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Reprocessable Polymer Networks Designed with Hydroxyurethane Dynamic Cross‐links: Effect of Backbone Structure on Network Morphology, Phase Segregation, and Property Recovery
Author(s) -
Chen Xi,
Li Lingqiao,
Wei Tong,
Torkelson John M.
Publication year - 2019
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201900083
Subject(s) - crystallinity , materials science , polydimethylsiloxane , crystallization , polybutadiene , morphology (biology) , small angle x ray scattering , phase (matter) , modulus , polymer , network structure , cross link , dynamic mechanical analysis , plateau (mathematics) , polymer network , chemical engineering , composite material , polymer chemistry , scattering , copolymer , chemistry , organic chemistry , mathematical analysis , physics , mathematics , optics , machine learning , biology , computer science , engineering , genetics
Polybutadiene (PB), poly(tetramethylene oxide) (PTMO), and polydimethylsiloxane (PDMS) networks are synthesized using relatively low wt% of dynamic hydroxyurethane cross‐links, and recovery of cross‐link density, network morphology, and properties are investigated as a function of reprocessing. PB and PTMO networks exhibit full recovery of rubbery plateau modulus, and thus cross‐link density, and tensile properties after multiple melt‐state recycling steps. PDMS networks exhibit a small loss in rubbery plateau modulus with reprocessing. Small‐angle X‐ray scattering reveals nanophase separation in PB and PDMS networks. Although PTMO networks are not nanophase separated, cold crystallization is observed, with crystallinity increasing after reprocessing because of chain alignment. This work establishes the effective use of hydroxyurethane cross‐links toward full property recovery in different networks and provides insights on the design of reprocessable networks with distinctive morphology and sustainability.