Direct Measurements of Polyelectrolyte Brush Responses using Atomic Force and Optical Microscopy

In this thesis, so-called ”polyelectrolyte brushes” are addressed. The focus is on the investigation and understanding of the response properties of these polymer surfaces. For that purpose new methods are developed which combine force spectroscopy and optical microscopy. As well, established physico-chemical techniques are used. Polymer brushes provide an excellent building block for responsive surfaces. Surface properties that can be triggered are for example adhesion, charge, friction, stiffness,optical properties, porosity, or biocompatibility. This can be obtained by changing the environment, and by external stimuli. For this reason, such systems are ideal for the rational design of sensors and actuators. This thesis bridges from fundamental polymer chemistry (chemistry of polymer brushes) over physics (contact mechanics, adhesion, and polymer physics) to potential applications (sensors and actuators). Scientific input has been provided for the research on polymer brushes, mechanoresponsive systems, force sensing, and active materials, as well as contact mechanics, colloidal arrangement, and (bio) adhesion. In particular, the soft colloidal probe (SCP) force spectroscopy has been developed. This technique improves massively the sensitivity for the investigation of adhesion energy of soft surfaces. Also, this method has been used to investigate the pressure sensitivity of mechanoresponsive surfaces that have been developed in this work. This mechanoresponsive polymer layers change their optical properties as a function of applied pressure. This allows to detect stress distributions with high spatial and high stress resolution. In addition, these surfaces have been used to study bioinspired adhesion (Gecko adhesion). Finally, responsive polymer brush systems are characterized with regard to their structure -property relationships. Interaction and mechanical properties have been characterized and physical models have been developed to describe the observed phenomena. For these responsive polymer layers potential applications are presented.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Bayreuth

Year

2013

Author dc:creator

• Erath, Johann

Contributors dc:contributor

• Fery, Andreas

Repository record source_url

https://epub.uni-bayreuth.de/id/eprint/28/

OAI identifier oai:identifier

oai:epub.uni-bayreuth.de:28