Multifunctional compatible waterborne polyurethane microfiber leather with enhanced antibacterial properties via low-content Ag-decorated lignin-hybrid hollow silica nanoparticles

M ultifunctional m icro f iber s ynthetic l eather (MMFL) with antibacterial activity, air permeability, moisture transmission, UV resistance, and mechanical robustness, is highly needed by advanced applications. However, achieving these integrated functionalities often requires complex designs and high filler loadings, leading to aggregation and compromised mechanical performance. Here, we propose a low-filler-content strategy using only 2–5 wt% of silver-decorated l ignin- h ybrid h ollow s ilica sphere s (Ag@LHHSs) in a w aterborne p olyurethane (WPU) to fabricate MMFL with integrated functionalities. The superior performance stems from the synergistic structure-function design of Ag@LHHSs: 1) uniformly distributed Ag n ano p articles (NPs) generate ·OH radicals, providing strong antibacterial efficacy, while simultaneously coordinating with WPU carbonyl/amine groups to enhance interfacial adhesion without compromising mechanical integrity; 2) lignin shell, rich in hydroxyl and sulfonic groups, contributes to UV protection and forms hydrogen bonds with WPU, further improving compatibility; 3) the hollow architecture creates free volume, enhancing breathability and moisture permeability. With only 2–5 wt% Ag@LHHSs, our MMFL achieves antibacterial efficiency of exceeding 99 %, air permeability of 283.4 mm/s (26.0 % higher than neat WPU), and 2 ·24 h water vapor transmission of 7120 g/m 2 (171.1 % improvement), meanwhile maintaining UV resistance and mechanical robustness. This work provides a promising strategy for developing lightweight, low-cost, multifunctional synthetic microfiber leathers via rational nanofiller design and interfacial engineering.