Self-Healable and Remoldable Transparent Polyurethane Film with High Dielectric Constant from the Synergistic Effect between Lithium Salt and Ionic Liquid

Low-temperature, ultra-fast, and recyclable self-healing nanocomposites reinforced with non-solvent silylated modified cellulose nanocrystals

Developing polymeric materials with remarkable mechanical properties and fast self-healing performance even at low temperatures is challenging. Herein, the polymeric nanocomposites containing silane-treated cellulose nanocrystals (SCNC) with ultrafast self-healing and exceptional mechanical characteristics were developed even at low temperatures. First, CNC is modified with a cyclic silane coupling agent using an eco-friendly chemical vapor deposition method. The nanocomposite was then fabricated by blending SCNC with matrix prepolymer, prepared from monomers that possess lower critical solution temperature, followed by the inclusion of dibutyltin dilaurate and hexamethylene diisocyanate. The self-healing capability of the novel SCNC/polymer nanocomposites was enhanced remarkably by increasing the content of SCNC (0-3 wt%) and reaching (≥99 %) at temperatures (5 & 25 °C) within <20 min. Moreover, SCNC-3 showed a toughness of (2498 MJ/m3) and SCNC-5 displayed a robust tensile strength of (22.94 ± 0.4 MPa) whereas SCNC-0 exhibited a lower tensile strength (7.4 ± 03 MPa) and toughness of (958 MJ/m3). Additionally, the nanocomposites retain their original mechanical properties after healing at temperatures (5 & 25 °C) owing to the formation of hydrogen bonds via incorporation of the SCNC. These novel SCNC-based self-healable nanocomposites with tunable mechanical properties offer novel insight into preparing damage and temperature-responsive flexible and wearable devices.

Polyurethanes Modified by Ionic Liquids and Their Applications

Polyurethane (PU) refers to the polymer containing carbamate groups in its molecular structure, generally obtained by the reaction of isocyanate and alcohol. Because of its flexible formulation, diverse product forms, and excellent performance, it has been widely used in mechanical engineering, electronic equipment, biomedical applications, etc. Through physical or chemical methods, ionic groups are introduced into PU, which gives PU electrical conductivity, flame-retardant, and antistatic properties, thus expanding the application fields of PU, especially in flexible devices such as sensors, actuators, and functional membranes for batteries and gas absorption. In this review, we firstly introduced the characteristics of PU in chemical and microphase structures and their related physical and chemical performance. To improve the performance of PU, ionic liquids (ILs) were applied in the processing or synthesis of PU, resulting in a new type of PU called ionic PU. In the following part of this review, we mainly summarized the fabrication methods of IL-modified PUs via physical blending and the chemical copolymerization method. Then, we summarized the research progress of the applications for IL-modified PUs in different fields, including sensors, actuators, transistors, antistatic films, etc. Finally, we discussed the future development trends and challenges faced by IL-modified PUs.

Highly Foldable, Super-Sensitive, and Transparent Nanocellulose/Ceramic/Polymer Cover Windows for Flexible OLED Displays

Polymer cover windows are important components of flexible OLED displays but they easily generate wrinkles because of their weak folding resistance. Increasing the polymer thickness can improve the folding resistance but it decreases the touch sensitivity. Thus, fabricating highly foldable and supersensitive polymer cover windows is still challenging. Here, by incorporating cellulose nanocrystals (CNCs) and zirconia (ZrO₂) into colorless polyimide (CPI), we developed a highly foldable and supersensitive hybrid cover window. Inspired by the theory of elasticity, we added rigid CNCs into CPI to improve the elastic modulus and hence the foldability. ZrO₂ was introduced to improve dielectric properties, which leads to improved touch sensitivity. After these modifications, the elastic modulus of the cover windows was increased from 1432 to 2221 MPa, whereas its dielectric constant was increased from 2.95 to 3.46 (@1 × 10⁶ Hz), resulting in significantly enhanced foldability and sensitivity. Meanwhile, because of the nano size of CNCs and ZrO₂, the hybrid cover windows exhibit excellent optical properties with the transmittance of ∼88.1%@550 nm and haze of 2.39%. With improved and balanced mechanical, dielectric, and optical properties, these hybrid cover windows overcome current cover windows' defects and could be widely used in next-generation flexible displays.

Basic Approaches to the Design of Intrinsic Self-Healing Polymers for Triboelectric Nanogenerators

Triboelectric nanogenerators (TENGs) as a revolutionary system for harvesting mechanical energy have demonstrated high vitality and great advantage, which open up great prospects for their application in various areas of the society of the future. The past few years have seen exponential growth in many new classes of self-healing polymers (SHPs) for TENGs. This review presents and evaluates the SHP range for TENGs, and also attempts to assess the impact of modern polymer chemistry on the development of advanced materials for TENGs. Among the most widely used SHPs for TENGs, the analysis of non-covalent (hydrogen bond, metal-ligand bond), covalent (imine bond, disulfide bond, borate bond) and multiple bond-based SHPs in TENGs has been performed. Particular attention is paid to the use of SHPs with shape memory as components of TENGs. Finally, the problems and prospects for the development of SHPs for TENGs are outlined.