TY - THES

T1 - Influence of Injection Molding Parameters and Aging on Geometry and Functionality of Plastic Targets for Mass Spectrometry

AU - Pöhl, Alexander

N1 - embargoed until 22-08-2015

PY - 2010

Y1 - 2010

N2 - Stability of the geometric dimensions and constant surface properties are crucial for targets used in matrix-assisted laser desorption/ionization mass-spectrometry (MALDI-MS). In this thesis research had to be done to examine how geometric and surface properties of polymeric MALDI-MS targets are influenced by parameters during injection molding as well as ambient conditions over time. First, the ability of simulation to accurately predict shrinkage was investigated. For this purpose, the absolute difference in predicted and actual shrinkage, as well as shrinkage trends during a parameter study were evaluated. These investigations were performed for a carbon-black filled polypropylene and an unfilled cyclo-olefin-polymer. Overall, the simulation results were not precise enough to satisfy the need for high geometric accuracy. Second, the two grades used for shrinkage evaluation, as well as steel- and gold-coated versions of the conductive polypropylene, were subjected to extensive aging tests. The goal was to investigate three different aspects during these tests. First, it was investigated whether the steel-coated design can be conditioned at higher temperatures to reach a contact angle level necessary for functionality faster than at room-temperature. Second, the life time of the target was evaluated and possible storage and transport conditions defined. Finally, the possibility of archiving at very low temperatures (-80 °C) was examined. For all these examinations, samples were exposed to temperatures ranging from -80 °C to 120 °C and up to 90 % rh humidity. Consequently, shrinkage, flatness, roughness, surface integrity, wetting behavior and adhesion of the coating were examined. The targets did not sustain any damage after long-term aging up to 80 °C. Additionally to the standard method at room temperature, three accelerated conditioning methods are recommended and no arguments against archiving at temperatures up to -80 °C were found.

AB - Stability of the geometric dimensions and constant surface properties are crucial for targets used in matrix-assisted laser desorption/ionization mass-spectrometry (MALDI-MS). In this thesis research had to be done to examine how geometric and surface properties of polymeric MALDI-MS targets are influenced by parameters during injection molding as well as ambient conditions over time. First, the ability of simulation to accurately predict shrinkage was investigated. For this purpose, the absolute difference in predicted and actual shrinkage, as well as shrinkage trends during a parameter study were evaluated. These investigations were performed for a carbon-black filled polypropylene and an unfilled cyclo-olefin-polymer. Overall, the simulation results were not precise enough to satisfy the need for high geometric accuracy. Second, the two grades used for shrinkage evaluation, as well as steel- and gold-coated versions of the conductive polypropylene, were subjected to extensive aging tests. The goal was to investigate three different aspects during these tests. First, it was investigated whether the steel-coated design can be conditioned at higher temperatures to reach a contact angle level necessary for functionality faster than at room-temperature. Second, the life time of the target was evaluated and possible storage and transport conditions defined. Finally, the possibility of archiving at very low temperatures (-80 °C) was examined. For all these examinations, samples were exposed to temperatures ranging from -80 °C to 120 °C and up to 90 % rh humidity. Consequently, shrinkage, flatness, roughness, surface integrity, wetting behavior and adhesion of the coating were examined. The targets did not sustain any damage after long-term aging up to 80 °C. Additionally to the standard method at room temperature, three accelerated conditioning methods are recommended and no arguments against archiving at temperatures up to -80 °C were found.

M3 - Master's Thesis

ER -