Measurement of adhesion energies and Young's modulus in thin polymer films using a novel axi-symmetric peel test geometry.

We present a novel method of probing adhesion energies of solids, particularly polymers. This method uses the axi-symmetric deformation of a thin spincast polymer membrane brought into contact with a flat substrate to probe the work of adhesion. The use of a thin membrane minimizes uncertainty in the radius of contact, while the use of spincast films provides very smooth surfaces by means of a very simple method. The experimental profile of the deformed membrane shows good agreement with the expected logarithmic profile. The experimental setup enables the measurement of Young's modulus and the solid-solid work of adhesion for thin films. The value obtained for Young's modulus of polystyrene (PS) was found to be in agreement with other conventional measurement techniques. In addition, measurement of the work of adhesion at the PS/silicon oxide interface was possible. The apparatus is well suited to studying the dependence of Young's modulus, work of adhesion and fracture energy on membrane thickness, temperature, pulling rate, and ageing of the interface, and can readily be modified to study biologically relevant samples.