Viscoelastic Property Mapping with Contact Resonance Force Microscopy

Abstract

We demonstrate the accurate nanoscale mapping of near-surface loss and storage moduli on a polystyrene-polypropylene blend with contact resonance force microscopy (CR-FM). These viscoelastic properties are extracted from spatially resolved maps of the contact resonance frequency and quality factor of the AFM cantilever. We consider two methods of data acquisition: (i) discrete stepping between mapping points and (ii) continuous scanning. For point mapping and low-speed scanning, the values of the relative loss and storage modulus are in good agreement with the time-temperature superposition of low-frequency dynamic mechanical analysis measurements to the high frequencies probed by CR-FM.

Contact resonance atomic force microscopy for viscoelastic characterization of polymer-based nanocomposites at variable temperature

“…r is obtained as the value in correspondence of which the two CRFs give the same contact stiffness, k * ( f n , r) = k * ( f m , r), neglecting the damping σ [34][35][36]. After calibration of the tip geometry and mechanical properties [37][38][39], knowledge of α and β allows one to evaluate the sample storage and loss moduli, E and E , respectively [19,20]. Calibration procedure, however, is a source of uncertainty and is responsible for the lengthening of each measurement session.…”

“…Also, CR-AFM characterization of elastic modulus of polymer blends at different temperatures was demonstrated [16]. Moreover, a recent improvement of CR-AFM, the so-called contact resonance AFM for viscoelasticity (CRAVE) [17,18], has been recently improved to enable measurement and mapping of storage and loss moduli as well as of loss tangent of viscoelastic materials [19][20][21][22][23]. Also, CR-AFM was recently demonstrated for the mapping of loss tangent of polymer blends at variable temperature from room temperature to about 80°C [24].…”

Contact resonances of U-shaped atomic force microscope probes

“…In order for new material designs to be fully understood, measurements that can quantify behavior at appropriate scales, often down to the nanoscale, are required. The contact resonance atomic force microscope (CR-AFM) technique is a promising materials characterization approach, which can quantify the elastic [1][2][3][4][5][6][7][8][9] as well as viscoelastic [10][11][12][13][14][15][16] properties of materials with spatial resolution on the order of tens of nanometers. CR-AFM uses the vibration spectra of an AFM probe during vibrations for both the noncontact case, and when the tip is in contact with a sample.…”

“…More recently, Yuya et al 10,18 developed a method to find the viscoelastic properties of a sample from experiment by following a similar approach. CR-AFM is becoming well accepted for analyzing the properties of a wide variety of materials such as polymers, [11][12][13][14]16,18,23 biological materials, 16,25,26 composite materials, 27 dielectric materials, 28 metallic glass, 29 and metals. 6,8,9 It has shown great promise for many interesting problems especially those involving the interfaces of a multi-phase material.…”

Elastic modulus measurements at variable temperature: Validation of atomic force microscopy techniques

“…In I-AFM, force-distance curves are collected and analyzed to evaluate the sample Young's modulus using an approach similar to that used in standard DSI tests [13][14][15][16]. In CR-AFM, the resonance frequencies of the AFM cantilever in contact with the sample surface are measured and used to determine the local (visco)elastic properties of the sample [17][18][19][20]. Moreover, a CR-AFM setup has been recently proposed for mapping the elastic modulus of polymers, with Young's modulus values from a few megapascals to a few gigapascals, at controlled temperature ranging from room conditions to 150°C [21].…”