Effects of hydrogen bonding on the micro-structure development and mechanical properties of a bulkpolymerized Polyurea are systematically investigated from the perspective of temperatures. A twostage temperature dependence of bidentate hydrogen bonding among hard domains, namely, slight dissociation from 85 degrees C to 165 degrees C and dramatic destruction above 165 degrees C,are revealed by Fourier transform infrared spectroscopy (FTIR). Morphology developments and mechanical properties also exhibit similar stages in consistent with hydrogen bonding evolution. At the first stage, even slight dissociation of hydrogen bonding can lead to the loss of long-range connectivity of hard domains, resulting in the decrease of "energy loss coefficient". At the second stage, dramatic destruction of hydrogen bonding above 165 degrees C facilitates the "coarsening" process, which undoubtedly poses the decline of physical cross-link density, leading to the steep decline of Young's modulus and rubbery plateau modulus in dynamic mechanical analysis (DMA). Multi-scale characterizations are employed during the investigation. (C) 2018 Elsevier Ltd. All rights reserved.