New Kind of Thermoplastic Polyurea Elastomers Synthesized from CO₂ and with Self-Healing Properties

Abstract

To convert CO2 into valuable polymers is of great significance from the viewpoints of environmental and sustainable development, as polymers are among the most widely produced chemicals in the world greatly affecting human life. Herein, a kind of functional polymers, CO2-based polyureas, were successfully synthesized via condensation of CO2 with alicyclic isophoronediamine (IPDA) and linear trioxa-1,13-tridecanediamine (TTD). The synthesized CO2-based polyurea shows not only self-healing capabilities but also excellent mechanical properties. It is self-healable at room temperature and the superior mechanical properties of the tensile strength (6.6 MPa) and toughness (28.7 MJ m–3) can be recovered to 95%. These unexpected properties were demonstrated to result from the rich and varied hydrogen bonds in the polyurea molecular chain between urea moieties originating from alicyclic IPDA and linear TTD. The strength, arrangement, and density of the hydrogen bonds are controllable by adjusting the amount of IPDA and TTD, and thus the mechanical and self-healing properties can be optimized. Furthermore, the synthesized novel CO2-based polyureas exhibit excellent properties in the surface protection and energy absorption, and so we believe they will have potential applications in a wide field.

A self-healing and recyclable poly(urea-imine) thermoset synthesized from CO2

“…[2][3][4] In the past few years, many efforts have been made to transform CO 2 into polymers including polycarbonate, 5,6 polyurethane 7,8 and polyurea. [9][10][11] As important smart materials that can repair cracks and restore their comprehensive performance, self-healing polymer materials have received extensive attention in the past few years. [12][13][14] Based on the healing mechanisms, self-healing materials can be generally fabricated by either extrinsic or intrinsic methods.…”

“…The synthesized CO 2 -based polyurea could self-heal at room temperature and the mechanical properties such as tensile strength (6.6 MPa) and toughness (28.7 MJ m −3 ) could be recovered to 95%. 10 Furthermore, in order to improve the performance of the polymer (strength and Young's modulus or toughness), we synthesized a new, environmentally friendly, self-healing and recyclable CO 2 -based polyurethane-urea via reversible hydrogen bonds and Diels-Alder bonds. The CO 2 -based polyurethaneurea is a tough and self-healing thermosetting material with a tensile stress of 18.5 MPa, an elongation at break of 136% and a Young's modulus of 151 MPa.…”

A self-healing and recyclable polyurethane-urea Diels–Alder adduct synthesized from carbon dioxide and furfuryl amine

“…To date, a few types of self-healing and recyclable CO 2 -based polymeric materials have been reported. 10,[46][47][48] In 2016, Caillol and coworkers developed thermo-responsive CO 2 -based polyurethane by converting furfuryl glycidyl ether into a cyclic carbonate derivative and mixing it with dimaleimide-terminated polypropylene glycol and an appropriate diamine. The resulting polyurethane can return from a solid state to a liquid state due to the breaking of Diels-Alder adducts, which is desired for many thermoreversible material applications.…”

“…The synthesized CO 2 -based polyurea is self-healable at room temperature and 95% of the superior mechanical properties of tensile strength (6.6 MPa) and toughness (28.7 MJ m −3 ) can be recovered. 47 In the present work, we have further attempted to design a self-healing and recyclable CO 2based polymer with high strength properties by introducing stronger cross-linking bonds via the Diels-Alder reaction, in which stronger dynamic covalent bonds would provide superior mechanical strength and stability. The Diels-Alder reaction is one of the most promising reactions in self-healing polymer materials as reported in the literature.…”

Synthesis of Polyurea Thermoplastics through a Nonisocyanate Route Using CO2 and Aliphatic Diamines

“…Thus, extensive attention has been devoted to using environmentally friendly alternatives to toxic isocyanate for the synthesis of PUa thermoplastics via the nonisocyanate route. By now, the synthesis of isocyanate-free PUas and oligoureas (OUas) is possible by the direct utilization of CO 2 as a comonomer and the indirect utilization of CO 2 via such CO 2 -derived compounds as carbonates, − bis-carbamates, and urea derivatives. − In the direct utilization of CO 2 as a comonomer, CO 2 is polycondensed with diamines in the presence of catalysts like N -phosphonium pyridine salt, N -methylphosphoramidite/imidazole salt, alkali bases, , ionic liquids, and organic superbases , or under high temperature conditions (180 °C) without any catalysts. − For the nonisocyanate PUas synthesized directly from CO 2 , the average molecular weight is usually below 4000 g/mol due to water produced from polycondensation, which will affect the chemical equilibrium in a closed reaction system. ,, Their mechanical properties are not good because of their high crystallinity resulting from a rigid network of hydrogen bonds between the polymer chains. For example, a PUa sample synthesized from 1,6-hexamethylene diamine and CO 2 is a brittle material, for which the molecular weight is unable to be measured .…”