Synthesis and characterization of amphiphilc block copolymer poly(methyl acrylic acid)-block-polytetrahydrofuran

Under the specially designated condition the polymerization of both tetrahydrofuran (THF) and tert-butyl methacrylate (tBMA) is a living one. The diblock copolymer, poly(tert-butyl methacrylate)-block-polytetrahydrofuran (PtBMA-b-PTHF), was successfully synthesized by means of the coupling reaction of living cationic PTHF+, SbF6- with living anionic PtBMA-, Li+. LiCl, which has a beneficial effect on the molecular weight distribution (MWD) in the anionic polymerization of (meth)acrylates, hinders the coupling reaction of living chains and cannot be used in the preparation of tBMA precursor. The hydrolysis of the aforementioned diblock copolymer under acid condition results in the amphiphilic diblock copolymer, i.e. poly(methyl acrylic acid)-block-polytetra- hydrofuran (PMAA-b-PTHF). The diblock copolymers were characterized with GPC and IR.     

苯乙烯-丁二烯-甲基丙烯酸甲酯三嵌段共聚物的阴离子聚合及其表征

以正丁基锂为引发剂, 1 ,1-二苯基乙烯为戴帽剂, 2-(2-甲氧基乙氧基)乙氧基锂为络合剂, 在环己烷、四氢呋喃混合溶剂中, 采用阴离子聚合法, 于－70℃～－40℃合成了非极性-极性的三嵌段共聚物聚苯乙烯-聚丁二烯-聚甲基丙烯酸甲酯(S-B-MMA) ,并借用GPC、¹H-NMR、DSC、TEM、IR等仪器对共聚物进行了表征。结果表明, 所得产物具备较窄的分子量分布 (Mw/Mn<1.3) 及微观相分离结构。     

Synthesis and micellization behavior of stimuli-responsive polypeptide hybrid triblock copolymer

Polypeptide hybrid triblock copolymer, poly（L-glutamic acid）-b-poly（propylene oxide）-b-poly （L-glutamic acid） （PLGA-b-PPO-b-PLGA）, was synthesized by the ring-opening polymerization of benzyI-L- glutamic N-carboxyanhydride （BLG-NCA） using poly（propylene glycol） bis（2-aminopropyl ether） as initiator, followed by the subsequent deprotection step. The obtained double hydrophilic triblock co- polymer exhibits ＂schizophrenic＂ micellization behavior in aqueous solution upon dually playing with solution pH and temperature. The multi-responsive micellization behavior of this polypeptide hybrid triblock copolymer has been thoroughly investigated by 1H NMR, laser light scattering （LLS）, tempera- ture-dependent optical transmittance, and circular dichroism spectroscopy （CD）.     

模拟微重力大鼠T淋巴细胞发育异常的初步研究

对模拟空间微重力条件下大鼠T细胞发育受阻的神经免疫调节机理进行初步探究.采用流式细胞检测技术测定模拟微重力大鼠胸腺中不同发育阶段T淋巴细胞的数量变化,用ELISA法测定胸腺组织中去甲肾上腺素(NE)和内源性糖皮质激素(GC)的含量.结果表明模拟微重力模型大鼠出现明显胸腺萎缩(p<0.05),CD3⁺CD4⁺CD8^-和CD3⁺CD4^-CD8⁺T细胞数量明显减少(p<0.05);模拟微重力大鼠胸腺中NE和GC含量有升高的趋势.模拟微重力大鼠胸腺中发生了从双阳性T细胞向单阳性T细胞的发育阻滞,这种异常可能与神经内分泌免疫调控相关.     

求解对流扩散方程的一类AGE方法

结合Crank-Nicolson格式和第二类Saul’yev非对称格式,设计求解对流扩散方程的交替分组显式方法.得到求解对流扩散方程的交替分组显式方法为该方法是绝对稳定的,且使用方便,适合并行计算,具有较好的精度.     

催化合成聚降冰片烯-聚(乙烯-co-丙烯)嵌段共聚物

将活性开环易位聚合得到的聚降冰片烯所带的茂钛取代环丁烷末端基转变成烷氧基茂钛,然后在ＡｌＥｔＣｌ２助催剂存在下催化乙烯与丙烯配位共聚合,合成出聚降冰片烯聚（乙烯ｃｏ丙烯）两嵌段共聚物．考察了铝钛比、聚合温度和单体配比对乙丙共聚合的影响,并通过溶剂萃取及１３ＣＮＭＲ分析对聚合产物进行表征．结果表明约３６％的活性聚降冰片烯有效地转换并在助催剂ＡｌＥｔＣｌ２存在下使乙丙共聚合形成嵌段共聚物．低的聚合温度和铝钛比以及高的乙烯单体比有利于增加乙丙共聚物中形成嵌段共聚物比例     

St/MMA嵌段共聚反应及制备纳米微孔薄膜

采用阴离子聚合技术合成了苯乙烯(St)和甲基丙烯酸甲酯(MMA)的两嵌段共聚物P(St-b-MMA),探讨了环己烷／四氢呋喃混合溶剂对聚合的影响,采用FTIR、^13C NMR等表征产物结构及成分,并以P(St-b-MMA)(聚甲基丙烯酸甲酯链段质量分数为0．31)制备了具有纳米孔洞的高分子薄膜。     

极性单体结构对其阴离子聚合及聚合物性质的影响

在相同条件下,对分子量相同、分子结构不同的α-甲基丙烯酸酯、2-丁烯酸酯两类、4种单体的阴离子聚合进行了探讨。与2-丁烯酸酯相比,α-甲基丙烯酸酯的阴离子聚合易于控制,引发效率高、所得聚合物分子量分布窄。同类单体中,酯基的立体阻碍作用越大,其聚合结果越好。2-丁烯酸异丁酯虽比α-甲基丙烯酸酯难以聚合,但其聚合物却具有作为透明材料的优良性能。尽管α-甲基丙烯酸特丁酯和2-丁烯酸特丁酯的酯基相同,它们的聚合物的热分解性质却有较大差异。     

Synthesis and characterization of triblock copolymer by combining enzymatic condensation polymerization and ATRP

In recent years, enzymatic polymerization[1―3] has been evaluated as methodology for polymer synthesis. In contrast to chemical organometallic catalyst, enzyme is of major interest owing to the special properties, such as high efficiency, high (enantio-,…     

β-丙烯酰氧基丙酸甲氧基乙酯乳液共聚合

对β-丙烯酰氧基丙酸甲氧基乙酯(自制)与丙烯酸乙酯、丙烯酸丁酯以及甲基丙烯酸缩水甘油酯的乳液共聚合反应,考察了乳化剂的种类及用量对聚合反应的影响;不同硫化点单体对其转化率和凝胶含量以及分子量的影响及不同加料方式和反应时间对转化率和凝胶含量的影响.结果表明,选择阴离子型与非离子型复合体系作为聚合反应的乳化体系较为适宜,且采用氧化-还原体系(过硫酸铵和亚硫酸氢钠)较好;选择甲基丙烯酸缩水甘油酯可以得到高转化率、低凝胶含量的橡胶;采用滴加乳液法时聚合速度容易控制;IR、DSC对共聚物的分析表明该共聚产物可用来制备超耐寒丙烯酸酯橡胶.     

Nanoengineered polypeptides from tetraphenylethylene-functionalized N-carboxyanhydride: Synthesis,self-assembly and intrinsic aggregation-induced emission

Ring-opening polymerization of N-carboxyanhydrides (NCAs) bearing pendant groups creates functional polypeptides. In this paper, we report the design, synthesis and polymerization of tetraphenylethylene (TPE)-modified NCA, which is used to incorporate aggregation-induced emission (AIE)-active segments into polypeptides. Specifically, we attempted the synthesis of amphiphilic methoxy poly(ethyleneglycol)-block-poly(γ-benzyl-_l-glutamate)-block-poly(γ-4-(1,2,2-triphenylvinyl)benzyl-_l-glutamate) (PEG-PBLG-PTPELG), which had well-controlled molecular weight and narrow polydispersity. The hydrophilic PEG and hydrophobic PBLG-PTPELG assembled into micelles in aqueous solution with diameter around 70 ​nm, displaying AIE at 480 ​nm. Our work demonstrates that the TPE-modified NCA is applicable for the preparation of the AIE-active polypeptides, integrating the AIE luminogens into the polypeptides which may offer unique opportunities for tuning AIE properties by adjusting the composition and conformation of polypeptides. We preliminarily explored the use of the amphiphilic polypeptides for the formulation of doxorubicin-containing micelles that can potentially be used for real-time monitoring of the nanomedicine distribution.     

Synthesis, structure and ethylene polymerization behavior of titanium complexes [C3H6（N = CH-Ar-O）2]TiCl2

Early transition metal catalysts containing twophenoxy-imine ligands, called FI catalysts which havevery high potential to become a new generation of olefinpolymerization catalysts, are new-type catalysts whichhave attracted much attention in recent years[1—3]. Many ofthem display activities comparable to those of the metal-locene catalysts and, in some cases, behave as living po-lymerization catalysts of α-olefins. Brookhart and Gibsonet al.[4,5] recently reported separately series of Schi…     

Remote sensing of algal blooms using a turbidity-free function for near-infrared and red signals

HARMFUL ALGAL BLOOM ACTS UPON IMPORTANT ENVIRON-MENTAL PROBLEMS IN COASTAL WATERS.A UNIFIED AND IM-PLEMENTING METHOD FOR SURVEY AND MONITORING ALGALBLOOMS HAS BEEN DEVELOPED SINCE LAST DECADE.HOWEVER THERE IS A DATA GAP OF ABOUT TENS YEARS IN THE PERIOD W…     

聚乙烯醇-b-聚苯乙烯嵌段星形聚合物的制备

通过CCl₄调聚反应制备出了末端带有氯原子的聚醋酸乙烯酯(PVAc),进一步引发苯乙烯原子转移自由基聚合得到聚醋酸乙烯酯-b-聚苯乙烯嵌段共聚物(PVAc-b-PSt),此嵌段共聚物与偶联剂二乙烯基苯反应后醇解,得到了聚乙烯醇-b-聚苯乙烯星形嵌段共聚物(PVA-b-PSt)_n。分别以GPC,¹H-NMR及FT-IR对各步反应产物进行了表征,聚醋酸乙烯酯比较完全地引发苯乙烯进行原子转移自由基聚合(ATRP),聚合物相对分子质量与单体转化率呈线性关系,证明聚合过程为活性聚合;以二乙烯基苯偶联PVAc-b-PSt,得到了星形共聚物,并出现了星形共聚物之间的偶合;醇解过程进行比较完全,¹H-NMR及FT-IR谱图表明酯基团已较完全地转变成羟基。     

Well-defined bis（phenolate） lanthanide methoxides as efficient initiators for the polymerization of cyclic carbonate and lactide

Lanthanide methoxides supported by carbon-bridged bis(phenolate) ligands 2,2′-methylene-bis(6-tert- butyl-4-methylphenoxo) (MBMP2-) [(MBMP)Ln( μ-OMe)(THF)2]2 (Ln = Nd (1), Yb (2)) were synthesized in high yields by the protolysis reaction using (C5H5)3Ln(THF) as starting materials, and complex 1 was structurally characterized. The coordination geometry around the center metal can be best described as a distorted octahedron. Complexes 1 and 2 were shown to be efficient initiators for the ring-opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC) and L-lactide. The mechanism of DTC polymerization was explored by the end group analysis of the oligomer.     

一类2n次Kolmogorov系统的极限环

研究一类2n次Kolmogorov系统{dx/dt=x(a0-a1x a3x3-a4x4 a5xy2n-1),dy/dt=y(b1x2n-b2),极限环的存在性问题.主要讨论a5＞0和a5＜0两种情形.当a5＞0时,系统在第一象限内不存在极限环;当a5＜0时,得到了平衡点的稳定性态,系统无闭轨的充分条件以及在第一象限内存在稳定极限环的条件.     

二维1:-5 Lotka-Volterra复四次系统的可线性化条件

本文考虑了如下的一类平面四次复Lotka-Volterra系统的可线性化问题ẋ=x（1-a₃₀x³-a₂₁x²y-a₁₂xy²-a₀₃y³）,ẏ=-y（5-b₃₀x³-b₂₁x²y-b₁₂xy²-b₀₃y³）.该系统为四次齐次多项式扰动下的具有$1:-5$线性项的复Lotka-Volterra系统,给出了该系统可线性化的充分必要条件.     

固定化污泥与固定化小球藻共培养去除污水氮磷研究

为减少污水处理装置排出水中氮元素(N)、磷元素(P)的含量,减轻收纳土地和水体的污染,降低水华暴发的频率,本研究采用海藻酸钠分别固定小球藻和活性污泥,并以不同比例组合成共培养体系,处理经Up-flow Anaerobic Sludge Bed/Blanket(USAB)工艺处理后的真实畜禽养殖废水,同时对比传统悬浮细胞方法对N、P的去除效果。结果表明,在72 h内,较低固定化污泥/固定化小球藻初始比例(R=1/3)下的共培养体系对N、P有较好的去除效率;48 h时NH_~+4-N去除率为83.2%,PO_4~(3-)-P去除率为95.1%;3个半连续批次处理中,NH_~+4-N和PO_4~(3-)-P的去除率保持相对稳定。以上结果说明藻类能促进N、P元素的去除,固定化工艺可提升去除效率,具有应用于畜禽养殖废水处理的潜力。     

Construction and characterization of partiallyntrC-deleted mutants inAlcaligenes faecalis

To study the effect of ntrC gene product on the expression and regulation of other important nitrogen-fixing genes in Alcaligenes faecalis, partially ntrC-deleted mutants of A. faecalis have been generated. To start with, the ntrC gene of A. faecalis was cloned into a suicide plasmid pSUP202 to create a recombinant plasmid pSUM1. The ntrC gene in pSUM1 was then replaced by a lacZ-Km^r fragment resulted in the generation of a plasmid pSUM2. The lacZ fragment in pSUM2 was further removed and a plasmid pSUM3 produced. As a second step, the plasmid pSUM2 or pSUM3 was introduced into the wild type of A. faecalis A1501 by conjugation and two partially ntrC-deleted mutants A15CM1 (ntrC∷lacZ) and A15CM2 (ntrC ^- ) were obtained. To understand the regulatory effect of the NtrC on the expression of nifH and nifA, a nifH-lacZ gene or a nifH-lacZ gene was introduced into the ntrC^- mutant by conjugation. The results indicated that: (ⅰ) although the ntrC^-mutant was nif ⁺ , its nitrogen fixation activity was only 20% that of the wild type; (ⅱ) the ntrC^- mutant failed to grow on the medium containing nitrate as a sole nitrogen source; (ⅲ) the regulation of ntrC gene expression did not require its own product; (ⅳ) the expression of nifH in A . faecalis was positively regulated by the ntrC. Deletion of the ntrC resulted in the reduction of nifH expression or even totally inactivated nitrogen fixation; (ⅴ) there was no obvious influence on the expression of nifA in A. faecalis if the ntrC gene was deleted.     

A new drug carrier: Magnetite nanoparticles coated with amphiphilic block copolymer

This paper reports on the synthesis and characterization of 4 nm magnetite nanoparticles coated with amphiphilic block copolymers of poly(ethyl methacrylate)-b-poly(2-hydroxyethyl methacrylate) (PEMA- b-PHEMA) by surface-initiated atom transfer radical polymerization (ATRP), which can act as new po-tential carriers for hydrophobic targeted drug delivery. Vibrating sample magnetometer analysis indi-cated that the magnetite nanoparticles were superparamagnetic at room temperature. Thermogravim-etric analysis (TGA) was applied to studying the property of surface of magnetite nanoparticles, and the surface density of macromolecules was calculated. The grafting density of oleic acid, BrMPA and PEMA was 5.8, 3.9, 0.16 chain/nm2 respectively, which indicates that the initiation efficiency decreases due to the influence of large space of oleic acid molecules. In vitro progesterone and (-)-isoproterenol hy-drochloride release in phosphate buffered saline (PBS) at pH 7.0 and 37℃ was conducted in order to demonstrate the function of drug loading and release. The results showed that the amount of drug carried into the core-shell Fe₃O₄@PEMA-b-PHEMA depends on the length of hydrophobic segment of block copolymer. The release of progesterone (37% after 22 h in our previous work) was compared with the release of (-)-isoproterenol hydrochloride (80% after 50 min), demonstrating that the strong hy-drophobic interaction between hydrophobic segment and drug can effectively control the release of hydrophobic drugs.