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复合微乳液聚合制备P(MMA-UA)纳米乳胶粒子的研究 总被引:14,自引:0,他引:14
将聚氨酯预聚体可聚合乳化剂 (APUA)和甲基丙烯酸甲酯 (MMA)的复合微乳液体系 ,分别用水溶性过硫酸钾 (K2 S2 O8)和油溶性偶氮二异丁腈 (AIBN)作引发剂 ,进行微乳液聚合研究 ,制备了P(MMA UA)复合纳米乳胶粒子 .研究了APUA用量、聚合温度对聚合动力学的影响 ;用透射电子显微镜 (TEM)观察了不同乳化剂浓度及引发剂体系对胶粒形态、大小及分布的影响 .结果表明 ,用可聚合乳化剂APUA可制得稳定性很好的P(MMA UA)纳米级核 壳型乳胶粒子 ,乳胶粒径在 5 0nm左右 .随着乳化剂用量增加 ,粒子变小 ;不同类型的引发剂对胶乳的性质有较大影响 ,以APUA为乳化剂 ,K2 S2 O8为引发剂 ,在聚合反应过程中或在聚合反应后的放置中 ,会出现P(MMA UA)的纳米水凝胶 (Nanogel)现象 . 相似文献
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Chunjun Chen Xupeng Yan Yahui Wu Shoujie Liu Xiaofu Sun Qinggong Zhu Rongjuan Feng Tianbin Wu Qingli Qian Huizhen Liu Lirong Zheng Jing Zhang Buxing Han 《Chemical science》2021,12(16):5938
Oxide-derived copper (OD-Cu) has been discovered to be an effective catalyst for the electroreduction of CO2 to C2+ products. The structure of OD-Cu and its surface species during the reaction process are interesting topics, which have not yet been clearly discussed. Herein, in situ surface-enhanced Raman spectroscopy (SERS), operando X-ray absorption spectroscopy (XAS), and 18O isotope labeling experiments were employed to investigate the surface species and structures of OD-Cu catalysts during CO2 electroreduction. It was found that the OD-Cu catalysts were reduced to metallic Cu(0) in the reaction. CuOx species existed on the catalyst surfaces during the CO2RR, which resulted from the adsorption of preliminary intermediates (such as *CO2 and *OCO−) on Cu instead of on the active sites of the catalyst. It was also found that abundant interfaces can be produced on OD-Cu, which can provide heterogeneous CO adsorption sites (strong binding sites and weak binding sites), leading to outstanding performance for obtaining C2+ products. The Faradaic efficiency (FE) for C2+ products reached as high as 83.8% with a current density of 341.5 mA cm−2 at −0.9 V vs. RHE.CuOx species were shown to exist on OD-Cu during the CO2RR, which resulted from the adsorption of preliminary intermediates (such as *CO2 and *OCO−) on Cu instead of on the active sites of the catalyst. 相似文献
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Ming Duan Gang Wu Tianbin Gu Xiaohui Jiang Lei Zhao Limei Zhou Yunwen Liao Qiang Pu 《Journal of polymer science. Part A, Polymer chemistry》2022,60(9):1468-1479
Present work reports a new type of poly(N-alkyl-2-[4-hydroxybut-2-ynyl] pyridinium bromides) (designated as Po-n, n = 8, 12, 16 of carbon atoms in the alkyl chain). Po-n were synthesized and characterized by FTIR, GPC, and NMR analysis. The possible polymerization mechanism was proposed and supported by theoretic calculation. A preliminary probe was performed on the conductivity and anticorrosive ability of the conjugated polymer. The results showed that these polymers demonstrated poor conductivity, however the conductivity was enhanced by graphene doping. Po-n are good inhibitors for X70 steel corrosion in HCl solution. So, the conjugated polymers may play important roles in the fields of optoelectronic devices and steel corrosion inhibition. 相似文献
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Junyu Dong Tianbin Li Chuan Dai Wen Weng Xinghua Xue Yuyu Zhang Qingle Zeng 《应用有机金属化学》2013,27(6):337-340
A straightforward, protecting‐group‐free protocol for the synthesis of chiral 6‐substituted and 6,6’‐disubstituted binols (binol = 1,1’‐bi‐2‐naphthol) by palladium‐catalyzed hydroxylation, C–N and C–O coupling of chiral 6‐bromo‐ and 6,6’ ‐dibromo‐1,1’‐binaphthols is developed. The protecting group free palladium‐catalyzed hydroxylation, C–O and C–N cross‐coupling protocol affords a straightforward and general method for the synthesis of chiral 6‐substituted and 6,6’‐disubstituted binols with good yields, avoiding the tedious procedures of introduction and removal of protecting groups. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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可吸收引导组织再生膜* 总被引:1,自引:0,他引:1
引导组织再生膜(guided tissue regeneration membrane, GTRM)由于能使组织修复再生能力得到最大程度的发挥而广泛应用于各种软硬组织的修复与再生研究及临床医学中。GTRM分为不可吸收与可吸收GTRM,与不可吸收GTRM相比,由于可吸收GTRM越来越多的优点而备受关注。本文阐述了几种常见的可吸收GTRM材料(以胶原为代表的天然生物材料,以聚酯为代表的合成高分子材料和以羟基磷灰石为代表的可降解无机物材料)及其可吸收GTRM在骨缺损、创伤敷料以及防黏连等领域中的主要应用进展,重点综述了可吸收GTRM的主要制备方法--静电纺丝、溶剂浇铸、相转化及其优缺点。 相似文献
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纳米银(Ag NPs)由于其独特的物理、化学和生物学特性备受研究人员的关注.纳米银应用性能除了受到粒子尺寸、分布、纯度等因素影响,还与纳米银的形状密切相关.纳米银的形状对纳米银的抗菌性能、光学性能以及聚合物纳米银复合材料的综合性能都会产生重要影响.纳米银的形状控制合成可以进一步发挥聚合物纳米银复合材料的性能潜力.因此,不断发展纳米银新的合成方法,研究纳米银形状控制的机理就显得尤为重要.本文综述了纳米银合成方法和不同形状纳米银的最新研究进展,合成方法重点介绍了辐射法、激光烧蚀法、电化学法、光化学法和生物合成法,评述了这些方法的优缺点;同时从模板法、动力学、热力学以及氧化刻蚀4个方面介绍了纳米银形状控制的机理.介绍了聚合物纳米银复合材料的研究进展. 相似文献
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Manli Hua Jinliang Song Xin Huang Honglei Fan Tianbin Wu Qinglei Meng Zhanrong Zhang Buxing Han 《Chemical science》2022,13(18):5196
Selective oxidative cleavage of the C(CO)–C bond in ketones to access esters is a highly attractive strategy for upgrading ketones. However, it remains a great challenge to realize this important transformation over heterogeneous metal-free catalysts. Herein, we designed a series of porous and ultrathin N-doped carbon nanosheets (denoted as CN-X, where X represents the pyrolysis temperature) as heterogeneous metal-free catalysts. It was observed that the fabricated CN-800 could efficiently catalyze the oxidative cleavage of the C(CO)–C bond in various ketones to generate the corresponding methyl esters at 130 °C without using any additional base. Detailed investigations revealed that the higher content and electron density of the graphitic-N species contributed to the excellent performance of CN-800. Besides, the high surface area, affording active sites that are more easily accessed, could also enhance the catalytic activity. Notably, the catalysts have great potential for practical applications because of some obvious advantages, such as low cost, neutral reaction conditions, heterogeneous nature, high efficiency, and broad ketone scope. To the best of our knowledge, this is the first work on efficient synthesis of methyl esters via oxidative esterification of ketones over heterogeneous metal-free catalysts.Ultrathin and metal-free N-doped carbon nanosheets showed high activity and selectivity for oxidative esterification of ketones via C(CO)–C bond cleavage to access methyl esters. 相似文献