Concise and Efficient Self-Healing Cross-Linked Polyurethanes via the Blocking/Deblocking Reaction of Oxime Urethanes

Abstract

The development of self-healing polymers can extend the service life of polymer materials. However, it is still a challenge to prepare a polyurethane with high healing efficiency and maximum retention of the properties of polyurethane itself. In this research, we proposed a new scheme for the industrial production of self-healing polyurethane and successfully synthesized a self-healing polyurethane using diacetyl oxime as the chain extender and triethanolamine as the cross-linking agent. Oximeblocked isocyanates deblock at a higher temperature and regenerate oxime urethanes at a lower temperature, thereby achieving thermal reversibility and self-healing due to the concise and efficient thermal reversible reaction of oxime urethanes. Fourier transform infrared and differential scanning calorimetry experiments confirmed that the oxime urethanes in the polyurethane deblock efficiently at around 90 °C and re-block after the temperature is lowered. The process can be cycled at least three times. Microscopic observation confirmed that the cracks disappeared within 60−90 min at 90 °C. The tensile test shows that the synthetic DiO-c-PU has a self-healing efficiency of over 94% at 90 °C for 1.5 h, which is more efficient. From the results, it appears that DiO-c-PU has good self-healing properties.

Dynamic covalent polymers enabled by reversible isocyanate chemistry

“…121 Afterwards, a series of PU CANs with OUBs were successfully designed with robust repairable and recyclable properties. [122][123][124][125][126] Recently, a set of self-healing POU elastomers were synthesized by a one-pot catalyst-free polyaddition from DMG, IPDI, PTMG, and glycerol, exhibiting tailorable mechanical properties by regulating the degree of crosslinking to provide mechanical adaptations with different tissues. 127 The self-healing behavior was realized at room temperature because of dynamic OUBs and hydrogen bonds, as well as flexible soft segments and the suppressed crystallization by steric hindrance of IPDI.…”

High-strength, high-toughness, self-healing thermosetting shape memory polyurethane enabled by dual dynamic covalent bonds

“…2C. 31,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] The resilience performance of PU-SS-CN-12.5% was tested via cyclic tensile testing. Fig.…”

Stimuli-Responsive Self-Healing Luminescent Materials Based on Lanthanide Ions and Bipyridine Moieties

“…Luminescent metallo-supramolecular polymers derived from the coordination between ditopic ligands and lanthanide ions (Ln 3+ ) have been reported to exhibit superior self-healing behavior. − Unfortunately, their mechanical strength is insufficient for processing into self-standing films, which hinders their practical implementation in self-healing light-converting films. − The combination of dense coordination bonds and hydrogen bonds (H-bonds) within the polymer chain can endow the final products with intriguing self-healing properties and satisfactory mechanical strength. − Transition metal ions such as Zn 2+ , Cu 2+ , and Fe 3+ are commonly employed to coordinate with ligands attached to polymer chains, forming robust self-healing polymers. − Motivated by this concept, our group recently reported luminescent polymers through the coordination bonds between Ln 3+ and polymer ligands containing terpyridine as well as H-bonds among the polymer chains. These polymers exhibit high luminescence characteristics typical of lanthanide complexes, resulting from energy transfer from ligands to Ln 3+ , and promising mechanical strength alongside remarkable self-healing abilities due to the reversibility of the coordination bonds and H-bonds within these systems. , Furthermore, stimulus-responsive luminescence has been simultaneously achieved in certain instances. , In addition, the luminescence, self-healing, mechanical properties, and stimulus-responsiveness of these polymers can be conveniently modulated by altering the ligand moieties capable of coordinating with Ln 3+ and the structure of the polymer chain to which the ligands are tethered. , However, most luminescent polymers tend to lose their exceptional mechanical properties under high humidity as polymers with polar groups can absorb water and become easily plasticized. − Moreover, the transmittance of such polymers significantly decreases due to the presence of absorbed water, impeding their application in optical and display devices .…”