以多孔CaCO_3微球为模板制备聚乙烯超疏水表面

Fabricating Polymer Superhydrophobic Surface by Porous Spherical CaCO_3 Particle Layer as Template

以聚苯乙烯磺酸钠(PSS)掺杂的多孔碳酸钙(CaCO3)微球层为模板,通过热压低密度聚乙烯(LDPE)并结合酸蚀刻的方法制得了具有多层黏连微球结构、而非常见蜂窝状多孔结构的LDPE稳定超疏水表面(接触角为152.8°±2.5°,滚动角约为6°).元素分析表明,表面黏连微球为纯LDPE而非LDPE包覆的CaCO3.将CaCO3微球稀疏地撒在LDPE表面并加热熔融,微球会自发沉降到熔体内部,酸蚀刻后形成了类似莲蓬的表面微结构,即坑内包含小球.结合CaCO3微球生成原理和多孔结构,可认为黏连微球结构和莲蓬结构均是由于LDPE熔融大分子自发沉积到多孔CaCO3微球内部,"反模"形成了LDPE微球所致.

A novel phenomena or surface microstructure formation mechanism was found during fabricating superhydrophobic polymer films by replica-molding method using porous spherical CaCO3 particle layers as templates.Polystyrene sulfonate（PSS） doped porous spherical CaCO3 particle suspension was first cast onto a glass substrate and dried towards forming a thin layer of particles.Then low-density polyethylene（LDPE） pellets were bestrewed onto such a CaCO3 particle layer.After the LDPE was heated to melt status（180 ℃）,another piece of glass plate pre-heated was covered on the LDPE melt for 10 min and then clamped together（3.5 kPa） with the glass substrate bearing the CaCO3 particle layer.After being cooled,peeled off from the glass substrate and rinsed with flowing water,the LDPE surface enwrapping porous spherical CaCO3 particles was obtained.Then it was further etched in 20% HCl solution for 10 min.After washing and drying,the LDPE film with superhydrophobic surface was created,with water contact angle up to 152.8°±2.5° and sli-ding angle ca.6°.Moreover,such superhydrophobicity was confirmed stable to continuous 30 μL water droplets free falling from 100 cm height.SEM imaging showed that completely different with honeycomb structures that were generally formed by soluble spherical particles as replica templates,conglutinated spherical particles structure were found on the LDPE surface.Moreover,nano structures were also found on each single spherical particle surface.Element characterizations by EDS and XRF both demonstrated that no Ca element existed on or blow herein microstructured LDPE surface.To elucidate the formation mechanism of conglutinated spherical particles structure,the LDPE smooth surface was first covered with sparse porous spherical CaCO3 particles,then heated to melt state and held for 30 min.After being cooled and thoroughly etched with HCl solution,the LDPE surface presented lotus seedpod like structure,e.g.,smaller spheres staying within larger holes.Such phenomena demonstrated that it was the spontaneous loading of hydrophobic melt LDPE macromolecules into PSS walled nano pores of CaCO3 microparticles that formed conglutinated spherical particles structure on LDPE surface.This find not only supplies a new method for fabricating polymer superhydrophobic films but also develops a novel strategy for expanding applications of porous spherical CaCO3 particles.