纤维对液体气溶胶阻拒机制及其结构设计理论研究

As the aggravation of environmental pollution and the occurrence of local terrorism, people are faced with challenges of some liquid aerosols that can cause health problems and even endanger human life. Conventional superhydrophobic/superoleophobic materials are incapable of resisting liquid aerosols mainly because liquid aerosols tend to condense into liquid film on material surface rather than liquid drops. However, the formation of liquid film makes it difficult to separate liquids from materials. To protect people from the threat of liquid aerosol explosives, it is proposed in this project to investigate：the effect of fiber parameters on the forms of micro liquid resulting from liquid aerosols on a single fiber and multi fibers standing on the material surface, the effect of fiber parameters on the mobility of micro liquid resulting from liquid aerosols on a single fiber and multi fibers, and the effect of fiber parameters on the formation of easily-roll-off liquid drops on textile surface. A model is built to describe the condensation of liquid aerosols on a single fiber and multi fibers, and elucidate the relationship between fiber parameters and the mobility of micro liquid resulting from liquid aerosols. Experiments are designed and carried out to investigate the effects of the top end structures and bending properties of fibers on the transfer of micro liquid onto textile surface. The mechanism for the textile fiber materials resisting liquid aerosols is proposed, from which the design principle of material structures is drawn to guide the preparation of textile fiber materials for resistance of liquid aerosols.

随着环境污染的加剧及局部恐怖主义的实施，人类面临对人体健康甚至生命有危害的液体气溶胶的挑战。普通超疏水/超疏油材料对液体气溶胶缺乏阻拒能力。这主要是因为气溶胶的液体性质导致其在材料表面聚集后形成液膜而不是较大液珠。液膜的形成使液体和材料的分离变得困难。为了解决由微小体积的液体气溶胶导致的材料被润湿问题，本项目拟通过研究各纤维参数对液体气溶胶微液在直立于基材上的单根纤维及纤维丛上的聚集形态及发生定向移动性能的影响、各纤维参数对微液在纤维顶端表面形成易脱离大液珠的影响，建立液体气溶胶微液在纤维及纤维丛上的聚集模型，明确各纤维参数与微液移动性能的关系，阐述纤维顶端微结构及弯曲弹性对微液由纤维转移到材料表面形成易脱离液珠的影响；获得纤维对液体气溶胶的阻拒机制，提出相关材料结构设计理论，制备出对液体气溶胶具有阻拒功能的纤维基材料。

液体气溶胶(直径0.001～100μm)在特定情况下会对材料、人体健康甚至生命构成威胁。常见疏水/疏油材料主要用于阻拒体积较大的液体（直径大于1mm），对具有微小体积的液体气溶胶缺乏阻拒作用。这是因为液体气溶胶的液体特性决定了其聚集后易于在材料表面形成润湿性液膜而不是易脱离的液珠，即材料被液体润湿。本项目由液体气溶胶的物理特性及材料表面物理化学结构入手，通过对Lady's Mantle叶片在潮湿、多雾的条件下能排斥微滴聚集液特性的研究，探讨液体气溶胶微液在单根纤维及纤维丛上的聚集模型及其定向移动机制和液体气溶胶微液在纤维丛顶端表面形成易于脱离大液珠的机制，获取纤维对液体气溶胶的阻拒机制，为可阻拒液体气溶胶材料领域的研究做出贡献。研究发现，Lady's Mantle叶片底材为蜡质突起且叶片覆盖绒毛。突起表面含有纳米级褶皱，绒毛尖处存在曲率结构突变，绒毛表面有棘轮修饰。这种物理结构使得微小液滴更容易在绒毛的上端形成液滴。随着液滴沉降，绒毛上液滴尺寸变大，相邻绒毛上的液滴接触后汇集成较大液滴。由于绒毛限制，液滴发生形变，导致液滴上部和下部存在拉普拉斯压力差，其可驱动液滴沿绒毛向上运动，并达到绒毛顶端。绒毛顶端液珠随着体积增大而相互接触，因汇集而产生内能，其驱动液珠按绒毛倾斜方向移动，从而脱离叶片表面。由Lady's Mantle叶片阻拒微小液滴润湿机理可知，叶片表面绒毛及基底突起、绒毛几何结构及分布、绒毛上的棘轮及分布是决定影响因素。课题组利用静电植绒、纳米硅球沉积及低表面能处理模拟了Lady's Mantle叶片微结构，成功制备了可阻拒液体气溶胶等微小体积液体的仿生功能材料。通过控制处理电压、绒毛大小、密度和后处理工艺可以获得具有不同级别阻拒能力的功能材料。该工艺操作简单，不仅可应用于纺织领域，还可推广至化工、建材、厨房等领域。