Download surface science experiments involving the atomic force - K-REx

The term to the third power takes into account any off-end loading (overlap between filament
and cantilever) and the geometric term takes into account the tilt of the AFM cantilever. In this
equation, kAFM is the spring constant of the AFM and is determined by the thermal method,81 θ =
11o is the angle of the AFM cantilever, L is the length of the wire and is measured by scanning
electron microscopy (SEM), ΔL is the overlap between the AFM cantilever and filament
measured using the internal 10x AFM microscope having resolution of 437 nm per pixels.
InvOLSAFM is the sensitivity of the AFM cantilever when pushed against a hard surface as
previously described, and InvOLSSystem is the sensitivity of the combined system of the AFM
cantilever and nanowire when they are pushing against each other. A second paper is in
preparation with Paneru and Flanders7 demonstrating that this method is in excellent agreement
with a nanowire vibrational analysis which leads to an independent method of spring constant
determination of the PEDOT filaments.
2.7 Contact Angle and Contact Angle Hysteresis Measurements
Being able to measure the static contact angle and contact angle hysteresis of samples in
the experiments conducted is a necessity for characterizing the wettability, chemical
homogeneity, and chemical quality of a sample’s surface. The information gained from the static
contact angle shown in Fig. 2.5 describes how hydrophobic or hydrophilic it is while the contact
angle hysteresis describes how chemically/physically smooth the surface or surface coating is.223
A First Ten Angstroms 100 Series long range optical microscope has been used extensively
throughout this work to make these types of measurements
Fig. 2.5: Different degrees of wettability.
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