Two-Dimensional Structure of Self-Assembled Alkyl-Substituted Polyphenylene Dendrimers on Graphite

详细信息    查看全文

• 作者：Simona Loi ; Hans-Jü ; rgen Butt ; Christina Hampel ; Roland Bauer ; Uwe-Martin Wiesler ; and Klaus Mü ; llen
• 刊名：Langmuir
• 出版年：2002
• 出版时间：March 19, 2002
• 年：2002
• 卷：18
• 期：6
• 页码：2398 - 2405
• 全文大小：398K
• 年卷期：v.18,no.6(March 19, 2002)
• ISSN：1520-5827

文摘

Three types of polyphenylene dendrimers were demonstrated to spontaneously form stable, pinhole-freemonolayers on graphite with a complex two-dimensional structure (Loi et al. Macromolecules 2001, 34,3661). For this paper, we extended our study using four new dendrimers to draw more general conclusions.Monolayers were prepared by spin-coating and analyzed by atomic force microscopy. The dendrimersconsist of a core of twisted, interlocked benzene rings and an external shell of alkyl chains. All structuresobserved can be divided into three types which can coexist on one sample: (1) granular regions, whereindividual dendrimers could be identified in a glasslike phase, (2) diffuse, homogeneous regions, and (3)nanorod regions consisting of parallel rows of 5.1-5.9 nm spacing. Dendrimers with alkyl chains of differentlengths showed the same spacing between nanorods. This indicates that the alkyl chains are orientedparallel to the direction of the nanorods. In addition, some dendrimers form two-dimensional crystals ongraphite. The concentration of the solution and the adsorption energy are two important factors determiningwhich structure is formed.