Product Code: ICA10_M508

Investigations on the Laser Induced Polymerization of Organic-Inorganic Hybrid Oligomers for Micro Stereo Lithography Applications
Authors:
Andre Neumeister, Laser Zentrum Hannover e.V. (LZH); Hannover Germany
Martina Carsjens, Laser Zentrum Hannover e.V. (LZH); Hannover Germany
Florian Pape, Leibniz Universitaet Hannover, Institut fuer Mikroproduktionstechnik (IMPT); Garbsen Germany
Lutz Rissing, Leibniz Universitaet Hannover, Institut fuer Mikroproduktionstechnik (IMPT); Garbsen Germany
Rainer Kling, Laser Zentrum Hannover e.V. (LZH); Hannnover Germany
Presented at ICALEO 2010

For Micro Stereolithography applications, the correlation between the curing degree and the hardness of UV curable oligomers after irradiation is investigated. Oligomer thin films are polymerized with focused laser radiation (355 nm) by using a custom made Micro Stereo Lithography apparatus. Low-viscosity hybrid oligomers containing 50 wt% of Ormocer® (with 1 wt% of Irgacure® 369 as photo initiator) and 50 wt% of a trifunctional acrylate co-polymer are used during this study. Fourier-Transformed Infrared-Spectroscopy (FTIR) is applied in order to identify the chemical structure of both liquid and laser polymerized thin films with main emphasis on the reactive side chains. The functional group conversion of polymerized samples is monitored as a function of the accumulated laser fluence. The curing degree of the oligomers is calculated by observing the degradation of the acrylate group double bonds (810, 1618, and 1634 cm-1) by using both the carbonyl (1718 cm-1) and aromatic (1592 cm-1) double bond vibrational modes as internal reference peaks. The maximum degree of cure of the oligomers is approximately 65 % for the trifunctional acrylate and 55 % for the Ormocer®. We observe a strong correlation between the curing degree and the hardness of the cured samples by using nanoindentation measurements.