阵列凹坑结构分布与水滴黏附性质的关系  

Effects of Distribution of Microconcave Array with Nanofolds on the Water Adhesive Property of PDMS Films

作　　者：王景明[1] 王春[1] 王明超[1] 江雷[1,2] 

机构地区：[1]北京航空航天大学化学与环境学院,北京100191 [2]中国科学院化学研究所,分子科学国家实验室,北京100190

出　　处：《高等学校化学学报》2012年第10期2333-2338,共6页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:20901006);中央高校基本业务科研费专项资金(批准号:YWF-10-01-B16)资助

摘　　要：以新鲜玫瑰花花瓣正面为模板,采用模板印刷法制备具有微米级阵列凹坑和纳米级沟壑结构的聚二甲基硅氧烷(PDMS)薄膜,通过对该薄膜逐级拉伸改变其微观结构的分布;采用场发射扫描电子显微镜(SEM)和原子力显微镜(AFM)观察了不同拉伸程度下薄膜表面微观结构的变化,采用高敏感性微电力学天平测试了样品表面微观结构变化过程中水滴的黏附力,分析了其微观结构分布与水滴黏附性质的关系;采用接触角测量仪表征不同拉伸条件下薄膜的浸润性.结果表明,随着PDMS薄膜被逐次拉伸,单位面积内的凹坑结构数目减少,且凹坑逐渐分离,凹坑的深度逐渐降低,水滴更容易浸入到凹坑结构中,因此水滴与薄膜的黏附力急剧增大;随着薄膜进一步拉伸,纳米级沟壑结构会随着凹坑的拉伸而不断伸展,纳米级沟壑结构的面积增加,纳米沟壑结构诱捕的空气量逐渐上升,导致水滴与薄膜表面的接触面积降低,使得水滴与薄膜的黏附力下降;继续拉伸PDMS薄膜,纳米级沟壑结构进一步伸展,水滴逐渐浸入纳米级沟壑结构中,水滴与薄膜的黏附力缓慢增大,当水滴完全进入到纳米级沟壑中时,水滴与薄膜的黏附力达到极大值,此时继续拉伸PDMS薄膜,纳米级沟壑结构随着拉伸程度的增加继续伸展,水滴与薄膜的接触面积稍有减少,黏附力将有所下降,直至薄膜被完全破坏.由此可见,微米级凹坑结构和纳米级褶皱结构的分布是影响PDMS薄膜对水滴黏附性质的主要因素.PDMS films with microscaled concave array and nanofolds were prepared by a cas-ting technique u- sing the front rose petal surfaces as the template. The distribution of the PDMS film＇ s microstructures was changed by stretching the film all-directionally. The morphology of the PDMS films was observed by field emis- sion scanning electron microscope （SEM） and atomic force microscope （AFM） at different stretch stages. The water adhesive effect was characterized by the high-sensitivity microelectromechanical balance system, and the effect of micro- and nano-structure on the water adhesive property of the PDMS film was investigated by alte- ring the stretch stage. The wettability was characterized by the apparent contact angle. The experimental re- sults show that the distribution density and the depth of the microconcave decreased through stretching, and the adjacent microconcaves separated from each other gradually. The water droplet could immerse into the mi- croconcaves much more easily, and the adhesive force between the water droplet and the film increased imme- diately. Besides, the nanofolds in the bottom of the microcaves would be stretched with the stretch of the film. With the stretch of the nanofolds, more air could be trapped and the adhesive force would decrease. If the water droplet could immerse into the nanofolds, the adhesive force would increase again. After the complete immersion of the water droplet into the nanofolds, the adhesive force would decrease resulted from the solid- liquid contact area reduction. Therefore, the high adhesive force is mainly caused by the micro- and nano- scaled structure.

关 键 词：阵列凹坑结构 水滴黏附力 拉伸 微米结构 纳米结构 

分 类 号：O647[理学—物理化学]