title   
  

Nanoscale elastic modulus variation in loaded polymeric micelle reactors

Solmaz, Alim and Aytun, Taner and Deuschle, Julia K. and Ow-Yang, Cleva W. (2012) Nanoscale elastic modulus variation in loaded polymeric micelle reactors. Langmuir, 28 (28). pp. 10592-10596. ISSN 1520-5827

This is the latest version of this item.

Full text not available from this repository.

Official URL: http://dx.doi.org/10.1021/la3017722

Abstract

Tapping mode atomic force microscopy (TM-AFM) enables mapping of chemical composition at the nanoscale by taking advantage of the variation in phase angle shift arising from an embedded second phase. We demonstrate that phase contrast can be attributed to the variation in elastic modulus during the imaging of zinc acetate (ZnAc)-loaded reverse polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) diblock co-polymer micelles less than 100 nm in diameter. Three sample configurations were characterized: (i) a 31.6 μm thick polystyrene (PS) support film for eliminating the substrate contribution, (ii) an unfilled PS-b-P2VP micelle supported by the same PS film, and (iii) a ZnAc-loaded PS-b-P2VP micelle supported by the same PS film. Force–indentation (F–I) curves were measured over unloaded micelles on the PS film and over loaded micelles on the PS film, using standard tapping mode probes of three different spring constants, the same cantilevers used for imaging of the samples before and after loading. For calibration of the tip geometry, nanoindentation was performed on the bare PS film. The resulting elastic modulus values extracted by applying the Hertz model were 8.26 ± 3.43 GPa over the loaded micelles and 4.17 ± 1.65 GPa over the unloaded micelles, confirming that phase contrast images of a monolayer of loaded micelles represent maps of the nanoscale chemical and mechanical variation. By calibrating the tip geometry indirectly using a known soft material, we are able to use the same standard tapping mode cantilevers for both imaging and indentation.

Item Type:Article
Subjects:Q Science > QC Physics
ID Code:19216
Deposited By:Cleva W. Ow-Yang
Deposited On:17 Aug 2012 10:58
Last Modified:17 Aug 2012 10:58

Available Versions of this Item

Repository Staff Only: item control page