【作者】 李明；

【导师】 赵爱武；

【作者基本信息】 中国科学技术大学 ， 无机化学， 2011， 硕士

【摘要】 壁虎能够在墙壁、天花板等任何表面做无障碍运动,其高超的攀爬能力一直是近年来科研人员重点研究对象。壁虎具备超强的粘附能力是因为其脚掌上长有无数根由超疏水性的β-角蛋白构成的超细刚毛阵列。这种粘附力来自绒毛与接触表面的范德华力。制造仿壁虎脚掌刚毛阵列需要考虑阵列的尺寸、形貌、弹性模量以及倾斜角等因素。通过仿制这种具有超细绒毛结构的材料可以实现极高的实用价值。贻贝等软体动物中有一种特殊的粘附蛋白,可在水下与固体表面形成交联,用以粘附并固定在外界的各种固体表面。贻贝中的这种粘附蛋白都含有多巴胺(DOPA),含有多巴的天然或合成粘附剂都具有很强的粘附力,而且多巴含量越高粘附力越大。多巴胺修饰的微阵列在潮湿环境下仍然具有粘附作用的特点。这样,经过多巴胺修饰过的粘附阵列具有更广泛的应用。论文第一章回顾了仿生壁虎脚掌的研究进展,概况了壁虎的粘附、脱附机理。另外还介绍了利用不同手段和不同材料制备的微纳粘附阵列。最后简单地介绍了粘附阵列的力学测试方法。论文第二章主要介绍了微米级和纳米级粘附阵列的制备工艺并设计实验平台测试宏观粘附力。用原子力显微镜测试微观粘附力。合成了仿贻贝粘附蛋白聚合物-多巴胺-甲基丙烯酸酰胺/甲氧基乙基丙烯酸酯共聚物(P(DMA-co-MEA)),然后修饰在聚氨酯粘附阵列上。实验发现多巴胺修饰后的样品粘附力大大提升,而且在水中也有很好的粘附效果。最后探讨了修饰机理以及粘附机理。在第三章中,选择以4,4`-二苯基甲烷二异氰酸酯(MDI)为单体制备聚氨酯高分子材料,通过调整单体MDI和聚四氢呋喃(PTMG)以及1,4-丁二醇的比例可以调整软硬段的比例从而实现弹性模量的改变。用聚二甲基硅氧烷(PDMS)模板可以得到不同尺寸的聚氨酯粘附阵列。通过纳米压痕仪器测试高分子材料的弹性模量和粘附阵列的粘附力大小,实验结果发现:聚氨酯中软段比例提高可使弹性模量变小;弹性模量调节的范围介于0.62~175MPa;聚氨酯阵列的直径尺寸变小可使阵列的有效弹性模量变小;随着粘附阵列弹性模量的减少,粘附阵列的粘附力大小随之增大。这些实验结果都和理论计算值相吻合。更多还原

【Abstract】 Geckos can walk freely on the walls, ceilings and any other surfaces, which attracted the focus of the researchers in recent years. The climbing ability of geckos is attributed to fibrillar arrays, consisting of stiff, hydrophobicβ-keratin which covers the bottom of gecko’s feet. Such high dry adhesion between the feet and surfaces originates from Vander Waals forces. To mimic gecko foot hairs, surface design parameters such as pillar size, shape, elastic modulus, or tilt angle need to be considered. To simulate the materials with microstructure has a high practical value. Mussels have a special adhesion to surface in the water. The amazing ability of adhesion is due to a kind of proteins in mussels that is dopamine (DOPA). Either natural or synthetic DOPA has an excellent adhesion. The higher content of the DOPA has a greater adhesion. Dopamine-modified microarrays have an ability of adhesion in a wet environment. It can broaden the application of the microarrays by the modification of dopamine-polymer.In the first chapter, we reviewed the development of bio-mimick gecko and generalize the mechanism of the adhesion and detachment. In addition, we introduced the preparation of the gecko-inspired arrays by different methods and different materials. In the last, we introduced the main methods of the adhesion measurement.In the second chapter, we introduced the fabrication technology of the micro/nano polymer arrays and designed a platform to investigate the macro adhesion of the fabricated arrays. Atomic force microscope(AFM) was utilized to measure the micro adhesion of the arrays. 3,4-dihydroxy-ι-phenylalanine(DOPA) was synthesized and then was modified to the polyurethane polymer arrays. The experimental result shows that the dopamine-modified microarrays can enhance the adhesion of the, also have an ability of adhesion in a wet environment. We have also discussed the mechanism of the modification and adhesion of the arrays.In the last chapter, segmented polyurethane (PU) was utilized to fabricate micro arrays by the porous polydimethyl siloxane (PDMS) membrane molding method. We fabricated a series of segmented PU from 4, 4’- diphenylmethane diisocyanate (MDI), Polyoxytertramethylene Glycol (PTMG) (Mn = 1000), with 1, 4– butanediol (BDO) as the chain extender. We studied the influence of the elastic modulus on the gecko-inspired dry adhesion by regulating the elastic modulus of bulk polyurethane combined with changing the size of microarrays. By varying the ratios of hard and soft segments of the bulk PU and changing the radius of the PU arrays, regulation of the elastic modulus of PU micro arrays is achieved to realize the modulation of the dry adhesion. The properties of the micro arrays, such as the elastic modulus and adhesion were investigated by Triboindenter. The study demonstrates that bulk surfaces show the highest effective modulus, with similar values at around 175 MPa and decreasing the arrays radius causes a significant decrease in E, down to 0.62 MPa. The corresponding adhesion experiment shows that decrease of the elastic modulus can enhance the adhesion which is consistent with the recent theoretical models.更多还原