CALCULATION OF THE YOUNG’S MODULUS OF AN ADSORBED POLYMER LAYER

 Polymer layers adsorbed to a surface or in a confined environment often change their mechanical properties. There is even the possibility of solidification of the confined layer. To judge the stiffness of such a layer, we used the Hertz model to calculate the Young’s modulus of the polymer layer in the confinement of AFM experiments with silicon nitride tip with a radius of curvature of R » 50 nm and a glass sphere attached to the cantilever R = 5 mm. Since there is no visible indentation of the layer in the AFM experiments, the layer is either penetrated very easily, or the indentation is too small to be seen in a force curve. The latter would be the case for a polymer layer with a Young’s modulus above 4 ´ 10⁸ Pa in case of an experiment with a silicon nitride tip and 4 ´ 10⁵ Pa in case of a glass sphere.