Talks and Poster Presentations (with Proceedings-Entry):

G. Harakaly, C. Gorsche, K. Seidler, H. Reghunathan, P. Dorfinger, T. Koch, J. Stampfl, N. Moszner, R. Liska:
"Formation of tough photopolymer networks using addition fragmentation chain transfer: A viable concept for lithography based 3D printing";
Poster: 4th European Symposium of Photopolymer Science, Leipzig; 09-11-2016 - 09-14-2016; in: "ESPS 2016", (2016), P-55.

English abstract:
Additive manufacturing technologies enable the 3D structuring of materials with optional shape and size. With the utilization of lithography-based techniques the resolution and the writing speed are greatly improved. However, in lithography-based 3D printing the accessible materials are limited to crosslinking acrylate-based formulations, which are not achieving the mechanical and thermomechanical properties of commonly used engineering polymer parts due to their irregularly crosslinked network architecture. Moreover, highly reactive compounds with low shrinkage stress are needed to achieve sufficient printing speeds and polymer parts with improved mechanical properties.
To optimize the mechanical properties of the printed parts, formulations that form more defined network architectures are needed. Additives that regulate the radical curing process and thus shift the network formation towards a step growth-like mechanism can provide better mechanical properties of the final product.
Addition-fragmentation chain transfer agents (e.g. β-allyl sulfones[1], vinyl sulfonate esters[2]) have been implemented to regulate network formation of photopolymerizable resins. The chain transfer reagents were synthesized and tested regarding their photoreactivity and toughness in a dimethacrylate system. The resulting toughness of the polymers was greatly improved without inhibiting the polymerization process and first 3D parts of tough methacrylate-based materials were successfully fabricated.

Additive manufacturing technologies, tough photopolymer networks, lithography based 3D printing

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