改性PU海绵三维多孔界面蒸发器的制备及性能

采用聚乙烯醇(PVA)对商用疏水聚氨酯海绵(简称PU海绵)进行亲水改性，并在其上面喷涂多壁碳纳米管/聚二甲基硅氧烷(MWCNTs/PDMS)复合分散液，获得一侧超疏水另一侧亲水的三维多孔界面蒸发器。采用SEM、红外热像仪及紫外-可见-近红外分光光度计对涂层表面形貌、光热响应能力及反射率和透过率进行了测试，并对构建的三维多孔界面蒸发器的性能进行了评价。结果表明，由MWCNTs含量(以PDMS预聚物质量分数为0.55%的四氢呋喃溶液的质量计，下同)为0.5%的MWCNTs/PDMS复合分散液喷涂亲水改性的PU海绵制得的三维多孔界面蒸发器表面温度为81℃，吸收率为98.57%，具有良好的透水汽性、光热性能、蒸发性能、拒盐性能、脱盐性能、自清洁性能。该三维多孔界面蒸发器在盐水中进行蒸发作用时，其在1个太阳光强(1.0 kW/m²)下的表面温度为61.3℃，光热转换效率达96.75%，在模拟海水(质量分数为3.5%的NaCl溶液)蒸发过程中，蒸发速率可达1.80 kg/(m²·h)，而PU海绵的蒸发速率较低，仅为0.44 kg/(m²

Preparation and performance of interfacial evaporator of modified polyurethane sponge with 3D porous structures

3D porous interfacial carbon materials have high-efficiency in water evaporation at the solution interface, which have important application prospects in the field of outdoor solar driven seawater desalination. Polyvinylalcohol (PVA) was used to modify polyurethane sponge with hydrophilicity, and multi-wall carbon nanotubes / polydimethylsiloxane (CNTs/PDMS) composite dispersion was sprayed on the front of the PVA modified sponge to obtain a 3D porous Janus solar driven interfacial evaporator with the front side super-hydrophobic and the backside hydrophilic. The wide band high solar absorptivity (> 95%) and the photothermal conversion effect of CNTs endow the sponge with interfacial water evaporation capability. The rough structure of the CNTs and the low surface energy property of the PDMS endow the photothermal absorption layer with superhydrophobicity. Thus, the modified polyurethane sponge can not only float on the water surface, but also have self-cleaning and salt blocking effects. Hydrophilicity of the PVA helps the modified polyurethane sponge form excellent water transport channels. The test results show that the evaporation rate of the modified polyurethane sponge with 3D porous structures as an interfacial evaporator can reach 1.80 kg m-2 h-1 under one solar intensity (1 kW m-2) for evaporation of simulated seawater (3.5 wt% salinity).