Efficient, Room-Temperature Self-Healing Polyurethane Elastomers with Superior Tensile Properties and Solvatochromic Capacities

Abstract

Designing a polymeric elastomer that exhibits superior tensile properties, as well as efficient self-healing ability at mild temperatures, remains challenging. This study reports a polyurethane elastomer that contains imine and metal coordination bonds, by a facile method. The linear polyurethane (HPPU), bearing pendant ligands of phenolic oxygen and imine groups, originates via two-step polycondensation of hexamethylene diisocyanate, polytetrahedrofuran, and 2-{[(2-hydroxyphenyl) methylene]amino}-1,3-propanediol. Upon incorporation of Co(II) into the polymeric matrix, HPPU becomes an elastomer (HPPU-Co) with a physical crosslinked structure by the formation of metal coordination bonds. The dynamic reversible Co(II)−ligand coordination bonds in the structure impart the HPPU-Co elastomers with autonomous self-healing capacity at mild temperatures, and the tensile properties are adjustable by controlling the Co(II)/ligand ratio. When the mole ratio of Co(II)/ligand is 1:2, the as-prepared elastomer (HPPU-Co-1/2) exhibits superior tensile properties (ultimate tensile strength: 48.7 MPa; elongation at break: 1678%; fracture toughness: 287.7 MJ m −3 ) as well as self-healing abilities and repeated healing at room temperature [healing efficiency: 99.7% for the first healing and 81.2% for the sixth healing (24 h)]. Furthermore, the HPPU-Co elastomers exhibit reversible solvatochromic behaviors: the film color changes from blackish-green to red-brown upon dipping into water. The design concept in this work is an approach to preparing multifunctional polyurethane materials. The resultant polyurethane elastomers have multiple useful features and show promise for many fields that require long functional lifetimes.

Highly Adhesive and Tough Thermoplastic Polyurethanes Using a Furandicarboxamide Rigid Chain Extender with Noncovalent Interactions

“…The material exhibited excellent tensile strength, toughness, and self-healing properties at room temperature. Recently, some works on introducing special dynamic bonds including hydrogen bonds, − disulfide bonds, , metal–ligand coordination, , etc., into the PU molecular chain through the chain extender to achieve reinforcement, toughening, and special applications of materials have received extensive attention.…”

Regulating the structure of thermoplastic polyurethane elastomers with a diol chain extender to strength performance

“…The graphs of the percentage mass loss over time showed two different stages of mass loss. The first decomposition in the range of 300.9–383.7°C was attributed to the breaking of urethane bonds 40 . Differently, the initial degradation temperature raised from 300.9 to 313.0°C and the degradation temperature of 5% loss increased from 324.9 to 332.1°C as the regularity of hard segment improved, indicating better thermal stability for BMB‐TPU.…”

“…The first decomposition in the range of 300.9-383.7 C was attributed to the breaking of urethane bonds. 40 Differently, the initial degradation temperature raised from 300.9 to 313.0 C and the degradation temperature of 5% loss increased from 324.9 to 332.1 C as the regularity of hard segment improved, indicating better thermal stability for BMB-TPU. The second stage in the range of 383.7-450.0 C showed a significant weight loss contributed by the cleavage of the ether bonds in soft segments.…”

Enhanced hemocompatibility and antibacterial activity of biodegradable poly(ester-urethane) modified with quercetin and phosphorylcholine for durable blood-contacting applications

“…The case meant a certain energy dissipation from the bond fracture. 46 In addition, the UTS and FT of the QC-containing PEU-PQs enhanced rapidly with the increase of QC content, while the EBA decreased slightly. For example, PEU-P 0.5 Q 0.5 film, which had the optimum QC and PC content, had a UTS of 31.9 MPa, an EAB of 732%, and an FT of 76.1 MJ m À3 .…”