RAFT聚合制备结构明确的荧光标识聚甲基丙烯酸甲酯

以铁氰化钾为氧化剂,通过N-咔唑二硫代甲酸钠的水相氧化制备了高纯度的中间体二硫化双(N-咔唑硫代甲酰)(DTCD),DTCD以晶体的形式从水中析出,提纯简单,性质稳定.通过DTCD与偶氮二异丁腈(AIBN)或偶氮二氰基戊酸(ACVA)的反应合成了2种性能优异的叔丁腈酯基RAFT试剂,N-咔唑二硫代甲酸异丁腈酯(CYCBD)和N-咔唑二硫代甲酸氰基戊酸(CVCBD),新合成工艺的副反应和杂质被大量减少,最终产物的收率可达80%以上.以CYCBD和CVCBD为可逆加成断裂链转移(RAFT)试剂,研究了它们对甲基丙烯酸甲酯(MMA)RAFT聚合的控制能力,结果表明CYCBD和CVCBD是性能优异的RAFT试剂,可以很好地用于制备结构明确、分子量分布窄的链末端咔唑标记的聚甲基丙烯酸甲酯(CPMMA),由它们所制得的CPMMA的PDI小于1.2.研究结果还表明CYCBD和CVCBD及由其合成的CPMMA在四氢呋喃(THF)溶液中具有显著的荧光特性,CPMMA在358nm处有很强的荧光发射峰,而且,在浓度范围为0.1～20μmol/L的THF溶液中,CPMMA的荧光发射强度与其浓度具有良好的线性关系.通过CYCBD和CVCBD可以方便地制备结构明确且具荧光标识的功能聚合物。     

Poly(ethylene glycol)/poly(ethyl cyanoacrylate) amphiphilic triblock copolymer nanoparticles as delivery vehicles for dexamethasone

Amphiphilic triblock copolymers, poly(ethyl cyanoacrylate)‐b‐poly(ethylene glycol)‐b‐poly(ethyl cyanoacrylate) (PECA‐b‐PEG‐b‐PECA), were synthesized via oxyanion‐initiated polymerization with sodium alcoholate‐terminated PEG as macroinitiator. PECA‐b‐PEG‐b‐PECA were characterized by gel permeation chromatography system, ¹H NMR and FTIR. The results indicate that the copolymerization is well controlled with narrow molecular weight distribution. The dexamethasone (DXM)‐loaded PECA‐b‐PEG‐b‐PECA nanoparticles (NPs) were prepared by nanoprecipitation technique and then characterized by Laser Particle Size Analyzer, ¹H NMR and transmission electron microscopy. The drug‐loaded PECA‐b‐PEG‐b‐PECA NPs are of spherical shape with average size of less than 100 nm. The drug‐loaded amount (DLA) and encapsulation efficiency of DLNPs were investigated by HPLC. The results show that DXM can be effectively incorporated into PECA‐b‐PEG‐b‐PECA NPs, which provides an optional delivery system for DXM and other hydrophobic drugs. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7809–7815, 2008     

Stabilized micelles of amphoteric polyurethane formed by thermoresponsive micellization in HCl aqueous solution

The thermoresponsive micellization behavior of amphoteric polyurethane (APU) was studied in HCl aqueous solution (pH 2.0) through light scattering, transmission electron microscopy, and fluorescent measurement. When APU concentration is high enough, nonreversible assembly of macromolecules can be observed with temperature decreasing from 25 to 4 degrees C. However, micelles reaching equilibrium at 4 degrees C can self-assemble reversibly in the temperature range of 4-55 degrees C. According to our research, we found it is the temperature sensitivity of the poly(propylene oxide) (PPO) segments that leads to the reassembly of APU at lower temperature. We proposed that core-shell-corona micelles ultimately form with hydrophobic core, PPO shell, and hydrophilic corona when temperature increases from 4 to 25 degrees C. This structure is very stable and does not change at higher temperatures (25-55 degrees C). That provides a new way to obtain stable micelles with small size and narrow size distribution at higher concentration of APU.     

Structure,electronic, and magnetic properties of 3d transition metal intercalated borophene/BP heterostructures

The intercalation of various atoms or molecules has become one promising way to manipulate the electronic and magnetic properties of layered materials. Using density functional calculations, we explored the 3d transition metal (TM) intercalated α-borophene/black phosphorus (α-B/BP) heterostructure, TM@(α-B/BP) (TM = Sc-Ni), on their structure, electronic and magnetic properties. Our results demonstrate that TM@(α-B/BP)s can be ferromagnetic (FM), antiferromagnetic (AFM) and nonmagnetic depending on the choice of TM atoms, and most systems have large magnetic anisotropic energy. Particularly, Ti@(α-B/BP) is AFM semiconductor with Néel temperature of 470 K, which is much higher than room temperature. Moreover, the electronic and magnetic properties of TM@(α-B/BP)s can be further altered by the TM intercalation concentration. Our results provide a feasible way to design promising candidates for applications in electronic and information storage devices.     

Pd/ZSM-5/MCM-41催化剂加氢脱硫性能研究

本工作将三种材料：全硅MCM-41 （Si-MCM-41）、通过机械混合Si-MCM-41和HZSM-5得到的Z-MCM-41-M、通过在HZSM-5外部包覆Si-MCM-41制备得到的Z-MCM-41,采用XRD、N₂吸附-脱附、NH₃-TPD、Py-IR手段进行了表征.分别以这些材料为载体,制备出负载型贵金属Pd催化剂,以二苯并噻吩（DBT）为模型化合物,在固定床反应器上进行加氢脱硫（HDS）性能考察.反应结果表明,载体的表面积或分散程度并不是影响负载型Pd催化剂HDS性能的关键性因素,催化剂的HDS性能受到载体的孔尺寸和载体的酸性双重影响.负载在酸性载体上表现出较好的HDS性能和加氢选择性,与溢流氢有关.其中,在三种催化剂中,Pd/Z-MCM-41催化剂表现出最高的HDS活性和优异的加氢活性,说明在载体的介孔孔道结构中引入微孔的酸中心对提高加氢脱硫活性有重要影响,仅靠机械混合方式制备的载体不能将介孔的孔道优势与微孔的酸性优势表现出来,不能产生较好的协同催化作用,具有介孔孔道结构和适中酸性的Z-MCM-41复合材料是潜在的贵金属加氢脱硫催化剂载体.     

微通道连续合成UiO-66系列改性MOF材料

采用内交叉指型微反应器连续合成UiO-66材料. 连续微通道法强化了物料之间的混合, 极大提高了生产效率, 晶体产物呈六面体形, 粒径在100 nm以下. 考察了温度、 总进料流量和停留时间等条件对合成过程及产物的影响. 结果表明, 升高温度有助于晶粒的生长; 随着总进料流量增大, 晶体粒径减小; 晶体的形成需要一定的停留时间, 超过该停留时间, 晶体粒径不再增大. 通过优化实验条件, 可以实现系列纳米级UiO-66-X材料(X=NH₂, NO₂, Br)的连续合成.     

神府大柳塔煤结构浅析

用^1H-、^13C-NMR和 FTIR对神府大柳塔2 煤（简称DL2)在420℃和到的甲苯萃取物（产率为25.6W?f)和甲苯＋20％ 四氢萘萃取物（产率为66.6W?f）进行了分析，并据此按Brown-Ladner修正式求取了它们的结构参数。根据萃取物的结构参数和萃 取过程分析 推断了D L2煤 的结构 。认为DL2煤的结构 特点为：结构中含有较大量氢化芳环和 长直链取代基，羟基仅占氧含量的三分之一左右，有少量羰基存在于小分子或支链中。     

粘度法研究壳聚糖与两性聚氨酯胶束间的相互作用

通过粘度法考察了壳聚糖(CS)在盐酸水溶液中与表面带有正电荷的两性聚氨酯(APU)胶束的相互作用，并研究了小分子盐浓度、pH及不同混合方式对复合体系粘度的影响．结果表明：在壳聚糖／APU盐酸混合体系中，较高浓度下APU胶束与壳聚糖分子间的静电斥力作用导致壳聚糖大分子链的伸展，使体系粘度提高，同时降低了壳聚糖溶液对电解质、pH的敏感性；不同混合过程导致壳聚糖大分子构像及其与APU组装、复合形态有很大差别，使混合体系流变性表现出明显的不同．