With the electronic products move towards to flexibility, miniaturisation and high frequency, conductive polymer composites (CPCs) with ultra-low thickness, outstanding electromagnetic interference (EMI) shielding effectiveness (SE) and excellent mechanical property are urgently needed. In this work, silver fractal dendrite/polyvinylidene fluoride (AgFD/PVDF) composite films featured with double structures (defined as two-step films) were fabricated by depositing an AgFD layer followed by the incorporating of PVDF. Thanks to the 3D fractal structures of AgFDs and highly efficient conductive network, the as-prepared two-step films exhibit high electrical conductivity of 4.18 × 10⁴ S·m⁻¹ at only 10 wt% AgFD loading and about 4.18 × 10⁵ S·m⁻¹ at 40 wt% loading. The excellent electrically conductive property endows the two-step films to achieve remarkable EMI SE of 46.8 dB in X-band and 42.7 dB in Ka-band at 10 wt% loading with thickness of 27 μm, and 83.3 and 105.0 dB with thickness of 33 μm as the AgFD loading up to 40 wt%, respectively. The two-step films also show high near-field EMI SE values of 46.9 ∼ 61.4 dB, which fully meets the practical commercial requirements. Additionally, the two-step films possess high flexibility and mechanical strength. Considering the outstanding electrically conductive, EMI shielding performances and excellent mechanical property, the two-step composite films present a huge potential for practical applications as high-efficient EMI protection.

随着电子产品向柔性化、小型化和高频化方向发展，迫切需要具有超薄厚度、出色的电磁干扰（EMI）屏蔽效果（SE）和优异的机械性能的导电聚合物复合材料（CPC）。在这项工作中，通过沉积 AgFD 层，然后加入 PVDF，制备了具有双重结构的银分形枝晶/聚偏二氟乙烯 (AgFD/PVDF) 复合薄膜（定义为两步薄膜）。由于 AgFD 的 3D 分形结构和高效的导电网络，所制备的两步膜仅在 10 wt% AgFD 负载和约 4.18 × 10 ⁵ S时表现出 4.18 × 10 ⁴ S·m ^-1的高电导率·m ^-1在 40 wt% 的负载下。优异的导电性能使两步薄膜在 10 wt% 负载下的 X 波段和 Ka 波段的 EMI SE 分别为 46.8 dB 和 42.7 dB，厚度为 27 μm，厚度为 33，分别为 83.3 和 105.0 dB μm 作为 AgFD 的负载量分别高达 40 wt%。两步膜还表现出较高的近场 EMI SE 值，达到 46.9 ∼ 61.4 dB，完全满足实际商业需求。此外，两步膜具有高柔韧性和机械强度。考虑到出色的导电、EMI屏蔽性能和优异的机械性能，两步复合膜作为高效EMI保护的实际应用具有巨大的潜力。