Associate Professor Torbjörn Pettersson
Major parts of my research have been dealing with surface interaction and surface modifications. I have a strong background in using and developing advance AFM techniques. AFM is an excellent tool to obtain measurement with high lateral resolution both regarding force measurements and surface topography and also excellent to measure small forces. Majority of my AFM work have been dealing with force or friction force measurements and to obtain reliably measurements I have worked a lot on calibration issues. To obtain the information that I want to get I have done some modification of the AFM hardware and made some external software’s to control the instrument and evaluate the obtained data.
The systems that have been studied are various types of polyelectrolytes including proteins and living cells. Different types of polyelectrolytes with various charge densities have been evaluated and single layered or multi-layered structures of polyelectrolytes or polyelectrolyte complexes or proteins have been tested as lubrication protectors adhesion modifiers or compatibilizer for composite materials. The amount of material adsorbed to different surfaces has mainly been characterized with QCM-D.
During the latest years I have focused my research on wood and wood components mainly on cellulose fibres and cellulose fibrils. Studying the defibrillation process, fibril modifications, joint formation and compatibility problem related to fibre incorporation fibres and fibrils in composite materials. I have been rebuilding our JKR-instrument (both hard¬ware and software), and made it semi-automated, with automated image analysis which have made it fully functional for air measurement. And we have used this instrument to measure the interactions between different wood bio polymers, e.g. lignin, hemicelluloses and cellulose.
My interest to surface interaction and surface chemistry started during my work at Akzo Nobel, prior to my University studies, where I worked with bitumen emulsions and adhesion promoters to increase the wetability of bitumen to various types of stones. This work started my curiosity on for example how emulsion works, and why different types of surfactants gave better results than others and how could these surfactants affect the wetting of bitumen, and also make the bitumen resist water better. This interest focused my undergraduate studies into physical chemistry and surface chemistry, and my diploma work was done at the Institute for Surface Chemistry, YKI. After my diploma work I was offered to do research related to digital printing to study adhesion of toner to paper and cellulose networks. During the time at YKI I had a lot of small and large contract research project related to pulp and paper in collaborations with industrial partners. During my PhD study at Surface chemistry, KTH, I could really focus my research, and had good use of my previously experience and knowledge on for example surface modifications and surface characterisation. After receiving my PhD degree I turned my research back into forest product related issues and fibres doing both fundamental research on surface modifications and method development and also various applied research.