Network Mesh Nanostructures in Cross‐Linked Poly(Dimethylsiloxane) Visualized by AFM

Viktoriia Drebezghova,G Julius Vancso,Ahmed Allal,Corinne Nardin,Hubert Gojzewski,Mark A Hempenius

doi:10.1002/macp.202000170

Abstract

AbstractMesh network structures are visualized by peak force tapping atomic force microscopy on cross‐linked poly(dimethylsiloxane) (PDMS) at the nanometer length scale. The images directly capture network mesh structures with mesh diameter values, from 10 to 16 nm at the free surface of PDMS. Perpendicular to the free surface, in cross‐sectional areas exposed by cryo‐fracturing, similar mesh structures are observed. When exposed to uniaxial stress, the circular mesh features become elongated, showing network deformation at the nanoscale, as a result of mechanical stress. Following Soxhlet solvent extraction the mesh‐like appearance remains unchanged, but mesh diameter values decrease, which are attributed to the removal of non‐crosslinked chains and silica filler.

Highlights

To cite this version: Viktoriia Drebezghova, Hubert Gojzewski, Ahmed Allal, Mark Hempenius, Corinne Nardin, et al
atomic force microscopy (AFM) measurements were performed on free PDMS surfaces that were cross-linked in direct contact with air
We embarked upon systematic studies using high resolution atomic force microscopy (AFM) in the peak force quantitative nanomechanical mapping (PF-QNM) mode to directly obtain quantitative information of the elastomer mesh morphology at the nanometer length scale

Summary

Results and Discussion

We examined the nanometer scale morphology of the PDMS surfaces with different cross-linker concentrations (2.5, 5, 20, and 25 wt%) by AFM. Mesh size distributions and their possible heterogeneities within the bulk of elastomers, in comparison with characteristics of the cross-linked surface in direct contact with air, would complement the analysis of structure and properties of PDMS for surface related applications. To tackle these challenges, we embarked upon systematic studies using high resolution atomic force microscopy (AFM) in the peak force quantitative nanomechanical mapping (PF-QNM) mode to directly obtain quantitative information of the elastomer mesh morphology at the nanometer length scale. We interpret the mesh size reduction by the leaching out of PDMS chains that were not covalently bound to the network, causing a mesh relaxation

Summary

Experimental Section

Conflict of Interest