2024 年 52 巻 5 号 p. 297-303
Cross-linking creates three-dimensional networks that significantly enhance the thermal, mechanical, and solvent-resistant properties of materials, making it a pivotal method for the preparation of functional polymer materials. In this article, the author summarizes our research focusing on dynamic network structures featuring reversible bond-exchange mechanisms, including supramolecular cross-links and dynamic covalent bonds. Unlike traditional chemically cross-linked polymers, these innovative materials exhibit unique relaxation behaviors in response to thermal and light stimuli, offering useful functions such as recyclability, healability, and reprocessability. A thorough understanding of fundamental properties is crucial for regulating these functions. Notably, the complex rheological properties of a recently developed class of dynamic covalent-bonded network materials known as vitrimers remain insufficiently understood. This article provides insights into tuning the relaxation properties of vitrimers and analyzes long-time scale rheology with a focus on the applicability and limitations of the time-temperature superposition principle, as well as deviations from the typical Williams-Landel-Ferry (WLF) dependence of shift factors.