A triptycene derived hypercrosslinked polymer for gas capture and separation applications

This work describes facile synthesis of a porous polymeric material ( T-HCP ) using readily available reagents. Specifically, T-HCP is a thermally stable and hypercrosslinked polymer (HCP) that is essentially microporous with a high BET specific surface area (940 m² g^?1). Triptycene based polymers are known to feature internal free volume. Thus, the incorporation of triptycene units and extensive crosslinking by an external cross-linker in T-HCP makes it a promising adsorbent for small gas capture applications. Experimental results show that T-HCP demonstrated good CO₂ capture capacity of 132 mg g^?1 (273 K, 1 bar). Molecular hydrogen storage capacity of T-HCP is estimated to be 17.7 mg g^?1 (77 K, 1 bar). T-HCP revealed high CO₂/N₂ selectivity (up to 63) as well as promising CO₂/CH₄ (up to 9.1) selectivity suggesting its potential applicability for CO₂ separation from flue and natural gases.     

Processing and properties of Nextel™ 720 fiber reinforced alumina-zirconia ceramic matrix composites

The continuous Nextel? 720 fiber-reinforced zirconia/alumina ceramic matrix composites (CMCs) were prepared by slurry infiltration process and precursor infiltration pyrolysis (PIP) process. The introduction of submicron zirconia powders into the aqueous slurry was optimized to offer comprehensively good sintering activity, high thermal resistance and good mechanical properties for the CMCs. Meanwhile, the zirconia and alumina preceramic polymers were used to strengthen the porous ceramic matrix through the PIP process. The final CMC sample achieved a high flexural strength of 200 MPa after one infiltration cycle of alumina preceramic polymer and thermal treatment at 1150 °C for 2 h. The flexural strength retention of the improved CMC sample was 104% and 89% respectively after thermal exposure at 1100 °C and 1200 °C for 24 h.     

减水剂类型对赤泥—矿渣基地聚物注浆材料性能的影响及机理研究

针对赤泥等固体废弃物对环境危害性大且利用率低等问题,以碱激发赤泥-矿渣基地聚物注浆材料为 研究对象,研究了不同掺量的聚羧酸(PA)减水剂、醛酮缩合物(AKC)减水剂和萘系(N)减水剂对材料凝结时间、流动 性及强度等的影响,并通过 XRD、傅里叶红外光谱及 SEM 等设备对减水剂的作用机理进行研究。 结果表明:减水剂增 强了材料的流动性但降低了材料的剪切应力;N 和 PA 减水剂能缩短材料的凝结时间,但 AKC 减水剂会延长材料的凝 结时间;N 和 AKC 减水剂能提高材料的强度,但 PA 减水剂会降低材料的强度;N 减水剂对材料的综合性能提升效果 更加明显,其最优掺量为 0. 7%;减水剂对赤泥-矿渣基地聚物性能提升的作用机理主要是促进地聚合物凝胶的形成。 研究成果为拓展赤泥在工程上的使用途径和效率提供了理论指导。     

Thermal properties of hierarchical YSZ and LZO ceramic microspheres with multi-scaled voids investigated by using theoretical,experimental and simulation methods

Heat transfer within ceramic feedstock powders is still unclear, which impedes optimization of the thermal and mechanical properties of the thermal sprayed coatings. The microspheres (yttria-stabilized zirconia YSZ and lanthanum zirconate LZO) were prepared via the electro-spraying assisted phase inversion method (ESP). The thermal properties of the two ESP microspheres and a commercial hollow spherical powder (HOSP) were investigated by using theoretical, experimental, and simulation methods. Thermal conductivity of the single microsphere was estimated via a novel nest model that was derived from the Maxwell-Eucken 1 and the EMT model. Thermal conductivity of a single YSZ/LZO-ESP microsphere prepared at 1100–1200 °C was within 0.36–0.75 W/m K, which was ～ 20 % lower than that of a single YSZ-HOSP microsphere with a similar porosity. Heat flux simulation showed that high tortuosity around the multi-scaled voids of the ESP microsphere led to a more efficient decrease in thermal conductivity compared with total porosity.     

Adenine-functionalized conjugated polymer as an efficient photocatalyst for hydrogen evolution from water

Conjugated polymers have emerged as a promising class of organic photocatalysts for photocatalytic hydrogen evolution from water splitting due to their adjustable chemical structures and electronic properties. However, developing highly efficient organic polymer photocatalysts with high photocatalytic activity for hydrogen evolution remains a significant challenge. Herein, we present an efficient approach to enhance the photocatalytic performance of linear conjugated polymers by modifying the surface chemistry via introducing a hydrophilic adenine group into the side chain. The adenine unit with five nitrogen atoms could enhance the interaction between the surface of polymer photocatalyst and water molecules through the formation of hydrogen bonding, which improves the hydrophilicity and dispersity of the resulting polymer photocatalyst in the photocatalytic reaction solution. In addition, the strong electron-donating ability of adenine group with plentiful nitrogen atoms could promote the separation of light-induced electrons and holes. As a result, the adenine-functionalized conjugated polymer PF6A-DBTO2 shows a high photocatalytic activity with a hydrogen evolution rate (HER) of 25.21 mmol g^?1 h^?1 under UV-Vis light irradiation, which is much higher than that of its counterpart polymer PF6-DBTO2 without the adenine group (6.53 mmol g^?1 h^?1). More importantly, PF6A-DBTO2 without addition of a Pt co-catalyst also exhibits an impressive HER of 21.93 mmol g^?1 h^?1 under visible light (λ > 420 nm). This work highlights that it is an efficient strategy to improve the photocatalytic activity of conjugated polymer photocatalysts by the modification of surface chemistry.     

Configurational Isomers Induced Significant Difference in All-Polymer Solar Cells

The design of polymer acceptors plays an essential role in the performance of all-polymer solar cells. Recently, the strategy of polymerized small molecules has achieved great success, but most polymers are synthesized from the mixed monomers, which seriously affects batch-to-batch reproducibility. Here, a method to separate γ-Br-IC or δ-Br-IC in gram scale and apply the strategy of monomer configurational control in which two isomeric polymeric acceptors (PBTIC-γ-2F2T and PBTIC-δ-2F2T) are produced is reported. As a comparison, PBTIC-m-2F2T from the mixed monomers is also synthesized. The γ-position based polymer (PBTIC-γ-2F2T) shows good solubility and achieves the best power conversion efficiency of 14.34% with a high open-circuit voltage of 0.95 V when blended with PM6, which is among the highest values recorded to date, while the δ-position based isomer (PBTIC-δ-2F2T) is insoluble and cannot be processed after parallel polymerization. The mixed-isomers based polymer, PBTIC-m-2F2T, shows better processing capability but has a low efficiency of 3.26%. Further investigation shows that precise control of configuration helps to improve the regularity of the polymer chain and reduce the π–π stacking distance. These results demonstrate that the configurational control affords a promising strategy to achieve high-performance polymer acceptors.     

Stable Light-Emitting Electrochemical Cells Using Hyperbranched Polymer Electrolyte

The choice of an adequate electrolyte is a fundamental aspect in polymer light-emitting electrochemical cells (PLECs) as it provides the in situ electrochemical doping and influences the performance of these devices. In this study, a hyperbranched polymer (Hybrane DEO750 8500) blended with a Li salt is used as a novel electrolyte in state-of-the-art Super Yellow (a polyphenylenevinylene) based LECs. Due to the desirable properties of the hyperbranched polymer and the homogeneous and smooth films that it forms with the emitting polymer, PLEC with excellent electroluminescent properties are obtained using a pulsed current bias scheme. The devices are very stable, with lifetimes in excess of 2000 h with initial luminance values above 450 cd m⁻², a peak efficiency of 12.6 lm W⁻¹, and sub-minute turn-on times. The stability of the devices is also studied by measuring the photoluminescence (PL) of the semiconductor during electroluminescent operation. The findings suggest that it is possible to observe the quenching of the PL in vertically stacked devices due to the advancement of the doped fronts in the film and an immediate PL recovery when the bias is removed.     

KCl/NaCl/CPI复合盐阳离子聚合物钻井液在南海大斜度井段中的应用

为改善南海东部惠州25-8油田大斜度井因泥岩水化造浆而引起的井壁失稳和钻井液增稠影响携砂的问题,在现有成熟PLUS/KCl钻井液的基础上开展复合盐阳离子聚合物钻井液研究,对钻井液配方进行了优化,评价了优化后钻井液的流变性、抑制性、封堵性和润滑性,并在惠州油田进行了现场应用。结果表明,复合盐阳离子聚合物钻井液配方中,无机盐类抑制剂KCl和NaCl的适宜加量为3%和12%、有机阳离子聚合物抑制剂PF-CPI适宜的加量为2.0%。该钻井液抑制性强,防膨率高达93.32%,钻屑回收率87.56%;受到钻屑侵污后的钻井液流变性能波动小,仍具有较低的黏度和合适的切力,有利于大斜度井携砂;封堵性和润滑性均优于PLUS/KCl钻井液体系。现场应用2口井,钻井液流变性良好,平均起下钻速度提高,钻井过程顺利,无复杂情况发生。复合盐阳离子聚合物钻井液可改善南海大斜度井起下钻阻卡的问题。     

High-Performance All-Solid-State Supercapacitor Electrode Materials Using Freestanding Electrospun Carbon Nanofiber Mats of Polyacrylonitrile and Novolac Blends

Herein, this paper reports a facile method to prepare electrospun carbon nanofiber mats (ECNFMs) with high specific surface area and interconnected structure using polyacrylonitrile (PAN) as a precursor and novolac resin (NOC) as a polymer sacrificial pore-making agent. Without additional treatment, the prepared ECNFMs have a highly porous structure because NOC decomposes in a wider temperature range than most polymer activators. The NOC content in the PAN nanofibers shows important effects on porosity. The BET specific surface area of ECNFMs reaches a maximum of 1468 m² g⁻¹ when the precursor nanofibers contained 30 wt% NOC (ECNFM-3) after carbonization at 1000 °C. The supercapacitor device from ECNFM-3 electrode and all-solid-state electrolyte shows excellent cycling durability and high specific capacitance: ≈99.72% capacitance retention after 10 000 charge/discharge cycles and ≈320 mF cm⁻² at 0.25 mA cm⁻². Furthermore, it shows a large energy density of ≈11.1 $\mu$Wh cm⁻² under the power density of 500 mW m⁻². Activation of carbon nanofibers simply by the addition of NOC into precursor nanofibers can offer a handy way to prepare ECNFMs for high-performance all-solid-state supercapacitors and other potential applications.     

Enhancing the Photovoltaic Performance of Ladder-Type Heteroheptacene-based Nonfullerene Acceptors by Incorporating Halogen Atoms on Their Ending Groups

Ending group halogenation is an effective strategy for modulating the energy levels, bandgaps, and intermolecular interactions of nonfullerene acceptors. Understanding the influence of different halogen atoms on the acceptor properties is of great importance for designing high-performance nonfullerene acceptors. Here, three acceptor–donor–acceptor (A-D-A) type nonfullerene acceptors (M5, M6, and M7), which are constructed by using a ladder-type heteroheptacene core without the traditional sp³ carbon-bonded side chains as the electron-rich core, and 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile without or with halogen atoms as the ending groups. The nonfullerene acceptors with chlorinated (M6) and brominated (M7) ending groups exhibit broadened absorption spectra, down-shifted energy levels, and enhanced molecular ordering compared to the counterpart without any halogenated ending groups (M5). Among the nonfullerene acceptors, M6 has the strongest intermolecular π π interaction with its shortest π π interaction distance and the longest coherent length which are beneficial for enhancing the charge transport and therefore boosting the photovoltaic performance. An excellent power conversion efficiency of 15.45% is achieved for the best-performing polymer solar cell based on M6. These results suggest that the halogenated ending groups are essential for high-performance heteroheptacene-based nonfullerene acceptors considering their simultaneous enhancements in both the light-harvesting and the charge transport.