疏水高分子单链在疏水表面上吸附和扩散过程的分子动力学模拟.pdf

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1、物理化学学报(WuliHuaxueXuebao)374Acta．一Chim．Sin．2011，27(2)，374—378February[Article]、^，ⅥrⅥ，．whxb．pku．edu．cn疏水高分子单链在疏水表面上吸附和扩散过程的分子动力学模拟牟丹周奕含(枣庄学院化学化工系，山东枣庄277160；中国科学院长春应用化学研究所，长春130022)摘要：采用分子动力学模拟方法研究不同聚合度(^o的聚乙烯(PE)单链在Si(111)表面上的吸附和扩散行为．分别设置相对介电常数为1和78模拟无溶剂和不良溶剂环境．PE单链的

2、平衡吸附构象均呈现为二维吸附构象，但在这两种截然不同的环境中呈现不同的构象和动力学特征，说明溶剂环境对于疏水高分子单链在疏水表面上的吸附和扩散起到了很大的作用．吸附能与聚合度呈线性关系，单位链长的平均吸附能是一0．38kJ．mol～．另外，扩散系数(D)与聚合度之间的标度关系是D～^广。关键词：疏水高分子单链：疏水表面i：二维吸附构象：标度中图分类号：O641MolecularDynamicsSimulationoftheAdsorptionandDifusionofaSingleHydrophobicPolymerChain

3、onaHydrophobicSurfaceMuDanZHOUY_．Han(DepartmentofChemistryandChemicalEngineering,ZaozhuangUniversity,Zaozhuang277160,ShandongProvince,PR．China；ChangchunInstituteofAppliedChemistry,ChineseAcademyofSciences，Changchun130022，PR．China)Abstract：Theadsorptionanddifusionofp

4、olyethylene(PE)withdiferentdegreesofpolymerization(N)onasilicon(111)surfacewerestudiedbymoleculardynamicssimulations．Therelativedielectricconstantwasselectedtobe1and78tomimicavacuumandasolutionenvironment．respectively．Thechainswereallpresentastwo—dimensional(2D)adso

5、rptionconformationonthesurfacebutdiferentconformationsanddynamicpropertieswerefoundinthetwoabsolutelydiferentenvironments．Thisshowsthatthesolventplaysanobviousroleinthechainadsorptionanddifusionprocessesonahydrophobicsurface．Therelationshipbetweentheadsorptionenergy

6、andthedegreeofpolymerizationfoIlowsaIinearfunctionandtheaverageadsorptionenergypersegmentis一038kJ·tool～．Inaddition，thedifusioncoeficient(D)ofthesechainsscaleswiththedegreeofpolymerizationasN．KeyWords：Singlehydrophobicpolymerchain；Hydrophobicsurface；Two-dimensionalad

7、sorptionconformation；Scalinglaw1引言杂的行为．-，高分子单链在固体表面附近和表面上高分子单链的动力学行为取决于溶剂环境及高的行为与高分子本体的动力学行为会有很大的差分子单链的浓度，三维状态下会表现出来丰富且复异．高分子吸附在表面并形成薄膜的行为是现代材Received：September20，2010：Revised：December7，201O：PublishedonWeb：January5，2011．Correspondingauthor．Email：mudanjlul980@yahoo．c

8、orn．cn；Tel：+86．632—3785913．TheprojectwassupportedbytheScience—TechnologyFoundationforMiddle—AgedandYoungScientistofShandongProvince，China(