Multifunctional Thermoplastic Polyurea Based on the Synergy of Dynamic Disulfide Bonds and Hydrogen Bond Cross-Links

Abstract

Integrating the self-healing property with the shapememory effect is a strategy that extends the service lifetime of shape-memory materials. However, this strategy is inadequate to reshape and recycle through the self-healing property or liquidstate remoldability. For more types of damage, solid-state plasticity is needed as a complementary mechanism to broaden the reprocessing channels of smart materials. In this study, multifunctional thermoplastic polyureas cross-linked by urea hydrogen bonds are prepared, which possess the multipathway remodeling property. The shape transition can be triggered after heating above 65 °C. The synergistic effect of dynamic disulfide bonds and hydrogen bonds causes the thermoplastic polyureas to possess characteristics similar to those of associative covalent adaptable networks. Thus, the polyureas can repair the damage or reconfigure the shape at 75 °C in 15 min by solid-state plasticity, instead of going into a viscous flow state. Soft grippers with various shapes are prepared by integration of solid-state plasticity, and the structure and function of the grippers can be repaired. The integration of solid-state plasticity and the self-healing property broadens the paths of shape-memory polymers in recyclability and reshapability.

Facile method towards mono‐component polyurea composite coating with excellent mechanical properties and self‐recovery ability

“…Such microphase separation endows the polyurea with excellent physical and chemical properties. On the other hand, the existence of a large number of polar groups leads to the formation of strong hydrogen bonds in the polyurea matrix, which not only serve as weak sacrificial bonds help in dissipating energy and improving the mechanical performance, but also bring the polyurea with potential self‐healing ability 13–17 . Until now, despite significant efforts and advances have been made in preparing high performance and self‐healing polyurea coating, yet most of the work involves complex synthetic processes and techniques, which restricts the real‐world applications of polyurea coating in consideration of economic competitiveness and operability.…”

Rapid self-healing and tough polyurethane based on the synergy of multi-level hydrogen and disulfide bonds for healing propellant microcracks

“…The temperature dependence of stress relaxation can be fitted by Arrhenius eqn (1). 57 ln t = ln t 0 + E a (1) where E a is the activation energy, and R and T are the gas constant and absolute temperature, respectively. The activation energy of PU-C (60.3 kJ mol À1 ) was lower than other self-healing PU, which has been reported lately, 24,46,58,59 indicating that the energy barrier for the free movement of the molecular chain was lower (Fig.…”

Progress in Utilizing Dynamic Bonds to Fabricate Structurally Adaptive Self‐Healing, Shape Memory, and Liquid Crystal Polymers

“…Introducing dynamic bonds into the SMPs can cause the rearrangement of the network structures through dynamic reactions, thereby enriching the deformation characteristics of materials. Various dynamic bonds are introduced into the SMPs to impart the materials with more shape change modalities through network reconstruction, such as transesterification, [ 121–123 ] disulfide bonds, [ 124,125 ] DA bonds, [ 86,126 ] metal–ligand interactions, [ 127–129 ] and hydrogen bonds. [ 130,131 ]…”

“…Introducing dynamic bonds into the SMPs can cause the rearrangement of the network structures through dynamic reactions, thereby enriching the deformation characteristics of materials. Various dynamic bonds are introduced into the SMPs to impart the materials with more shape change modalities through network reconstruction, such as transesterification, [121][122][123] disulfide bonds, [124,125] DA bonds, [86,126] metal-ligand interactions, [127][128][129] and hydrogen bonds. [130,131] For example, Bowman and coworkers have utilized the photoinitiated addition-fragmentation chain transfer reaction to enable the rearrangement of the covalently crosslinked polymer network through photoinduced plasticity (Figure 5a).…”