In this work, inspired by the structural properties of plant leaves during transpiration, we focused on simulating the pore gradient and the role of liquid transport channels within leaves. We introduced a groundbreaking Janus nanofibrous structure integrating longitudinal channels and horizontal networks to amplify liquid transportation efficiency. This innovative design features a gradient porous structure, constructed via layer-by-layer deposition, comprising a hydrophilic-underwater oleophobic Polyacrylonitrile (PAN) layer, a hydrophobic-underwater oleophilic TPU2 layer, and a middle HNF buffer layer enriched with helical CA/TPU1 nanofibers (the trilayer membrane is termed as PHT membrane). The helical fibers, uniquely achieved through hydrophilic PDA surface modification between polymer components, represent a pioneering approach to directional liquid transportation. Notably, to our knowledge, this integrated structure represents the first of its kind. The pore channels in the fiber membrane's upper, middle, and lower layers generate negative pressure in the thickness direction through asymmetric wettability and porosity, forming an efficient longitudinal water transport path. The horizontal interconnection network of the intermediate buffer absorbing layer effectively reduces the gravitational resistance, further promotes the discharge of water, and achieves more efficient liquid transport. Therefore, this synergy between longitudinal and horizontal channels in the Janus structure significantly enhances liquid transportation efficiency, compared with the wettability gradient Janus membrane. Results show that the PDA-modified three-dimensional helical structure reduces the effective diameter of capillary channels and forms interconnected cellular pathways rather than just vertical porous pathways with straight fibers. This configuration can promote capillary rise, boost moisture absorption by mitigating gravity resistance, and ultimately optimize the DLT performance of Janus fiber membranes. This biomimetic Janus nanofibrous structure with helical nanofibers demonstrates significant potential for application in industrial wastewater treatment, marine oil spill cleanup, and high-end functional garments.
Plant leaves form efficient water transport and vapor diffusion channels during transpiration through the complex pore structures between the upper and lower epidermis, palisade tissue, and spongy layer (Fig. 1a). Although the leaf does not conduct direct directional liquid transport, it achieves anti-gravity water transport from the root to the leaf through transpiration pull and a pore network while promoting water vapor diffusion and gas exchange through air gaps (within the palisade tissue and spongy layer) inside the leaf. This multi-level pore structure supports the longitudinal transport of water (from root to leaf) and facilitates the horizontal distribution of water via lateral pores, ensuring the plant's water balance during drought conditions. Inspired by this natural phenomenon, this study designed an innovative Janus nanofiber membrane that mimics the transpiration mechanism of plant leaves by utilizing pore gradients and liquid transport channels. This three-layer structure biomimics the upper epidermis, palisade tissue/spongy layer, and lower epidermis of a leaf, forming an efficient directional liquid transport pathway (Fig. 1b) through a network of interconnected longitudinal and lateral pores. The lateral interconnecting network pores are developed into a helical nanofiber membrane (HNF membrane) with a three-dimensional interconnected network by utilizing the difference in elasticity between two polymers. Based on the fabrication principles of helical fibers mentioned above, we selected TPU and CA to prove the concept. It is worth noting that TPU and CA are not the only choices. Other materials satisfying the fabrication principles can be applied as well. With TPU exhibiting superior stretchability over CA, we employed a side-by-side electrospinning setup equipped with an off-centered core-shell spinneret to generate TPU/CA helical fibers (Fig. S1). The side-by-side structure was observed in a single helical fiber, as shown in Fig. S2. Upon solidification, TPU with more significant shrinkage imparted a helical nanofiber morphology, enhancing the membrane's porosity and horizontal interconnectivity (Fig. 1c). To refine the helical structure, hydrophilic PDA was introduced to modulate the TPU-CA interfacial dynamics. Subsequently, hydrophilic-underwater oleophobic PAN nanofibers and hydrophobic-underwater oleophilic TPU nanofibers were electrospun onto opposing surfaces of the HNF substrate, yielding the biomimetic PHT Janus fiber membrane. As exhibited in Fig. 1d, the cross-sectional SEM image of the three-layer fiber membrane shows that the three layers are tightly combined in the interfacial region with good physical bonding between the corresponding layers, each tailored for a specific function. The three-layer fiber structure (with the top and bottom surface structures shown in Fig. 1e) forms a pore gradient. The membrane efficiently pumps water from the hydrophobic layer to the hydrophilic layer by leveraging wettability and pore size gradients. The water is then continuously propelled upwards by wicking action. The photograph of the as-fabricated PHT membrane is displayed in Fig. 1f. Figure 1g, h shows good directional water transport properties by moisture management tester (MMT) tests that water is transported from the hydrophobic side to the hydrophilic side, while reverse osmosis is prevented. It is also verified with the visible stain in Fig. 1i that the magenta-stained water drop cannot be transported from the hydrophilic side to the hydrophilic side.
The molecular interactions between CA and TPU were further confirmed by density functional theory (DFT) (Fig. 2a and Fig. S4). Through comparing the different intramolecular interaction patterns between CA and TPU, as well as CA@PDA and TPU, it was found that the -OH groups in CA molecules form strong interfacial hydrogen bonds with the -C = O groups on TPU chains, with a bond length of 1.876 Å and binding energy of -0.405 eV. Before preparing HNF, PDA was premixed uniformly in CA solution for electrospinning, where the -OH groups in CA form stable intramolecular hydrogen bonds with the -C = O groups in PDA. Additionally, during the preparation of HNF, the -NH groups in PDA interact strongly with the -C = O groups in TPU, resulting in an interfacial hydrogen bond length of 1.796 Å and a binding energy further reduced to -0.537 eV, which is stronger than the bonding strength of CA and TPU. In this way, we do not necessarily consider the slippage between CA and PDA because they are surrounded by each other in the premixing. These results indicate that introducing PDA effectively enhances the interfacial hydrogen bonding interactions in the CA-TPU system and significantly improves the system's electrostatic potential stability. The molecular interactions among CA, PDA and TPU were further confirmed by molecular dynamic (MD) simulations (Fig. S5). Comparing the radial distribution functions (RDFs) of O atoms on CA chains next to the -NH groups in TPU (N-H---O) and the -OH groups in CA next to the O atoms in TPU (O-H---O), O-H---O RDF showed an obviously higher value at a shorter distance, confirming that the C = O bonds on TPU would preferably bond to the -OH groups on CA. In CA/PDA/TPU, the RDF of O-H---O on CA/PDA and N-H---O on PDA/TPU had higher values with shorter distance, indicating stronger bonding interactions. All these RDF results were consistent with the DFT results. The morphology and structural characteristics of HNF membranes are shown in Fig. 2b-d, showing the SEM images of HNF-X films with different PDA contents (0, 2, 4 wt.%) (Fig. S6a-f for SEM images with PDA contents of 0, 0.5, 1, 2, 3, 4 wt.%). The corresponding fiber diameter distribution is shown in Fig. S7a-f. HNF-0 membrane exhibits an irregularly coiled fiber morphology with an uneven distribution of fiber diameter (Fig. 2a and Fig. S7a). However, as PDA content increases, fibers evolve into a regular helical shape with uniform diameters, particularly evident in HNF-1 and HNF-2 membranes (Fig. S6c and Fig. 2b). This is mainly attributed to the ability of PDA to form adequate interfacial adhesion between CA and TPU, which enhances the interface bonding between the two in the side-by-side spinning process. However, excessive PDA (≥3wt.%) hampers fiber elongation and contraction, reducing helical fiber formation (Fig. S6e and Fig. 2c). Specifically, at 4 wt.% PDA, fibers predominantly display curved rather than regular helical structures. In summary, optimal PDA contents promote regular helical nanofiber formation by bolstering interfacial adhesion, whereas excessively low or high concentrations impede this structural development.
The reasons for the influence of PDA content on the helical structure of HNF-X membranes can be explained by comparing the formation of helical structure in side-by-side electrospinning process to the schematic diagram of double-layer prestressed rubber strip in concept, as shown in Fig. 2e. Here, the composite jet is envisioned as a composite strip comprising two intimately juxtaposed rubber-like layers of CA and TPU (Fig. 2e-i). The inherent material disparities between these polymers lead to differential deformations under electric field forces, resulting in varied longitudinal stresses and subsequent stretching (). The CA and TPU layers remain permanently bonded via interfacial hydrogen bonding, precluding interfacial mixing. Disregarding component intermixing during spinning, the interface between these rubber layers experiences shear stresses induced by electric field stretching, leading to spontaneous bending and an intrinsic curvature (K). Notably, the viscous resistance, akin to the stress level, necessitates the presence of hydrogen bonding between layers. Due to the high adhesion of catechol and amino functional groups, the active groups of PDA in the modified HNF-X membrane system increase the formation of hydrogen bonds. In the HNF-X membrane system, the stretching of the composite jet within the electric field harnesses the PDA's bridge effect to amplify viscous resistance at the interface. This reinforcement fosters tighter integration between the CA and TPU layers, enhancing their longitudinal deformation (, Fig. 2e-ii), a pivotal factor in efficiently producing two-component helical fibers. However, excessive PDA content paradoxically diminishes the deformation disparity () between the layers by strengthening their bond, thereby reducing shear stresses essential for bending and helical structure formation (Fig. 2e (iii)).
In addition, the helical structure of HNF-X fibers prepared with different PDA contents was analyzed. Figure 2f shows spiral curvature (K) and pitch (H) measurements as a function of PDA concentration. As PDA concentration increases, K initially rises and declines, while H exhibits an inverse trend. This aligns with SEM findings, indicating that HNF-2, prepared with 2 wt.% PDA, possesses the most compact helical structure, with a minimum H of 1.1 μm and maximum K of 1.3. Notably, the helical fiber structure directly influences the pore size and porosity of the membranes. As depicted in Fig. S8-S9, an increase in helical curvature coincides with a decrease in pore diameter and a rise in porosity, specifically at 2 wt.% PDA, HNF-2 achieves a K of 1.3 and a peak porosity of 87.5%. Furthermore, adjusting PDA content effectively turns the membrane's average pore size, initially expanding and then contracting from 62.7 μm (HNF-0) to a minimum of 48.1 μm (HNF-2), after expanding again to 65.4 μm (HNF-4). Thus, precise modulation of fiber helical structure through PDA content offers a viable strategy for tailoring three-dimensional network pore channels in HNF membranes, significantly impacting their pore size and porosity.
After electrospinning, the microstructural properties of the HNFs were thoroughly investigated using XRD and FTIR analyses. The XRD patterns (Fig. S10) reveal that HNF-0 exhibits two broad peaks at 2θ = 9.0° and 19.1°, attributed to the 101 crystallographic plane of CA and the hard segment crystal peak of TPU. Notably, the inclusion of PDA nanoparticles in HNF-X membranes did not disrupt the crystallization process of the CA-TPU nanofiber composites, as evidenced by the preservation of these peaks within the same 2θ range. Instead, PDA acted primarily as an interfacial adhesion enhancer.
The FTIR analysis (Fig. 2g) of HNF-0 reveals characteristic absorption bands at 3400, 1725, 1610, and 1250 cm, associated with the stretching vibrations of -NH, C = O in TPU and -C = O, -O- in CA, respectively. With PDA addition, the absorption peaks at the 3700-3500 cm region became sharper and denser, indicating an increase in free hydroxyl groups likely due to PDA's hydroxyl groups and its promotion of hydrogen bonding network rearrangement (Fig. S11). Additionally, the presence of PDA is confirmed by the intensifying absorption within 2360 cm and 2340 cm characteristic of its benzene ring. Notably, the absorption bands at 3400 cm and 1610 cm diminish in PDA-modified HNF-X, attributed to PDA's high surface adhesion and reactivity, which facilitate interfacial bonding between CA and TPU via hydrogen bonding formation between PDA's catechol and amino groups with CA's ester and TPU's amino groups, respectively. This interfacial strengthening plays a pivotal role in shaping helical fibers. Furthermore, PDA significantly improves the wettability of the fiber membranes (Fig. 2h) and increasing PDA content leads to a progressive decrease in contact angle mainly due to the abundant hydroxyl and amino functional groups in PDA molecules. These functional groups formed many hydrogen bonds on the surface of HNF-X membranes, which significantly improved the wettability of HNF-X membranes, indicating that PDA enhanced the hydrophilicity of HNF-X membranes.
We conducted water permeation tests to assess the improvement in water transport efficiency of the PHT membrane. Figure 3a is a panoramic view of a three-layer fiber membrane constructed by layer-by-layer deposition. Figure 3b illustrates the water transport pathway within the PHT membrane. The membrane efficiently pumps water from the hydrophobic to the hydrophilic layer by leveraging wettability and pore size gradients. Notably, including the HFN membrane as a buffer absorption layer facilitates the absorption and infiltration of water into its horizontally interconnected pores, overcoming gravity resistance that straight nanofiber longitudinal channels might encounter. Utilizing dynamic water contact angle (WCA) analysis, we evaluated the wettability of various membranes, including TPU, PAN, and PHT membranes with varied PDA-modified buffer layers (Fig. 3c). Notably, the PAN membrane rapidly absorbed a water droplet, reducing WCA from 60.5° to 0° in 2.3 s. Conversely, HNF-X membranes exhibited accelerated absorption rates with increasing PDA content, with spreading times ranging from 12.5 to 3.4 s, though still slower than PAN. The TPU membrane remained hydrophobic, maintaining a WCA of 132°. These findings confirm the successful fabrication of PHT-X Janus fiber membranes featuring gradient wettability and pore structures (Fisg. S7, S8, and Fig. S12). Further analysis of the DLT performance, focusing on the influence of helical structure on the HNF-X intermediate layer, revealed enhanced reverse hydrostatic pressure (PAN to TPU) and reduced forward pressure (TPU to PAN) compared to bilayer PAN/TPU membranes (Fig. 3d). Additionally, with the increase of the regularity of spiral structure in PHT-X Janus membranes, the positive static pressure decreases. The reverse static pressure of PHT-X Janus fiber membranes increases with increased hydrophilicity of HNF-X fiber membranes. Remarkably, incorporating the HNF-2 membrane as a central buffer layer facilitated effortless water passage forward, requiring a minimal hydrostatic pressure of 6.5 cm HO (0.6 kPa). This underscores the pivotal role of horizontally interconnected cellular networks formed by regular helical structures in enhancing water transport. Conversely, water flow in the reverse direction encountered significant resistance, necessitating a hydrostatic pressure of at least 23.1 cm HO (2.0 kPa), attributed to the hydrophilic layer's smaller pores and hydrophilic nature, effectively barricading water passage.
Furthermore, utilizing a moisture management tester, we quantified the DLT capacity of PAN/TPU bilayer and PHT-X Janus fiber membranes. The droplet transport performance of the hydrophobic side of PHT-X fiber membranes is shown in Fig. S13a-g. The superior DLT performance of PHT-X Janus membranes was tunable by modulating the helical structure regularity in the buffer layer. Notably, the unidirectional liquid transfer R-values reached 806% to 1250%, peaking at 1250% with optimal structure. As is shown in Fig. 3e, when HNF-2 served as the buffer layer, water content on both sides surged initially (0-20 s) upon droplet contact with the hydrophobic surface. Swiftly, the middle layer drew water to the adjacent hydrophilic layer, fueled by the wetting and pore gradients' pumping force. Simultaneously, the PAN membrane's capillary force accelerated surface water diffusion. This synergy yielded a DLT with an R-value 2.4 times that of the bilayer PAN/TPU (514%), spanning 20-120 s. This behavior is also confirmed by the water distribution images of the top hydrophobic and bottom hydrophilic surfaces (Fig. 3f) during the moisture management test, with blue and white tones indicating wet and dry areas, respectively. Therefore, we can conclude that the helical structure can help with DLT properties by comparing the PAN/TPU bilayer and PHT membranes. Better DLT capacities can be achieved with a more regular helical structure.
At the same time, we tested the transport performance of water droplets from the hydrophilic side of the PHT-X fiber membranes and compared the DLT and anti-reverse osmosis properties, as shown in Fig. S14a-g. In the MMT results of the PAN/TPU fiber membrane, some water droplets permeate from the top hydrophilic layer to the bottom hydrophobic layer, and the R is -975%. In contrast, Fig. S14b-g shows the osmosis properties of PHT-X fiber membranes at different HNF-X levels. As the helical structure of the HNF-X fiber membrane gradually decreases and its hydrophilicity increases, the anti-reverse osmosis properties of PHT-X fiber membranes are significantly improved. The water content of the hydrophobic side on the bottom surface is gradually close to zero. R increased from -1050 to -1912%. This indicates that the structural optimization and good hydrophilicity of the HNF-X layer significantly enhance the anti-osmosis ability of the PHT-X fiber film, ensuring that water droplets only travel in a single direction.
In practical scenarios, liquids are efficiently extracted from the skin-facing hydrophobic TPU layer of the PHT-2, traversing the buffer layer to the outer hydrophilic PAN layer, where they finally evaporate. To simplify comprehension of this directional transport, we have constructed a visual model (Fig. 4a, Supplementary Movie 1). Upon contact with the magenta-dyed hydrophobic surface, the droplet is promptly drawn through the buffer layer and dispersed into the PAN layer, completing the transfer within 3 seconds. Conversely, a droplet on the hydrophilic side rapidly spreads within this layer, forming a larger droplet circle, yet fails to penetrate the hydrophobic layer (Fig. 4b, Supplementary Movie 2). We conducted antigravity-driven experiments to verify the continuous, directional water transport prowess of PHT-X Janus fiber membranes (Fig. 4c, Supplementary Movie 3). The antigravity phenomenon unfolded in five stages: contact, pumping, transport, spreading and evaporation. With the hydrophobic TPU layer facing downwards, droplets ascended to make contact. Upon touching the TPU layer, water was swiftly pumped into the buffer layer. This rapid transfer stems from the interplay between the wetting gradient and porosity structure disparities between layers, generating a driving force (F) and capillary pressure difference (∆P) that efficiently channels water into the inter-fiber capillary channels of the buffer layer. The wetting driving force and are represented by Eqs. (1) and (2),
In Eq. (1) is the surface tension between the liquid and the material surface, is the contact angle of the liquid at the position, is the contact angle of the liquid when it is far away from any surface, and the integration region [A, B] represents the change of the liquid's position between the hydrophobic layer and the buffer layer. In Eq. (2), and are the Laplace pressures of the hydrophobic and buffer absorbing layers, respectively, γ denotes the interfacial tension between the liquid and gas phases, and are the WCAs of the hydrophobic and buffer absorbing layers, respectively, as well as and refer to their respective capillary channel diameters. Notably, the capillary pressure difference () between the two layers and the capillary force in the buffer absorbing layer () enable water to overcome the hydrophobic viscous resistance () and conduct upward from the hydrophobic side to the transport layer under low water velocity and low G conditions. The capillary force in the buffer absorbing layer and the hydrophobic viscous resistance can be expressed by Eqs. (3) and (4), respectively:
The in Eq. (7) represents the diameter of the three-phase contact line in the buffer absorbing layer and the capillary force is derived from the Laplace pressure , which is opposite to the pore radius. The in Eq. (8) is the diameter of the three-phase contact line in the hydrophobic layer. is the conical conicity formed by the difference in pore size between the hydrophobic layer and the buffer absorbing layer. The capillary force () generated by the horizontal interconnected network channels in the buffer absorbing layer promotes the diffusion of water within the buffer layer, reducing the gravitational load on the upward transport of water. Additionally, the capillary pressure difference in the PHT-X Janus fiber membrane, where is greater than , further enhances the continuous upward pumping of water. Similarly, the interfacial Laplace pressure difference () between the buffer absorbing layer and the hydrophilic PAN layer (, where is the Laplace pressure of the hydrophilic layer) is similarly oriented upward to continue the extraction of water from the buffer absorbing layer to the hydrophilic PAN layer. Once the water contacts the hydrophilic PAN layer, the main driving force immediately tunes into a capillary force (, where is the diameter of the three-phase contact line in the hydrophilic layer, and is the WCA of the hydrophilic layer), which induces the droplets to rapidly diffuse and evaporate on its surface. This mechanism is consistent with the prediction of Murray's law that a multiscale network of pore interconnections in a porous medium maximizes the transport rate of a finite liquid and minimizes the transport resistance. As a result, the combined force applied vertically to the liquid always remains upward, resulting in unidirectional and irreversible transport of the liquid as it moves. These results indicate that the three-layer fabric with gradient wettability and pore structure effectively facilitates the directional transport of the liquid. The horizontally interconnected network channels in the intermediate layer serve as a buffer absorbing layer and reduce gravitational resistance, thereby aiding in the anti-gravity transport of the liquid.
We demonstrate its potential for oil-water mixture treatment to bridge the gap between PHT membrane and practical use. Wettability is crucial for successful oil-water separation by fiber membranes. Figure 5a reveals that PHT-X Janus membranes exhibit asymmetric wettability: the hydrophilic side is oleophobic (oil contact angles ranging from 113.3° to 133.3°). In contrast, the hydrophobic side is super-oleophilic (5.7° oil contact angle). In addition, the pre-wetted PHT-X Janus fiber membranes exhibit unique wetting behavior on both sides of the oil (take the PHT-2 Janus fiber film as an example). When a pre-wetted PHT-2 Janus membrane's hydrophilic side encounters an acidic magenta-stained water droplet in oil, it swiftly absorbs the water (Fig. 5b, Supplementary Movie 4). Conversely, the pre-wetted hydrophobic side exhibits remarkable oil absorption and water rejection, even when submerged in oil (Fig. 5c, Supplementary Movie 5). These findings underscore the potential of PHT-X Janus membranes' unique wettability for diverse oil-water separation applications. This asymmetry enables efficient separation, as evidenced by the membrane's ability to block 50 g of Sudan III-stained hexane while allowing 50 mL of methylene blue-stained water to pass through rapidly (Fig. 5d, Supplementary Movie 6). Figure 5e shows separation efficiencies exceed 98% with fluxes up to 13227 L·m·h, peaking at 98.92 ± 0.18% and 13,860.77 ± 330.04 L m h for PHT-2. Notably, when dry PHT-X membranes with the hydrophobic side up encounter an n-hexane-water mixture, oil flow is initially hindered by viscosity but eventually permeates, highlighting the membrane's versatility under varying conditions. This indicates that the membrane cannot block the oil in its dry state. In addition, the PHT-2 Janus fiber membrane showed good separation stability (Fig. 5f). After 10 separations, the separation efficiency remained above 98%, and the separation flux was as high as 13231 L m h, indicating excellent reusability.
Based on the DLT mechanism, the PHT-X Janus fiber membrane performs excellently in oil/water mixture separation. Due to the DLT characteristics of water, water first contacts the PHT-X Janus fiber membranes and quickly passes through, forming a water film on the surface of the membrane to block the passage of oil and achieve oil/water separation. Compared to previously reported fabric/fiber membranes (Fig. 5g, Table. S1), PHT-2 Janus fiber membranes demonstrate a better separation performance with even higher separation throughput at the similar high separation efficiency. This work provides a sustainable and efficient industrial wastewater treatment and Marine oil cleanup solution.
As shown in Fig. S15, with the addition of the PHT spongy layer, the maximum stresses of the membranes were improved at least 2.5 times, and the breakage strains were increased by 4 times, compared with PAN/TPU. Besides, it is notable that the membranes with the buffer layer have a steady plateau stress, especially for the PTH-2 membrane, which is caused by the helical fibers to increase their stretchability, and it is vital for human wearables. Therefore, we conclude that the PHT-2 Janus fiber membrane exhibits better mechanical properties, demonstrating its potential for human sweat conditioning and heat management garments. We integrated the high-performing PHT-2 Janus fiber membrane with various conventional fabrics (KF, WF, and DLT-KF). This integration aimed to enhance moisture management efficiency and reduce body surface temperature. By incorporating a wettability gradient, we aimed to facilitate automatic sweat evacuation from the skin to the environment, fostering a dry and comfortable microclimate in hot, humid settings. As depicted in Fig. 6a, b, we designed an advanced moisture-wicking and cooling garment utilizing the PHT-2 composite fabric. To assess the moisture management capabilities of these composites, we employed the moisture management tester method, utilizing the unidirectional transfer index (R-value) as a metric for moisture conductivity. The results in Fig. 6c reveal that the exceptional DLT properties of the PHT-2 membrane significantly boosted the moisture management performance of all tested fabrics. Notably, the R-values of the original fabrics KF, WF, and DLT-KF improved dramatically upon lamination with PHT-2. Specifically, KF/PHT-2, WF/PHT-2, and DLT-KF/PHT-2 achieved R-value enhancements of 13 times, 8 times, and 1 time, respectively. This remarkable improvement stems from the optimized pore structure and hydrophilicity gradient imparted by the PHT-2 membrane, ultimately enhancing the overall liquid management capabilities of the textile. Fig. 6d shows the general enhancement effect of PHT-2 fiber membrane on the moisture management capability of various fabrics. By combining PHT-2 with KF of different materials and structures, the moisture permeability of the composite samples was evaluated by the inverted cup method. Results showed that the DLT properties of PHT-2 fiber membrane help improve the humidity management capability of these fabrics, especially for KF5, with a 59.2% increase. In addition, the breathability of the composite sample was also tested, and the results are shown in Fig. 6e. The breathability range of the composite sample is 34.56-91.74 mm/s, which shows not only good air mobility but also has specific wind resistance, showing its broad potential in a variety of applications.
Beyond moisture management, thermal regulation is vital for textiles in real-world use. We evaluated thermal properties by measuring fabric surface temperatures at 100 seconds via infrared thermography. As Fig. 6f demonstrates, fabrics laminated with the PHT-2 Janus membrane exhibit lower temperatures than their unlaminated counterparts, confirming their ability to provide a cooling effect in hot environments. KF/PHT-2, WF/PHT-2, and DLT-KF/PHT-2 cover reduced fabric surface temperatures by 2.5 °C, 2.9 °C, and 3.3 °C, respectively, compared to their base fabrics. This cooling effect stems from the membrane's efficient liquid transport, facilitating sweat evaporation and heat dissipation, lowering fabrics' surface temperatures. Thus, the PHT-2 Janus membrane boosts the fabric's unidirectional liquid transport and realizes effective personal thermal management. Compared to previously reported fabrics and fiber membranes with thermal regulation (Fig. 6g, Table. S2), fabrics with PHT-2 films combined demonstrated superior cooling effects. Moreover, the PHT film had good lamination strength with fabrics demonstrated by the wear abrasion and laundry experiments (Figs. S16-S17). This research provides a new direction for developing functional garments suitable for high temperature and high humidity environments and has significant application value.