NIR驱动MWCNT修饰的超滑PI光热响应膜表面液滴定向输运

NIR-Induced Directional Droplet Transport on MWCNT-modified Ultra-slippery PI Photothermal Responsive Membrane Surface

目的制备多壁碳纳米管(MWCNT)修饰的超滑聚酰亚胺(PI)光热响应膜表面,实现近红外光(NIR)驱动液滴定向输运。方法基于静电纺丝结合喷涂法制备MWCNT修饰的超滑PI光热响应膜表面,分别通过扫描电子显微镜、接触角测量仪、红外热成像仪表征样品的微观形貌、润湿特性及光热特性,分析液滴大小与润滑油黏度对液滴定向输运的影响规律,研究NIR驱动液滴在MWCNT修饰的超滑PI光热响应膜表面定向输运的作用机理。结果 MWCNT修饰PI膜表面的疏水性提高,液滴静态接触角从115°增大至160°。NIR连续照射MWCNT修饰的超滑PI光热响应膜表面90 s,表面温度的最大上升速率为42.6℃/s,表面最大温度达到123.6℃。通过NIR照射超滑PI纳米纤维膜表面,表面局部温度上升,产生润湿梯度力,驱动液滴在表面定向输运。液滴定向输运与润湿梯度力及粘滞阻力有关。超滑PI光热响应膜表面的润滑油黏度相同时,液滴体积越小,粘滞阻力越小,液滴定向输运的速度越快。5mL液滴在润滑油黏度为0.65 mm^(2)/s的超滑PI光热响应膜表面的运动速度最大,运动速度为1.64mm/s。液滴体积相同时,超滑PI光热响应膜表面的润滑油黏度越大,液滴受到的润湿梯度力越小。5mL液滴在润滑油黏度为100 mm^(2)/s的超滑PI光热响应膜表面的润湿梯度力F_(wet-grad)最小,润湿梯度力为6.39×10^(-6)N。结论 MWCNT修饰的超滑PI光热响应膜表面具有良好的光热效应,NIR可精准驱动单液滴及多液滴在表面的定向输运。

This work aims to design ultra-slippery polyimide(PI)photothermal responsive membrane surface modified by the multi-walled carbon nanotube(MWCNT)and to achieve directional droplet transport under near-infrared(NIR)irradiation stimuli.The surface morphology,wettability and photothermal property of the sample characterized by scanning electron microscope(SEM),optical fiber goniometer and infrared thermal imager respectively,in combination of the MWCNT-modified ultra-slippery PI photothermal responsive membrane surface,fabricated through the combined electrostatic spinning technique and spray method,were used to investigate the influence of droplet volume and lubricant viscosity on the directional droplet transport and to study the mechanism of directional droplet transport under near-infrared(NIR)irradiation stimuli.The results indicated that the surface hydrophobicity of PI membrane was improved after being modified by MWCNT and the droplet static contact angle has increased from 115°to 160°.When the MWCNT modified slippery photothermal responsive PI membrane surface was exposed 90 s under NIR,the maximum surface temperature rising rate reached 42.6℃/s and the maximum surface temperature was up to 123.6℃.After the irradiation of NIR,the local temperature of MWCNT-modified ultra-slippery PI photothermal responsive surface rised,and wetting gradient force was formed on its surface,which drived droplets to transport directionally.Directional droplet transport was influenced by wetting gradient force and viscous resistance.With the same lubricant viscosity on the MWCNT-modified ultra-slippery PI photothermal responsive surface,the velocity of droplet transport increased with the decreasing of droplet volume and hydrodynamic resistance.For a water droplet(5mL)on the MWCNT-modified ultra-slippery PI photothermal responsive membrane surface(lubricant viscosity:0.65 mm2/s),the highest droplet velocity was 1.64 mm/s.With the same droplet volume,the wettability gradient force decreased with the increasing of lubricant viscosity.For a water droplet(5mL)on the MWCNT-modified ultra-slippery PI photothermal responsive membrane surface(lubricant viscosity:100 mm2/s),the smallest wettability gradient force was 6.39×10^(-6) N.The experimental results shows that the MWCNT-modified ultra-slippery PI photothermal responsive membrane surface has good photothermal property and single-droplet and multiple-droplet both can be precisely manipulated on the MWCNT-modified ultra-slippery PI photothermal responsive membrane surface under NIR stimuli.