Damage-Detectable and Self-Healable Photoluminescent Dual Dynamic Supramolecular Networks

Abstract

The development of self-healing polymers with the ability to identify the location of damage and to nondestructively detect whether the damage is healed is essential for the application of self-healing materials in actual products. Such an ability would allow the healing process to be carried out only on the damaged area and to be monitored in real time, ultimately enhancing the reliability of the self-healing properties of the products. Herein, we synthesized ureidopyrimidinone end-functionalized poly(ε-caprolactone) with pendant pyrene groups (Py-UPCL) and investigated its photoluminescent, mechanical, and rheological properties, in addition to its damage detection and self-healing behaviors. Nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy, capillary viscometry, and fluorescence spectroscopy revealed that Py-UPCL possesses a dual dynamic supramolecular network structure derived from UPy quadruple hydrogen bonding and pyrene excimerization. Py-UPCL exhibited superior mechanical properties compared to ureidopyrimidinone end-functionalized poly(ε-caprolactone) without pendant pyrene groups (UPCL) and compared to a simple mixture of UPCL with pyrene (Py/UPCL). This was attributed to the cross-linking structure of Py-UPCL formed through pyrene excimerization. In addition, the Py-UPCL film exhibited a healing efficiency of ∼98.7% under the healing condition of 100 °C for 20 min, and the healed status was maintained without any change in shape. Importantly, upon ultraviolet irradiation, the photoluminescent properties of Py-UPCL allowed the direct detection of microcracks that are not normally visible to the naked eye. Rheometry and fluorescence experiments showed that the UPy quadruple hydrogen bonds and pyrene excimers dissociated at 130 and 140 °C, respectively, thereby accounting for the stable healing behavior of Py-UPCL.

Pyrene‐Based “Turn‐On” Fluorescent Polymeric Probe with Thioacetal Units in the Main Chain for Mercury(II) Detection in Aqueous Solutions and Living Cells

“…Pyrene has won the favor of many scholars due to its good stability and long fluorescence lifetime, becoming the focus of scientific exploration and research on fluorescence probes. [49][50][51][52] Thioacetal-modified pyrene has been designed for selective signaling of Hg 2+ . [17,20] In the present study, a water-soluble polymeric pyrene-based polythioacetal (PTA-Py) with thioacetal units in the main chain is designed and synthesized via direct polycondensation of 3, 6-dioxa-1, 8-octanedithiol, 1-pyrene formaldehyde (Py-CHO) and mPEG2k-SH.…”

Tough and Recyclable Polybutadiene Elastomer Based on Quadruple Hydrogen Bonding

“…Introducing supramolecular interactions into polymer molecular chains is an effective method to construct recyclable 1,2-PB supramolecular elastomers. , Common supramolecular interactions include hydrogen bonding, − metal–ligand coordinate bonds, − host-guest interactions, , π–π stacking, , and ionic interactions. , Among these supramolecular interactions, hydrogen bonding interaction is an effective way to construct polymer cross-linking networks. Hydrogen bonds exist widely in nature and show outstanding contributions to biological activities such as DNA replication, protein folding, and molecular recognition benefiting from their dynamic reversibility .…”

“…However, due to the small bond energy of a single hydrogen bond, it is difficult to give materials good mechanical properties based on single and double hydrogen bonding. Quadruple hydrogen bonding formed by 2-Ureido-4­[1 H ]-pyrimidinone (UPy) has received enthusiastic attention because its effect can be comparable to some covalent bonds. ,− Interesting self-complementarity and strong association constant (>10 7 M –1 in chloroform and >10 8 M –1 in toluene) enable UPy units strongly dimerizing via the DDAA hydrogen bonds array . Therefore, UPy can be used as an effective functional unit to construct the supramolecular cross-linking networks .…”