拉伸微模塑制备低密度聚乙烯超疏水表面

Fabrication of LDPE Superhydrophobic Surface by Stretching Controlled Micromolding

以新鲜荷叶为原始模板制备聚二甲基硅氧烷（PDMS）软模板，并用该软模板在真空下热压得低密度聚乙烯（LDPE），冷却剥离得到LDPE超疏水薄膜。场发射扫描电镜（FE—SEM）显示其表面由细长乳突（长约30um）构成，接触角为154°±3．5°，水滴极易滚落，而常压下热压得到的薄膜表面乳突则短而粗（长约8～10μm），接触角仅137°±2．7°。短粗的乳突高度接近模板微坑的深度，证明细长乳突是在微模塑脱模时拉伸形成的。

PDMS templates were prepared by replica molding against fresh lotus leaves. Then low-density polyethylene （LDPE） was melted and pressed onto the featured surface of the PDMS template in a vacuum oven. After cooling to room temperature and being peeled off from the templates, polyethylene films with superhydrophobic surface were created. FE-SEM imaging shows that the superhydrophobic surface is consist of slim and high micro-papillas （about 30 gm）. The contact angle is 154°±3.5° and the water drops can easily skip down. While surface of LDPE films micromolded in general oven possess much lower papillas （8-10 μm） and the contact angle is 137°±2.7°. The height of lower papillas approaches the depth of microholes on PDMS templates demonstrating the higher papillas have been stretched longer from the holes of the template during separating operation.