Synthesis of Self-Healing Polymers by Scandium-Catalyzed Copolymerization of Ethylene and Anisylpropylenes

• Published in: Journal of the American Chemical Society Vol. 141; no. 7; pp. 3249 - 3257
• Main Authors: Wang, Haobing, Yang, Yang, Nishiura, Masayoshi, Higaki, Yuji, Takahara, Atsushi, Hou, Zhaomin
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 20.02.2019
• Subjects: ambient temperature; catalysts; composite polymers; copolymerization; dry environmental conditions; ethylene; glass transition temperature; mechanical damage; mechanical properties; modulus of elasticity; molecular weight; scandium; separation
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.8b13316

Self-healing materials are of fundamental interest and practical importance. Herein we report the synthesis of a new class of self-healing materials, formed by the copolymerization of ethylene and anisyl-substituted propylenes using a sterically demanding half-sandwich scandium catalyst. The copolymerization proceeded in a controlled fashion, affording unique multi-block copolymers composed of relatively long alternating ethylene-alt-anisylpropylene sequences and short ethylene–ethylene units. By controlling the molecular weight and varying the anisyl substituents, a series of copolymers that show a wide range of glass-transition temperatures (T g) and mechanical properties have been obtained. The copolymers with T g below room temperature showed high elastic modulus, high toughness, and remarkable self-healability, being able to autonomously self-heal upon mechanical damage not only in a dry environment but also in water and aqueous acid and alkaline solutions, while those with T g around or above room temperature exhibited excellent shape-memory property. The unique mechanical properties may be ascribed to the phase separation of the crystalline ethylene–ethylene nanodomains from the ethylene-alt-anisylpropylene matrix.