title: A Single Molecular Diels-Alder Crosslinker for Achieving Recyclable Cross-Linked Polymers.
abstract: A triol-functional crosslinker combining the thermoreversible properties of Diels-Alder (DA) adducts in one molecule is designed, synthesized, and used as an ideal substitute of a traditional crosslinker to prepare thermal recyclable cross-linked polyurethanes with excellent mechanical properties and recyclability in a very simple and efficient way. The recycle property of these materials achieved by the DA/retro-DA reaction at a suitable temperature is verified by differential scanning calorimetry and in situ variable temperature solid-state NMR experiments during the cyclic heating and cooling processes. The thermal recyclability and remending ability of the bulk polyurethanes is demonstrated by three polymer processing methods, including hot-press molding, injection molding, and solution casting. It is notable that all the recycled cross-linked polymers display nearly invariable elongation/stress at break compared to the as-synthesized samples. Further end-group functionalization of this single molecular DA crosslinker provides the potential in preparing a wide range of recyclable cross-linked polymers.
authors.affiliation: Key Laboratory of Functional Polymer Materials of Ministry of Education, College of Chemistry, Nankai University, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300071, P. R. China.
authors.forename: Shengli
authors.initials: S
authors.lastname: Chen
authors.affiliation: Key Laboratory of Functional Polymer Materials of Ministry of Education, College of Chemistry, Nankai University, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300071, P. R. China.
authors.forename: Fenfen
authors.initials: F
authors.lastname: Wang
authors.affiliation: School of Physics, Nankai University, Tianjin, 300071, P. R. China.
authors.forename: Yongjin
authors.initials: Y
authors.lastname: Peng
authors.affiliation: Key Laboratory of Functional Polymer Materials of Ministry of Education, College of Chemistry, Nankai University, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300071, P. R. China.
authors.forename: Tiehong
authors.initials: T
authors.lastname: Chen
authors.affiliation: Key Laboratory of Functional Polymer Materials of Ministry of Education, College of Chemistry, Nankai University, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300071, P. R. China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wu
authors.affiliation: Key Laboratory of Functional Polymer Materials of Ministry of Education, College of Chemistry, Nankai University, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300071, P. R. China.
authors.forename: Pingchuan
authors.initials: P
authors.lastname: Sun
mesh_terms: D003432:Cross-Linking Reagents; D061565:Cycloaddition Reaction; D036103:Nanotechnology; D011108:Polymers / Q000737:chemistry*; D011140:Polyurethanes / Q000737:chemistry
chemical_list: D003432:Cross-Linking Reagents; D011108:Polymers; D011140:Polyurethanes
keywords: Diels-Alder reactions; crosslinking; polyurethane; recycle; single molecular crosslinkers