Changzhong Chen

Three crosslinked polyurethane copolymers were successfully synthesized as polymeric solid–solid phase change materials (SSPCMs) for thermal energy storage. These materials were fabricated utilizing trihydroxy compounds (glycerol, triethanolamine, and trimethylolethane) as chain extenders and polyethylene glycol (PEG) as the phase change functional segment. A comprehensive suite of characterization techniques was employed to investigate the chemical structures, thermal properties, and crystalline behaviors of the resulting SSPCMs. Fourier transform infrared (FTIR) spectroscopy confirmed the successful synthesis of the crosslinked polyurethane network. Polarizing optical microscopy (POM) and wide-angle X-ray diffraction (WAXD) analyses revealed that all three SSPCMs exhibit regular spherulitic morphologies with sharp diffraction peaks resembling those of pure PEG, although variations in spherulite size and diffraction intensity were observed among the samples. Differential scanning calorimetry (DSC) demonstrated the reversible latent heat storage and release capabilities of the synthesized SSPCMs, with a maximum endothermic enthalpy (ΔH_endo) of 115.7 J/g. Furthermore, thermal cycling tests and thermogravimetric (TG) analysis verified their exhibit excellent reusability, thermal reliability, and high thermal stability.

Unreactive C-H bond activation is a new horizon for frustrated Lewis pair (FLP) chemistry. This study provides a systematic assessment of the catalytic reactivity of recently reported intra-molecular FLPs on the activation of typical inert C-H bonds, including 1-methylpyrrole, methane, benzyl, propylene, and benzene, in terms of density functional theory (DFT) calculations. The reactivity of FLPs is evaluated according to the calculated reaction thermodynamic and energy barriers of C-H bond activation processes in the framework of concerted C-H activation mechanisms. As for 1-methylpyrrole, 14 types of N-B-based and 15 types of P-B-based FLPs are proposed to be active. Although none of the evaluated FLPs are able to catalyze the C-H activation of methane, benzyl, or propylene, four types of N-B-based FLPs are suggested to be capable of catalyzing the activation of benzene. Moreover, the influence of the strength of Lewis acid (LA) and Lewis base (LB), and the differences between the influences of LA and LB on the catalytic reactivity of FLPs, are also discussed briefly. This systematic assessment of the catalytic activity of FLPs should provide valuable guidelines to aid the development of efficient FLP-based metal-free catalysts for C-H bond activation.

Since heavy metal ion-contaminated water pollutionis becoming a serious threat to human and aquatic lives, new methods for highly efficient removal of heavy metal ions from wastewater are important to tackle environmental problems and sustainable development. In this work, we investigate the removal performances of heavy metal copper (II) ions from aqueous solutions using a gas hydrate-based method. Efficient removal of heavy metal copper (II) ions from wastewater via a methane hydrate process was demonstrated. The influence of the temperature, hydration time, copper (II) ions concentration, and stirring rate on the removal of heavy metal copper (II) ions were evaluated. The results suggested that a maximum of 75.8% copper (II) ions were removed from aqueous solution and obtained melted water with 70.6% yield with a temperature of −2 °C, stirring speed 800 r/min, and hydration time of 4 h with aninitial copper concentration of 100 mg/L. The initial concentration of copper (II) ions in the aqueous solution could be increased to between 100 and 500 mg/L. Meanwhile, our study also indicated that 65.6% copper (II) ions were removed from aqueous solution and the yield of melted water with 56.7%, even with the initial copper concentration of 500 mg/L. This research work demonstrates great potential for general applicability to heavy metal ion-contaminated wastewater treatment and provides a reference for the application of the gas hydrate method in separation.

A linear polyurea (LPU) and a crosslinked polyurea (CPU) were respectively synthesized by condensation between 4,4′‐diaminodiphenyl methane and multivariate isocyanates, and then were used as supporting material to load polyethylene glycol (PEG) for shape‐stabilized phase change materials (ssPCMs). LPU has an incompact flocculent morphology with higher surface area and pore volume than CPU, and CPU is composed of contiguous bead particles with many interspaces. The shape stability of PEG/CPU ssPCMs is better than that of PEG/LPU ssPCMs with the same PEG mass fraction due to the different molecular interactions between PEG and the polymer matrix. The maximum PEG mass fraction in PEG/LPU and PEG/CPU ssPCMs LPU are 65% and 75%, respectively, and the corresponding melting phase change enthalpies are 82.66 J/g and 98.13 J/g, respectively. The heat storage efficiency of PEG/CPU ssPCMs is smaller than that of PEG/LPU ssPCMs with the same PEG content, caused by the greater movement restriction of PEG chains from the crosslinked network of CPU. The prepared ssPCMs have favorable reusability after 100 heating–cooling thermal cycles and have good thermal stability below 250°C, which is helpful to widen extent of application for latent heat storage.

A comprehensive review on electrospinning block copolymers.

A copper-mediated intramolecular aerobic oxidative cyclization of alkynes and sulfonylcrotonates to a variety of highly functionalized naphthyl ketones was developed.

The polyurethaneurea-based polymeric solid–solid phase change materials with different crosslinking density were firstly synthesized and characterization for thermal energy storage.