RSC Advances

Wang, Jian; Mei, Quanjing; Lin, Lili; Sun, Fuhua; Li, Jidong; Zou, Qin; Zuo, Yi; Li, Yubao

doi: 10.1039/c8ra09374apmid: 35519981

An obturation biomaterial that possess inherent antibacterial activity has been developed to create a tight seal for the root canal space in treatment. Novel castor oil-based polyurethane sealers composited with different proportions of silver phosphate or zinc oxide nanoparticles were synthesized to investigate the physicochemical properties, antibacterial effect on Enterococcus faecalis, and cytotoxicity on murine fibroblasts compared with commercially available products. The results showed that the physical properties of all of the polyurethane sealers could meet with the standards expected. The microdilatancy character of the polyurethane sealers was particularly preferable for the three dimensional obturation of root canal space. Compared with the silver-loaded polyurethane series, the zinc-loaded polyurethane series showed better antibacterial properties based on the contact mode. Analysis of the kinetics indicated that the setting process of the polyurethane sealers supported a first-order reaction and the setting process was highly effective, with more than 90% of the isocyanate groups participating in the setting reaction within 12 h. This is beneficial for the rapid consumption of monomers, efficiently avoiding inflammation. The in vitro results showed that the polyurethane sealers loaded with zinc oxide nanoparticles or 1 wt% silver phosphate were desirable for cell attachment and proliferation compared with the commercial sealers. In conclusion, the castor oil-based polyurethane-zinc sealers, especially PU-Zn5, present good physicochemical and antibacterial properties and cytocompatibility, and could be a promising candidate for application in the field of root canal treatment.

Liu, Bingxiao; Hu, Guosheng; Zhang, Jingting; Yan, Wen

doi: 10.1039/c8ra10037cpmid: 35519963

Herein, we report novel heat-resistant nylon 10T/66/titania dioxide/glass fibre (nylon 10T/66/TiO2/GF) composites based on as-synthesised nylon 10T/66, which is a copolymer of poly(decamethylene terephthalamide) (nylon 10T). The non-isothermal crystallization behaviors of nylon 10T/66 and nylon 10T/66/TiO2/GF composites were investigated by differential scanning calorimetry (DSC). Jeziorny and Mo equations were used to analyse the crystallization kinetics, whereas the Kissinger method was applied to calculate the activation energy. It turned out that the introduction of TiO2 and GF could accelerate the crystallization of nylon 10T/66 and exhibited an effective heterogeneous nucleation effect. In addition, we conducted yellowing resistance and mechanical property analysis of the nylon 10T/66/TiO2/GF composites. The above results successfully demonstrated that the heat-resistant nylon 10T/66/TiO2/GF composites possess higher crystallization temperature and crystallization rate, whiter color, and better yellowing resistance and mechanical properties than previously as-synthesised nylon 10T/66. Consequently, nylon 10T/66/TiO2/GF composites have great potential to be used as a heat-resistant engineering plastic.

Lin, Bing; Zuo, Yu

doi: 10.1039/c8ra10083gpmid: 35519962

The inhibition effects of five organic carboxylate compounds with different alkylene chain lengths on Q235 steel in a simulated carbonation concrete pore solution (pH 11.5) were studied using quantum chemical calculations, electrochemical measurement and surface analysis. The results show that the adsorption capacity of the inhibitors increases with increasing distance between the CC bond and COO– group. As the alkylene chain length increases, the absolute surface charge value increases and the inhibition effectiveness tends to increase. C11 shows the best inhibition. The carboxylate inhibitors adsorb on a steel surface by forming Fe–OOC–Cx compounds and the CC bonds could enhance the adsorption process.

Wang, Qingbo; Zhang, Junying; Dong, Weimin; Liu, Lintao; Wen, Hang; Yao, Qian; Li, Jing; Wang, Jiyang

doi: 10.1039/c8ra09971epmid: 35519990

TeO–B2O3–BaO glasses with different compositions were prepared by the conventional melt-quenching technique. The spectral properties of Tm3+/Ho3+ co-doped TeO–B2O3–BaO glasses with different doping concentrations were studied. In order to analyze the spectroscopic properties in detail, the Judd–Ofelt intensity parameters, spontaneous radiative probabilities, branching ratios, absorption and emission cross-sections, and gain coefficient spectra were calculated using Judd–Ofelt and McCumber theory based on the absorption and emission spectra. Meanwhile, the optimal doping concentration was determined as Tm2O3: 1.0 mol% and Ho2O3: 1.0 mol%. The results show that Tm3+/Ho3+ co-doped TeO–B2O3–BaO glass is an ideal mid-infrared laser gain medium.

Zhang, Xiaoming; Xia, Zhangxun; Li, Huanqiao; Yu, Shansheng; Wang, Suli; Sun, Gongquan

doi: 10.1039/c9ra00167kpmid: 35519958

Heteroatom doped graphene as a single-atom catalyst for oxygen reduction reaction (ORR) has received extensive attention in recent years. In this paper, the ORR activity of defective graphene anchoring single heteroatom (IIIA, IVA, VA, VIA and VIIA) was systematically investigated using a dispersion-corrected density functional theory method. For all of the 34 catalysts, 14 of which were further analyzed, and the Gibbs free energy of each elementary reaction was calculated. According to the scaling relationship between ΔGOOH* and ΔGOH*, we further analyzed the rate-determining step of the remaining 20 catalysts. The results show that when the ORR reaction proceeds in the path O2 → OOH → O → OH → H2O, the reaction energy barriers are lower than 0.8 eV for Te-SV, Sb-DV, Pb-SV, Pb-DV, As-SV, As-DV, B-SV, Sn-SV and N-SV. Our result provides a theoretical basis for further exploration of carbon-based single-atom catalysts for ORR.

Tsuji, Hideto; Tamura, Ken-ichi; Arakawa, Yuki

doi: 10.1039/c9ra00255cpmid: 35519995

The present paper proposes a versatile strategy for the synthesis and mechanical property manipulation of networked biodegradable polymeric materials composed of well-defined alternating soft and hard domains. As an example of the strategy, we selected biodegradable poly(l-lactide) (PLLA) and poly(ε-caprolactone) (PCL) as the hard and soft components, respectively, and synthesized networked biodegradable polymeric materials composed of well-defined alternating PLLA and PCL domains with different l-lactide (LLA) unit contents via crosslinking of well-defined four-armed diblock copolymers of PLLA and PCL (4-C-L). The strategy reported here, which is also applicable to non-biodegradable polymeric materials, successfully facilitated the synthesis of the networked biodegradable materials composed of alternating hard and soft domains and their mechanical properties of the synthesized materials were largely manipulated by the LLA unit contents of the precursor four-armed diblock 4-C-L copolymers. Moreover, the crystallization behavior and thermal properties of 4-C-L copolymers before and after crosslinking were investigated and discussed.

Nakamura, Tomoya; Ishikura, Yasuhisa; Arakawa, Noriko; Hori, Megumi; Satou, Motoi; Endo, Masaru; Masui, Hisashi; Fuse, Shinichiro; Takahashi, Takashi; Murata, Yasujiro; Murdey, Richard; Wakamiya, Atsushi

doi: 10.1039/c9ra00229dpmid: 35519982

Two p-type semiconducting donor–acceptor polymers were designed and synthesized for use in organic solar cells. The polymers combine a benzodithiophene (BDT) donor and a thiazole-fused benzothiadiazole (TzBT) acceptor. Two TzBT acceptor units are compared, one with an alkylthio group (P1) and the other with a more strongly electron-withdrawing alkylsulfonyl group (P2) at the fused thiazole ring. The strongly electron-accepting nature of the TzBT unit lowers the lowest unoccupied molecular orbital (LUMO) energy of P1 and P2 relative to that of the BT analog (PBDT-BT), without altering the energy of the highest occupied molecular orbital (HOMO). Despite the smaller optical band gaps, bulk heterojunction organic solar cells fabricated using these polymers in a PC71BM blend showed high open-circuit voltages. The power conversion efficiency (PCE) of the P1-based device reached 6.13%. Though efficiency of the P2-based device was lower, photoelectric conversion extended into the near-IR region up to 950 nm.

Wang, Si; Su, Xianli; Bailey, Trevor P.; Hu, Tiezheng; Zhang, Zhengkai; Tan, Gangjian; Yan, Yonggao; Liu, Wei; Uher, Ctirad; Tang, Xinfeng

doi: 10.1039/c9ra00566hpmid: 35519979

Despite the achievable high thermoelectric properties in SnSe single crystals, the poor mechanical properties and the relatively high cost of synthesis restrict the large scale commercial application of SnSe. Herein, we reported that co-doping with Na and Ag effectively improves the thermoelectric properties of polycrystalline SnSe. Temperature-dependent carrier mobility indicates that the grain boundary scattering is the dominant scattering mechanism near room temperature, giving rise to low electrical conductivity for the polycrystalline SnSe in comparison with that of the single crystal. Co-doping with Na and Ag improves the electrical conductivity of polycrystalline SnSe with a maximum value of 90.1 S cm−1 at 323 K in Na0.005Ag0.015Sn0.98Se, and the electrical conductivity of the (Na, Ag) co-doped samples is higher than that of the single doped samples over the whole temperature range (300–773 K). Considering the relatively high Seebeck coefficient of 335 μV K−1 at 673 K and the minimum thermal conductivity of 0.48 W m−1 K−1 at 773 K, Na0.005Ag0.015Sn0.98Se is observed to have the highest PF and ZT among the series of samples, with values of 0.50 mW cm−1 K−2 and 0.81 at 773 K, respectively. Its average PF and ZT are 0.43 mW cm−1 K−2 and 0.37, which is 92% and 68% higher than that of Na0.02Sn0.98Se, 40% and 43% higher than that of Ag0.02Sn0.98Se, and 304% and 277% higher than that of the previously reported SnSe, respectively.

Ma, Weimin; Huang, Jiawei; Li, Chao; Jiang, Yueren; Li, Baolin; Qi, Ting; Zhu, Xiaozhang

doi: 10.1039/c9ra00796bpmid: 35519975

Based on the regioselective intermolecular Suzuki coupling and subsequent intramolecular Ullmann C–O coupling reactions, one-pot synthesis of benzo[4,5]thieno[3,2-b]benzofurans (BTBFs) was developed after optimization of the reaction conditions including catalysts, solvents, bases, ligands and reaction times. The one-pot reaction, with only 2 mol% Pd(PPh3)4 and 2 mol% copper(i) thiophene-2-carboxylate (CuTc) as the catalysts, K3PO4·3H2O as the base and tert-butanol as the solvent, afforded moderate to good yields (up to 70%) for a variety of substrates.

Iacomi, Paul; Lee, U-Hwang; Valekar, Anil H.; Chang, Jong-San; Llewellyn, Philip L.

doi: 10.1039/c9ra00534jpmid: 35519938

Three promising MOF candidates, UiO-66(Zr), MIL-100(Fe) and MIL-127(Fe) are shaped through granulation with a ρ-alumina binder. Subsequently, changes in the surface characteristics and adsorption performance are evaluated through adsorption microcalorimetry at 303 K with several common probes (N2, CO2, CO, CH4, C2H6, C3H8, C3H6 and C4H10), generating a detailed picture of adsorbate–adsorbent interactions. Vapour adsorption experiments with water and methanol were further used to gauge changes in hydrophobicity caused by the addition of the alumina binder. Upon shaping, a decrease in gravimetric capacity and specific surface area is observed, accompanied by an increased capacity on a volumetric basis, attributed to densification induced by the shaping process, as well as a surprising lack of pore environment changes. However, the magnitude of these effects depends on the MOF, suggesting a high dependence on material structure. Out of the three materials, MIL-127(Fe) shows the least changes in adsorption performance and is highlighted as a promising candidate for further study.