Wei Xu,Ruoyu Zhang,Wei Liu,Jin Zhu,Xia Dong,Hongxia Guo,Guo-Hua Hu
Shape memory thermoplastic polyurethane (SMTPU) containing isophorone diisocyanate (IPDI) in hard segment has excellent shape recoverability even after large strain deformation. However, the underlying mechanism of shape recovery remains unclear. In this study, 1,4-phenylene diisocyanate (PPDI) in the polyurethane is gradually substituted by IPDI, and multiscale effects are examined by normal and dichroic Fourier transform infrared spectroscopy (FTIR), small-angle X-ray scattering (SAXS), single-molecule force spectroscopy (SMFS), and mechanical test. Contradictory to the traditional conclusion, the degree of microphase separation decreases as the content of IPDI increases, while the macroscopic shape recoverability is largely improved. With dichroic FTIR and SAXS, we find that the morphology of hard phases changed from lamellar-like to fibrillar-like, which is more stable under stretching. SMFS experiments discover that IPDI could increase the elasticity of polymer chain and could endow the hard phases with “elastic” under stress. With these two factors, we are able to explain the high recoverability of the SMTPU containing IPDI.
Lithium-ion batteries (LIBs) with high-nickel ternary material cathode can provide a high specific capacity but are more sensitive to the H 2 O/HF contents and functional additives in the electrolyte. In this work, 1,4-phenylene diisocyanate (PPDI) is developed as an H 2 O/HF scavenger and film-forming electrolyte additive to enhance the performances of pouch LiNi 0 · 6 Co 0 · 2 Mn 0 · 2 O 2 (NCM622)/graphite batteries. Compared with batteries containing the blank electrolyte, the electrochemical performances of batteries with the PPDI-containing electrolyte can be significantly improved. Thereinto, after 600 cycles at room temperature (25 °C) and 300 cycles at high temperature (45 °C), the capacity retentions for the batteries with the PPDI-containing electrolyte are 84.9% and 81.3% at 1C, while the rates for the batteries with the blank electrolyte are only 29.3% and 14.4%, respectively. With the aid of theory calculations and spectroscopic characterization, the reasons behind the performance enhancement are elucidated, and the reaction mechanism of PPDI and H 2 O/HF is proposed. It is demonstrated that PPDI can scavenge H 2 O/HF in the electrolyte and form stable and highly conductive films on two electrodes to stabilize NCM622 and improve battery performances. Besides the functionalized electrolyte, this work can also inspire new ideas to develop functionalized electrolytes for high-performance NCM622-based LIBs.
Dawei Xiang,Manying Zhu,Yuefeng Chen,Shixing Wang,Zhengwu Peng,Dekun Zhang,Likang Fu
Gold is a widely used non-renewable resource, and its recycling is the key to solve the problem of dwindling gold resources. In this study, a novel covalent organic framework adsorbent (COF-pPDI@TAP) is developed for efficient Au(III) capture. The synthesis of the adsorbent was confirmed by FTIR and XRD characterization. The adsorption performance of COF-pPDI@TAP was studied by batch adsorption experiments. The maximum adsorption of Au(III) by COF-pPDI@TAP reached 779.02 mg/g in the adsorption experiments. Kinetic and isotherm results show that the adsorption is a monolayer chemisorption process controlled by particle diffusion. The positive value of ΔH indicates that COF-pPDI@TAP needs to absorb energy to maintain the reaction during the adsorption of Au(III), and the reaction is endothermic. In addition, COF-pPDI@TAP maintained a very high adsorption efficiency after five cycles of experiments, and could selectively capture Au(III) from different concentrations of polymetallic solutions. COF-pPDI@TAP has excellent anti-interference ability and good reusability. It is demonstrated by zeta potential, XRD, XPS and FT-IR that electrostatic interaction, chelation and reduction occurred during the adsorption process. These studies demonstrate the value of COF-pPDI@TAP for gold recovery applications.
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