiency is achieved with a reflection-dominant mechanism. • These composites exhibit high thermal stability and outstanding flame retardancy. Segregated conductive composites based on all-aromatic liquid crystal polymers (LCPs) are ideal material candidates for electromagnetic interference (EMI) shielding. However, grand challenges still remain for constructing segregated LCP composites due to the sharp viscosity decrease at crystal-to-nematic transition temperature and the very low melt-viscosity of LCPs. Herein, conductive composites based on all-aromatic multiblock poly(esterimide)s (BPEI) and multilayer graphene (MLG) with well-defined segregated structure were fabricated by solid-state compression molding with a broad processing window, which was enabled by the appropriate viscosity at the rubbery state originating from the two very distinct glass transition temperatures of the as-synthesized BPEI block copolymer. The segregated BPEI/MLG composite with 5.0 wt% MLG loading achieves an ultrahigh electrical conductivity of 313.5 S/m and a high EMI shielding effectiveness of 62.2 dB at a thickness of only 2.3 mm. Moreover, the segregated BPEI/MLG composites exhibit high thermal stability and outstanding flame retardancy.