Aza Michael addition where the Michael acceptor and nucleophile is an acrylate and amine respectively, has been identified as a type of click chemistry capable of forming polymers without producing undesired side products. As such, this reaction is potentially useful for two-part reactive additive manufacturing methods, such as reactive extrusion. As additive manufacturing is a layer by layer processes deposition of one layer upon another necessitates the ability of the initial layer to resist deformation (i.e., creep, extension or collapse) upon subsequent layer addition. Thus, harmonious balance between kinetics, rheology and build rates must be maintained. Optimization of the nucleophile and Michael acceptor stoichiometry aids to obtain not only sufficient kinetics to cure rapidly during printing, but also to vary properties from structurally rigid to rubbery polymeric networks. Employing aliphatic vs. aromatic and/or sterically hindered vs. unencumbered Michael acceptor or nucleophile allows for tuning of the polymeric properties ranging from soft and rubbery to structurally rigid and stiff. Catalyst, temperature, and stoichiometric ratios between nucleophile and Michael acceptor are under investigation to understand reaction kinetics and extent of cure. Structure reactivity relationship of the Michael acceptor and nucleophile will be analyzed through measurement of rheological, thermal, and mechanical properties of these thermosets.

Aza Michael addition for additive manufacturing of rigid and rubbery polymers

2019 Spring National Meeting

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