In the chemical industry, there is a strong demand for achieving carbon neutrality and promoting the circular use of resources. Utilizing basic chemicals like olefins effectively is a highly efficient approach to meet these goals. We are advancing the development of new materials focused on sustainability and the circular economy. As part of this effort, we are developing a new thermoplastic elastomer (TPE) primarily composed of ethylene, specifically an ethylene/styrene/ butadiene terpolymer (ESB). TPEs are plastic materials that exhibit rubber-like softness without requiring special treatments to maintain these properties. This characteristic makes TPEs excellent materials for saving resources and energy. The structure of ESB can be freely controlled by adjusting the proportions of the materials used, the reaction conditions, and the catalysts (substances that facilitate chemical reactions). This control over the structure significantly influences the properties of ESB, such as strength, self-healing capability, and degradability. Consequently, this provides new guidelines for developing innovative materials. This paper aims to provide a clear and comprehensive explanation of how ESB is designed and how its molecular design influences its material properties.