Polyrotaxane‐modified waterborne polyurethane based on H‐bonding and metal bonding with mechanically tough and self‐healability

• Published in: Journal of applied polymer science 2024-02, Vol.141 (6), p.n/a
• Main Authors: Ren, Mengqing, Wu, Zixin, Wu, Lili, Yu, Bing, Wu, Weilin, Liu, Baoying, Xiao, Shengqiang
• Format: Article
• Language: English
• Subjects: Bonding strength; Coordination; Cyclodextrins; Healing; Hydrogen bonds; Mechanical properties; Metal bonding; Modulus of elasticity; polyrotaxane; Polyurethane resins; self‐healing; Sliding; sliding motion; Tannic acid; Tensile strength; waterborne polyurethane
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.54911

The pulley structure has been widely employed to improve mechanical properties. Polyrotaxane‐based waterborne polyurethane (WPU) typically exhibits good tensile strength and Young's modulus. However, achieving outstanding self‐healability of polyrotaxane‐based WPU under mild conditions generally proves insufficient solely relying on host‐guest interactions. Herein, a strategy that constructs a triple synergy of host‐guest interaction, hydrogen bonds, and metal coordination bonds by sequentially introducing tannic acid (TA) and Fe3+ is proposed to prepare polyrotaxane‐based WPU with excellent mechanical performance and high self‐healable capability. Besides the reversible non‐covalent bonding contributing to intrinsic self‐healing, the unique sliding motion of WPU's molecule chain acts as a driving force, promoting efficient contact among reversible bonds. Notably, benefiting from the sliding motion of β‐cyclodextrin (β‐CD) along a chain, the dynamic reconstruction of hydrogen bonds and metal coordination bonds, the resulting supramolecular WPU exhibited a tensile strength of 46.05 MPa and a toughness of 130.30 MPa, with satisfactory self‐healing performance (tensile strength healing efficiency of more than 95%). This work enriches the self‐healing mechanism and expands the concepts for the design of resilient self‐healing environmentally friendly supramolecular WPU. The mechanical properties, self‐healing properties and self‐healing mechanism of representative samples are presented in the figure. Benefiting from the sliding motion of β‐cyclodextrin along a chain, the dynamic reconstruction of hydrogen bonds and metal coordination bonds, the WPU‐PPR‐TA‐Fe sample successfully achieves a balance between self‐healing and mechanical properties to a certian extent.