A trilayered composite membrane with a pore-tunable interlayer for liquid management in wound dressing applications

Effective wound dressings must simultaneously drain excess exudate and maintain a moist microenvironment; however, facile fabrication of dressings enabling such bidirectional fluid management remains challenging. Herein, we report a structurally robust trilayered composite membrane engineered via sequential electrospinning and hot-pressing, featuring a pore-tunable interlayer for precise liquid manipulation. The hierarchical architecture comprises a hydrophilic cotton layer, an electrospun polyurethane (PU) adhesive interlayer, and a hydrophobic PU/ethylcellulose (EP) layer, where the interlayer serves as the critical regulator of liquid behavior. By tuning the porosity to range from 36.3 % to less than 1 % through controlling the electrospinning duration of the PU adhesive layer (30–90 min) and hot-pressing temperature (60–80 °C), we achieved synergistic bidirectional fluid control: efficient exudate drainage performance coupled with controllable backflow propensity. Specifically, the water droplets penetrated from the hydrophobic to the hydrophilic side within 7 s, and additionally, larger porosity correlated with enhanced backflow, thereby achieving balanced moisture retention. Systematic in vitro investigations revealed correlations between fabrication parameters and the membrane's morphological, wettability, air permeability (73.0 to 3.3 mm/s), and liquid management properties. Moreover, the trilayered composite membrane possessed great cytocompatibility (approximately 99 %) and maintained skin humidity above 44 %. This work presents a straightforward strategy for designing functional polymer composites with tunable bidirectional fluid transport, highlighting the trilayered membrane's promising application potential in advanced wound care based on in vitro evaluations.