Environmentally-Friendly Synthesis of Carbonate-Type Macrodiols and Preparation of Transparent Self-Healable Thermoplastic Polyurethanes

• Published in: Polymers Vol. 9; no. 12; p. 663
• Main Authors: Kim, Seon-Mi, Park, Seul-A, Hwang, Sung Yeon, Kim, Eun Seon, Jegal, Jonggeon, Im, Changgyu, Jeon, Hyeonyeol, Oh, Dongyeop X, Park, Jeyoung
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 30.11.2017; MDPI
• Subjects: Butanediol; carbonate-type macrodiols; Chemical synthesis; Diols; environmentally-friendly synthesis; Gelation; Mechanical properties; Molecular weight; Monomers; NMR; Nuclear magnetic resonance; Packing density; polycondensation; Polyurethane resins; self-healing elastomers; Separation; thermoplastic polyurethanes; Titration; Urethane thermoplastic elastomers; polycondensation; environmentally-friendly synthesis; carbonate-type macrodiols; thermoplastic polyurethanes; self-healing elastomers
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym9120663

Carbonate-type macrodiols synthesized by base-catalyzed polycondensation of co-diols and dimethyl carbonate as an environmentally-friendly route were subsequently utilized for the preparation of transparent and self-healable thermoplastic polyurethanes (TPUs) containing a carbonate-type soft segment. Three types of macrodiols, obtained from mono, dual and triple diol-monomers for target molecular weights of 1 and 1.5 kg mol , were analyzed by ¹H NMR integration and the OH titration value. Colorless transparent macrodiols in a liquid state at a room temperature of 20 °C were obtained, except the macrodiol from mono 1,6-hexanediol. Before TPU synthesis, macrodiols require pH neutralization to prevent gelation. TPUs synthesized by a solution pre-polymer method with 4,4'-methylene(bisphenyl isocyanate) and 1,4-butanediol as a chain extender exhibited moderate molecular weights, good transparencies and robust mechanical properties. Especially, the incorporation of 3-methyl-1,5-pentanediol within carbonate-type macrodiols enhanced the transparency of the resultant TPUs by decreasing the degree of microphase separation evidenced by ATR-FTIR and DSC. Interestingly, packing density of hard segments and the degree of microphase separation determined the self-healing efficiency of TPUs, which showed good performances in the case of sourced macrodiols from triple diol-monomers.