Fast, quantitative and high resolution mapping of viscoelastic properties with bimodal AFM

Quantitative mapping of viscoelastic properties of soft matter with a nanoscale spatial resolution is an active and relevant research topic in atomic force microscopy (AFM) and nanoscale science characterization. The AFM has demonstrated its accuracy to measure the energy dissipated on a sample surf...

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Bibliographic Details
Published in:Nanoscale 2019-08, Vol.11 (32), p.15289-15297
Main Authors: Benaglia, Simone, Amo, Carlos A, Garcia, Ricardo
Format: Article
Language:English
Subjects:
Accuracy
Atomic force microscopy
Block copolymers
Coefficients
Computer simulation
Energy dissipation
Energy measurement
Mapping
Material properties
Microscopes
Microscopy
Modulus of elasticity
Parameters
Polymers
Relaxation time
Spatial resolution
Viscoelasticity
Viscosity
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Summary:Quantitative mapping of viscoelastic properties of soft matter with a nanoscale spatial resolution is an active and relevant research topic in atomic force microscopy (AFM) and nanoscale science characterization. The AFM has demonstrated its accuracy to measure the energy dissipated on a sample surface with an atomic-scale resolution. However, the transformation of energy dissipation values associated with viscoelastic interactions to a material property remains very challenging. A key issue is to establish the relationship between the AFM observables and some material properties such as viscosity coefficient or relaxation time. Another relevant issue is to determine the accuracy of the measurements. We demonstrate that bimodal atomic force microscopy enables the accurate measurement of several viscoelastic parameters such as the Young's modulus, viscosity coefficient, retardation time or loss tangent. The parameters mentioned above are measured at the same time that the true topography. We demonstrate that the loss tangent is proportional to the viscosity coefficient. We show that the mapping of viscoelastic properties neither degrades the spatial resolution nor the imaging speed of AFM. The results are presented for homogeneous polymer and block co-polymer samples with Young's modulus, viscosity and retardation times ranging from 100 MPa to 3 GPa, 10 to 400 Pa s and 50 to 400 ns, respectively. Numerical simulations validate the accuracy of bimodal AFM to determine the viscoelastic parameters. Quantitative mapping of viscoelastic properties of soft matter with a nanoscale spatial resolution is demonstrated by bimodal AFM.
ISSN:2040-3364
2040-3372
DOI:10.1039/c9nr04396a