Description
Adsorption of polymers at surfaces is a central subject in polymer science with a great relevance for many applications related to surface functionalization, nanofabrication, fouling, colloidal stabilization, coatings and adhesives, etc. AFM based force spectroscopy approaches, which have been used with success to measure forces down to the level to single molecule interactions, have been used with success to study adsorption and binding strength, conformation, and supramolecular structure of surface attached polymers. In this presentation, following a short introduction into force spectroscopy by AFM, two examples will be used to show recent progress in this area obtained in our laboratories. First we present results related to measuring the isoelectric point (pI) of proteins immobilized at AFM probe surfaces, using designer reference substrates with controlled charge over a broad pH range [1]. This approach allowed us to determine pI values of still unsequenced adhesion proteins relevant for marine fouling, and available in minute amounts only. In the second example we focus on single polymer pull and show the first results related to direction dependence of the adhesion force for partially adsorbed chains, when the free end is pulled. We demonstrate direction-dependent chain pull and fingerprints in the adhesion force vs. pulling angle indicating adsorption-desorption transitions as a function of the pulling angle [2]. A short account on anticipated future developments will conclude the presentation.| Period | 20 Nov 2017 |
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| Held at | Dow Chemical Terneuzen |