Dendronized hyperbranched polymer (DHP) combining the structure of a dendrimer and a hyperbranched polymer, is a new kind of polymer, with some advantages as summarized from the few examples reported so far. Herein, three second-order nonlinear optical (NLO) functional dendronized hyperbranched polymers, DHP-NN, DHP-NS and DHP-SS, were prepared in satisfactory yields through the click chemistry reaction, by using two kinds of low generation dendrimers as the monomers. Due to its particular branched structure, these DHPs with high molecular weights exhibit good solubility, processability, and good nonlinear optical performance. All the DHPs can keep their NLO performance at relatively high temperatures (∼100°C). In particular, the introduced isolation chromophore could further enhance the thermostability of the NLO performance: DHP-NS and DHP-SS exhibit no obvious decay of their NLO coefficient when the thin films are heated to 125°C. † Electronic supplementary information (ESI) available: The detailed synthesis and characterization of monomers and polymer LineD-NS; NMR spectra, UV-vis spectra, TGA thermograms; UV-vis spectra of thin films before and after poling. See Scheme 2 (a) Synthesis of HP-r from reference; (b) synthesis of DHP-NS in this work. Polymer Chemistry PaperThis journal is

A larger NLO effect with NLO coefficient of 195.2 pm V−1 was achieved with 3D-extended conformations, even with only 9 chromophore moieties in the dendrimer.

Thermal batteries with a high power density and rapid activation time are crucial for improving the fast response ability of sophisticated weapons. In this study, an Ni-NiCl2 composite was prepared via hydrogen reduction and employed as a cathode material. Discharge tests on a battery assembled using the fabricated composite revealed that its initial internal resistance decreased and the activation time reduced. Notably, the Ni-NiCl2 cathode increased the energy output by 47% (from 6.76 to 9.94 Wh in NiCl2 and Ni-NiCl2, respectively) with a cut-off voltage of 25 V; the power density of the novel battery system reached 11.4 kW/kg. The excellent performance of the thermal battery benefited from the high electrode potential and low internal resistance of Ni-NiCl2. This study contributes to the development of high-performance electrode materials for next-generation thermal battery-related technologies.

For the first time, two nonlinear optical (NLO) main chain dendronized polymers, MDPG1 and MDPG2, were prepared through the Suzuki coupling reaction by utilizing low-generation dendrimers as the monomers. These polymers inherit the advantages of both main chain polymers (which usually demonstrate good stability of the NLO effect) and dendronized polymers (which usually possess a large NLO coefficient) simultaneously. For MDPG2, its NLO coefficients d 33 value and d 33(∞) value are up to 116 and 20 pm/V, respectively, very similar to those of the normal dendronized polymer DPG2. Interestingly, thanks to its main chain structure, the onset temperature for the decay of its d 33 value was tested to be 100°C, 30°C higher than that of DPG2. ■ INTRODUCTIONOrganic/polymeric nonlinear optical (NLO) materials have attracted considerable interest in the past decades because of their huge potential applications in frequency doublers, optical storage devices, and electro-optic (EO) switches and modulators. 1−5 For practical applications, it is very important to keep their large optical nonlinearities, usually derived from the poling-induced noncentrosymmetric alignment of chromophore moieties under an electric field (the graphical illustration of poling procedure was presented in Figure S1, Supporting Information) for a long time. 6−10 From this standpoint, main chain NLO polymers would be good potential candidates, since they usually demonstrated stable oriented dipoles at elevated temperatures. However, as the chromophore moieties are directly incorporated into the polymer backbone in the main chain polymers, during the poling procedure under an electric field the required noncentrosymmetric alignment of chromophore moieties is very hard to be achieved due to the difficulty of the needed large segmental motions of the polymer backbone, leading to the relatively low poling efficiency. Therefore, the main chain NLO polymers usually demonstrated good stability for the noncentrosymmetric alignment of chromophore moieties but very low NLO coefficients. 11−16 Meanwhile, the relatively bad solubility and processability of the main chain polymers were also the shortcomings for their real applications.On the other hand, dendrtic macromolecules, including dendrimers and hyperbranched polymers, etc., usually demonstrated much better solubility and processability than normal linear polymers, derived from their highly three-dimensional (3D) branched topological structure. 17−20 In the NLO field, this branched structure could further endow the polymer chains with favorable "site isolation effect" to the NLO chromophore moieties, which could minimize the strong intermolecular electrostatic interactions among NLO chromophore moieties and thus enhance the macroscopic optical nonlinearities. 21−25 Since 1987, by the attachment of the dendrimers to the linear polymeric backbone, scientists have designed a new dendritic architecture, namely, dendronized polymers, which usually merged the characteristic of both traditional dendritic macromolecu...

Pt-containing catalysts are currently used commercially to catalyze the conversion of carbon monoxide (CO) and hydrocarbon (HC) pollutants from stationary chemical and petroleum plants. It is well known that Pt-containing catalysts are expensive and have limited availability. The goal of this research is to find alternative and less expensive catalysts to replace Pt for these applications. This study found that niobium oxide (Nb 2 O 5 ), as a carrier or support for certain transition metal oxides, promotes oxidation activity while maintaining stability, making them candidates as alternatives to Pt. The present work reports that the orthorhombic structure of niobium oxide (formed at 800 • C in air) promotes Co 3 O 4 toward the oxidation of both CO and propane, which are common pollutants in volatile organic compound (VOC) applications. This was a surprising result since this structure of Nb 2 O 5 has a very low surface area (about 2 m 2 /g) relative to the more traditional Al 2 O 3 support, with a surface area of 150 m 2 /g. The results reported demonstrate that 1% Co 3 O 4 /Nb 2 O 5 has comparable fresh and aged catalytic activity to 1% Pt/γ-Al 2 O 3 and 1% Pt/Nb 2 O 5 . Furthermore, 6% Co 3 O 4 /Nb 2 O 5 outperforms 1% Pt/Al 2 O 3 in both catalytic activity and thermal stability. These results suggest a strong interaction between niobium oxide and the active component-cobalt oxide-likely by inducing an oxygen defect structure with oxygen vacancies leading to enhanced activity toward the oxidation of CO and propane.