Session: Undergraduate Research in Polymer Science:

Re-processable polyurethanes can be accessed via incorporation of bulky amine blocked isocyanates. Herein, imidazole and triazole diamine azole-based blocking agents (DABs) were designed to form bulky amine/isocyanate dynamic covalent linkages. The dynamic network formulation included imidazole DABs, Desmodur N3300, and nonanol. Utilizing the DABs with commercially available isocyanates and plasticizers enables the design of commercially relevant covalently adaptable networks (CANs). Variable temperature nuclear magnetic resonance spectroscopy was used to determine the activation energy and equilibrium constants of the blocked isocyanate dissociation. Thermal gravimetric analysis, dynamic scanning calorimetry, and dynamic mechanical analysis were used to assess network properties and reprocessing capabilities (T_d, T_g, E, M_c, and T_v) of the initial and reprocessed material. Overall, the dynamic urethane networks were able to be iteratively melt pressed.

Figure 1. The thermally reversible dissociation scheme of polyurethane imidazole DABs.

Figure 1. The thermally reversible dissociation scheme of polyurethane imidazole DABs.

Catherine Sarantes

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