Session FC12 - Adhesion.
ORAL session, Monday afternoon, March 22
Room 268W, GWCC
Recently, there has been much research activity in the area of single molecule force spectroscopy(SMFS); i.e. the probing of the structure-property relationships of individual macromolecular chains. Most of the work to date has concentrated on the elasticity of biological systems (e.g. DNA, Titin, Xanthan, etc.). In this talk, we will discuss how we have used this method to study the mechanics of synthetic polymers such as polystyrene (PS) and poly(methacrylic acid) (PMAA). Generally, a mixed self-assembling monolayer technique is utilized to reduce the chain grafting density and covalently fix one chain end to a substrate. Force spectroscopy experiments are then carried out with the atomic force microscope in which single chains are tethered to a Si_3N_4 probe tip via non-specific, physisorption interactions. Upon retraction of the probe tip from the surface, continuous, attractive peaks in the force versus distance profiles are frequently observed due to the entropic resistance of uncoiling of the individual chains. These peaks could be fit, for all chain bridging lengths, to the (inextensible) freely-jointed chain (FJC) model and from these datafits the statistical segment length estimated. We will also discuss how SMFS can provide quantitative information on the statistical nature of adsorption of single polymer chains.