Organic–Inorganic Linear Segmented Polyurethanes Simultaneously Having Shape Recovery and Self-Healing Properties

Abstract

Double-decker silsesquioxane (DDSQ) and hindered urea bonds were simultaneously introduced into the main chains of linear segmented polyurethane (PU) to synthesize organic–inorganic linear segmented poly­(urea urethanes) (PUUs). The organic–inorganic PUUs were microphase-separated, and the POSS cages were aggregated into the microdomains with the size of 10–20 nm. The organic–inorganic PUUs had the improved thermomechanical properties in comparison to those of the control PU. Notably, the strong physical cross-linking was formed in the organic–inorganic PUUs, and thus the materials could display the properties of thermoset elastomers. The physical cross-linking was attributable to the formation of POSS microdomains, which acted as the nano-cross-linking sites. Owing to the formation of physical cross-linking, the shape memory properties have been imparted to the organic–inorganic nanocomposites; the fixing of temporary shapes and the recovery of original shapes were significantly improved. The inclusion of hindered urea bonds provided the organic–inorganic PUUs with the solid-state plasticity at room temperature (i.e., self-healing properties) via the dynamic exchange of hindered urea bonds. It was found that the nanoreinforcement of POSS microdomains did not significantly decrease the self-healing properties of the organic–inorganic PUUs. This work reports an approach simultaneously to optimize the shape memory and self-healing properties of polyurethanes.

Self-Healable Reprocessable Triboelectric Nanogenerators Fabricated with Vitrimeric Poly(hindered Urea) Networks

“…Furthermore, poly­(hindered urea) (PHU) networks are degradable and less costly when synthesized by a facile step-growth polymerization of various polyamines including multifunctional bulky amines with polyisocyanates. Several reports have described the development of cross-linked poly­(urea-urethane) and PHU vitrimers to achieve thermal malleability and recyclability. − Moreover, reports have explored the use of silsesquioxane, bisphenol S, and a three-arm star isocyanate , that react with a difunctional hindered amine ( N , N -di­( tert -butyl)­ethylenediamine) and the synthesis of a methacrylate bearing t -butylamine pendants . Despite these advances, the development of a robust approach is required for the fabrication of PHU networks with enhanced mechanical properties as well as excellent self-healability and processability.…”

β-Lactamase Responsive Supramolecular Hydrogels with Host–Guest Self-Healing Capability

“…We observed that as-made hydrogels exhibited initial tensile moduli of ∼815 kPa, which is among the strongest supramolecular hydrogels with healing ability as compared with other recently reported self-healing materials with comparable healing times (Table S1). − We found that upon severing the hydrogels and healing for 24 h, the initial tensile modulus was similar at 785 ± 40 kPa.…”

Dynamic Covalent Polyurethane Network Materials: Synthesis and Self‐Healability

“…[ 115 ] Rowan and coworkers studied the impact of steric hinderance of N ‐alkyl substituents and network connectivity in poly(alkylurea‐urethane) dynamic network films to guide the design and properties of dynamic hindered urea networks. [ 116 ] Further, the use of t‐butylamino group‐based bulky urea bond as N , N ‐di‐(tert‐butyl)ethylenediamine (a difunctional hindered amine) has been explored to fabricate various shape‐memory PHU networks containing bisphenol S, [ 117 ] silsesquioxane, [ 118 ] triisocyanate, [ 119 ] azidine, [ 120 ] and others. [ 121 ]…”