Single-pass Kelvin force microscopy and dC/dZ measurements in the intermittent contact: applications to polymer materials

Sergei Magonov,John Alexander

doi:10.3762/bjnano.2.2

Abstract

We demonstrate that single-pass Kelvin force microscopy (KFM) and capacitance gradient (dC/dZ) measurements with force gradient detection of tip–sample electrostatic interactions can be performed in the intermittent contact regime in different environments. Such combination provides sensitive detection of the surface potential and capacitance gradient with nanometer-scale spatial resolution as it was verified on self-assemblies of fluoroalkanes and a metal alloy. The KFM and dC/dZ applications to several heterogeneous polymer materials demonstrate the compositional mapping of these samples in dry and humid air as well as in organic vapors. In situ imaging in different environments facilitates recognition of the constituents of multi-component polymer systems due to selective swelling of components.

Highlights

Atomic force microscopy (AFM) applications include highresolution imaging, probing of local materials properties and compositional mapping of heterogeneous materials in different environments
The fluoroalkane structures are the useful models for the verification of Kelvin force microscopy (KFM) operations
The same is true for metal alloys because their surface potentials are directly defined by work function [8]

Summary

Introduction

Atomic force microscopy (AFM) applications include highresolution imaging, probing of local materials properties and compositional mapping of heterogeneous materials in different environments. The high sensitivity of the AFM probe to various materials properties is behind such visualization of individual components of complex materials. Compositional imaging of heterogeneous polymer materials is primarily based on differences of local mechanical and adhesive properties of their constituents. These differences are best reflected in phase images in the amplitude modulation (AM) mode, which are obtained at elevated forces. The phase contrast is efficient in differentiating the rubbery, glassy and inorganic components of polymer blends and composites, its interpretation in terms of specific mechanical properties is extremely difficult. The quantitative analysis of local mechanical properties of even neat poly-

Methods

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Conclusion