4,4′-二氨基二苯甲烷四缩水甘油基环氧与4,4′-二氨基二苯甲烷固化反应研究

本文报道了利用差示扫描量热仪(DSC)跟踪4,4’-二氨基二苯甲烷四缩水甘油基环氧树脂(TGDDM)与4,4’-二氨基二苯甲烷(DDM)固化体系的固化反应研究的结果。在DDM含量低于等当量时,首次在TGDDM-DDM体系的DSC固化曲线上观察到了双重固化反应放热峰。动力学分析结果表明低温固化反应的活化能约56kJ/mol,而高温固化反应的活化能为136kJ/mol。低温固化反应是DDM中伯胺基和仲胺基与环氧基的反应,而高温固化反应是在TGDDM中叔胺基催化下羟基与环氧基的反应。由于这两类反应对交联网密度均有贡献,因此,完全固化TGDDM-DDM树脂的破璃化转变温度T_g受DDM含量的影响较小。     

二胺基二苯基砜／环氧树脂固化动力学研究

研究了二胺基二苯基砜/双酚A环氧树脂体系预凝胶阶段的反应动力学。采用官能团滴定法测定了不同反应条件下的动力学数据,经计算机处理后,发现该体系在预凝胶阶段的反应符合二级反应模型,求出了伯、仲胺基与环氧基反应的活化能分别为60.73 kJ/mol和66.17kJ/mol。依此,本文对该体系的反应机理及芳香二胺中的取代效应问题作了一些探讨。     

红外光谱法实时跟踪支化聚乙烯亚胺/甲基丙烯酸缩水甘油酯的官能团反应EI北大核心CSCD

支化聚乙烯亚胺（PEI）与甲基丙烯酸缩水甘油酯（GMA）反应体系中,PEI的伯胺基可与GMA上的环氧基和双键发生竞争反应,两者的反应速率显著不同。以红外光谱中的GMA羰基吸收峰为基准,分别对GMA中的环氧基和双键的相对含量随反应时间的变化进行半定量研究,确定PEI中伯胺基与GMA中环氧基的反应活性远大于与双键的反应,在5 ℃～40 ℃温度区间内,温度升高会加速两组官能团之间的反应但更有利于环氧基与胺基的反应。这些结果证明,可以利用红外光谱这一简便的方法来半定量地跟踪反应过程并获得最优化的反应条件。     

胺基端基树状分子在铜纳米粒子形成过程中的模板及稳定化作用

通过Micheal加成和胺解的交替反应,制得末端基为氨基的聚酰胺-胺型树状分子（PAMAM）;研究了第7代PAMAM（G7-NH2）在制备铜纳米粒子过程中的模板作用,通过紫外光谱和透射电镜表征了铜粒子的形成过程以及所得铜粒子的大小。结果表明,铜离子不仅与G7-NH2内部叔胺基形成络合物,还与树状分子外部的伯胺基形成络合物;在得到铜粒子的过程中,G7-NH2具有内模板和外模板作用,铜纳米粒子的尺寸随着铜离子与G7-NH2浓度比例的提高而增大;同时,由于铜纳米粒子为G7-NH2模板所包裹,使其在水中具有良好的分散均匀性和稳定性。但在有氧条件下,铜粒子很容易被氧化为G7-NH2（Cu^2＋）n络合离子。     

双马来酰亚胺与4,4'-二氨基二苯醚预聚反应的产物分析

芳香胺改性双马来酰亚胺是双马来酰亚胺最主要的改性方法。本文通过凝胶渗透色谱、酸碱滴定、高效液相色谱等方法分析双马来酰亚胺(BDM)与4,4'-二氨基二苯醚预聚(DDE)的反应物组成,推断产物结构式。结果表明,该条件下的BDM与DDE预聚反应,DDE绝大部分参加反应,BDM则显著剩余。产物中的伯胺主要来自DDE一端的伯胺与双马来酰亚胺的双键加成而另外一端没有加成的生成物。     

含叔胺基的聚醚的开发和聚氨酯离聚物的合成工艺

以甲胺,正丁胺,无水派嗪和Ｎ－甲基二乙醇胺为起始剂,在氢氧化钾催化下,与环氧乙烷聚合得到一系列动能型含叔胺基聚醚,并用端基滴定法与蒸气压渗 透法进行了结构表征。以胺基聚醚为软段,ＭＤＩ和ＢＤ为硬段,在辛酸亚锡催化下,用“一步法”可获得胺基聚醚聚氨酯。适当离子化后,即可得欠段型聚氨,酯离聚物。     

SEBS熔融接枝MAH的接枝机理

通过原位FT-IR跟踪SEBS熔融接枝MAH的反应过程研究SEBS熔融接枝MAH接枝机理。研究结果表明,从原位FT-IR上相应官能团的吸收强度随反应时间变化规律可以看出。不同的引发剂引发SEBS熔融接枝MAH的接枝机理不一样。对引发剂A,MAH在SEBS分子链上的最易接枝位置是在-EB-段的叔碳原子,其次是仲碳原子;对引发剂B,在温度低于180℃之前,仲碳原子最易发生接枝反应,其次是叔碳原子。当温度高于180℃后,伯碳原子、仲碳原子和叔碳原子的反应速率差不多。     

利用膨胀单体合成带有官能团的低聚物

利用膨胀单体的开环聚合反应，在聚合物主链上引入酯基、碳酸酯基、硫酯基、酰胺基等功能基，在适当条件下水解后，可以得到末端带有羧基、经基、硫醇基、胺基等官能团的低聚物。     

永停滴定仪检定方法的研究

永停滴定仪广泛应用于药品生产企业和药品检验机构的容量分析,在容量分析中用以确定滴定终点的仪器,主要用于药品检验重氮化法的滴定终点指示。永停滴定仪在药品检验中大量使用,其量值准确与否直接影响芳香伯胺类药物检测质量的水平。但是,我国目前还没有统一的永停滴定仪检定规程和国家标准及行业标准,无法进行周期检定。本文根据作者长期以来对理化仪器检定工作的经验,探索出一套检定方法以供广大计量检定人员参考。     

水性涂料用聚合物的合成及其在水中的物理形态

水性涂料用聚合物的合成及其在水中的物理形态１．增溶基在水性介质中使用聚合物的重要条件是，聚合物中存在能赋予原本不溶于水的聚合物以水溶性或水分散性的极性官能基（增溶基）。主要的极性官能基是羧酸基、磺酸基和叔胺基。这些官能基在聚合物中的浓度（密度）是决定...     

Potentiometric response characteristics of polycation-sensitive membrane electrodes toward poly(amidoamine) and poly(propylenimine) dendrimers

The potentiometric response characteristics of polycation-sensitive membrane electrodes toward two classes of polycationic dendrimers are examined. Using appropriately formulated polymer membrane electrodes composed of a dinonylnaphthalenesulfonate (DNNS) salt in a plasticized polyurethane matrix, it is shown that poly(amidoamine) (PAMAM) and poly(propylenimine) (PPI) dendrimers are readily detected at submicrogram per milliliter levels via a nonequilibrium response mechanism. The relationship between the total EMF response (at equilibrium) and the specific dendrimer structure is also examined. For both the PAMAM and PPI species, it is shown that the total EMF response does not change significantly with dendrimer generation number; however, the nonequilibrium analytically useful response curves are shifted to higher mass concentrations as the generation number is increased. The relative contributions of the terminal primary amines and the interior tertiary amines of the dendrimers to the observed EMF response are investigated by synthesis of various dendrimer derivatives (acetylated, quaternized, etc.). By comparing the total EMF responses for these derivatives as a function of sample pH, it is demonstrated that the lipophilic cation exchanger (DNNS) within the membrane phase can likely interact electrostatically with both protonated forms of the terminal primary amines and interior tertiary amines of the dendrimer structures. The practical application of the nonequilibrium potentiometric detection of dendrimers for monitoring their interaction with DNA is also demonstrated.     

Thermospectrophotometric analysis of alkylamines utilizing ion association with tetrabromophenolphthalein ethyl ester

Primary, secondary, and tertiary alkylamines react with tetrabromophenolphthalein ethyl ester dye (HTBPE) to form reddish charge transfer (CT) complexes in 1,2-dichloroethane (1,2-DCE). Absorption maxima of the complexes with primary amines occur at ～560 nm, with secondary amines at ～570 nm and tertiary ones at ～580 nm. CT complex formation constants between amines and HTBPE in 1,2-DCE at 25 °C increase in the order of primary, secondary, and tertiary amines but decrease with an increase in temperature. This phenomenon (thermochromism), which depends on the basicity of amines, was thermodynamically studied and used for the selective analysis of alkylamines. For example, tri-n-butylamine could be determined without interference from n-butylamine.     

Tailoring Enzyme‐Like Activities of Gold Nanoclusters by Polymeric Tertiary Amines for Protecting Neurons Against Oxidative Stress

The cytotoxicity of nanozymes has drawn much attention recently because their peroxidase‐like activity can decompose hydrogen peroxide (H₂O₂) to produce highly toxic hydroxyl radicals (?OH) under acidic conditions. Although catalytic activities of nanozymes are highly associated with their surface properties, little is known about the mechanism underlying the surface coating‐mediated enzyme‐like activities. Herein, it is reported for the first time that amine‐terminated PAMAM dendrimer‐entrapped gold nanoclusters (AuNCs‐NH₂) unexpectedly lose their peroxidase‐like activity while still retaining their catalase‐like activity in physiological conditions. Surprisingly, the methylated form of AuNCs‐NH₂ (i.e., MAuNCs‐N⁺R₃, where R = H or CH₃) results in a dramatic recovery of the intrinsic peroxidase‐like activity while blocking most primary and tertiary amines (1°‐ and 3°‐amines) of dendrimers to form quaternary ammonium ions (4°‐amines). However, the hidden peroxidase‐like activity is also found in hydroxyl‐terminated dendrimer‐encapsulated AuNCs (AuNCs‐OH, inside backbone with 3°‐amines), indicating that 3°‐amines are dominant in mediating the peroxidase‐like activity. The possible mechanism is further confirmed that the enrichment of polymeric 3°‐amines on the surface of dendrimer‐encapsulated AuNCs provides sufficient suppression of the critical mediator ?OH for the peroxidase‐like activity. Finally, it is demonstrated that AuNCs‐NH₂ with diminished cytotoxicity have great potential for use in primary neuronal protection against oxidative damage.     

十二系列叔胺捕收剂对高岭石的浮选研究

研究4种十二取代叔胺(DRN,DEN,DPN和DBN)对高岭石的浮选行为。发现4种叔胺对高岭石的浮选捕收能力都较好,其中DEN最好,浮选回收率最高可达92%以上。4种叔胺主要依靠静电引力吸附在高岭石表面,在酸性pH范围内,浮选高岭石的回收率较高,随着pH的增大,叔胺的阳离子组分减少,使得浮选回收率下降。Zeta电位研究表明,高岭石在整个pH范围内,表面主要带负电,4种叔胺与高岭石作用后,能显著增加高岭石的Zeta电位。红外光谱研究表面,4种叔胺主要与高岭石表面发生了电性作用的物理吸附。叔胺中N原子上的取代基的给电子效应和空间位阻效应是造成4种叔胺浮选能力差异的主要原因。     

Modifying the adsorption behavior of polyamidoamine dendrimers at silica surfaces investigated by total internal reflection fluorescence correlation spectroscopy

Polyamidoamine (PAMAM) dendrimers were modified and tested for use as solution-phase diffusion probes in silica nanostructures. In order for the successful application of dendrimers as solution-phase probes, their interactions with silica surfaces must be understood and controlled, so that the motion of the probe is not influenced by adsorption. Adsorption/desorption kinetics of PAMAM dendrimers and their diffusion in solution near silica surfaces were investigated with total internal reflection fluorescence correlation spectroscopy (TIR-FCS). Dendrimers of generations 3, 5, and 7 were dye-labeled with carboxyrhodamine 6G. Because PAMAM dendrimers are positively charged in solution (having primary amines as end groups), significant adsorption of these molecules to the negatively charged silica surface was observed. Adsorption/desorption rates and the equilibrium constant for adsorption were determined by fitting the autocorrelation functions to a kinetic model. The desorption rate decreases and the absorption equilibrium constant increases with higher dendrimer generation. To reduce the adsorption of these probes to silica surfaces, the labeled dendrimers were reacted with succinic anhydride, converting the primary amine end groups to negatively charged carboxylic acid groups. These carboxylated dendrimers did not detectably adsorb to silica from aqueous solution. TIR-FCS was used to determine their free-solution diffusion constants near silica surfaces, and the corresponding hydrodynamic radii compare favorably with values reported from forced Rayleigh scattering measurements.     

以酯端基PAMAM树形分子为模板在N，M-二甲基甲酰胺溶剂中制备金纳米粒子

用UV-vis、FT-IR光谱研究了HAuCl4和酯端基聚酰胺胺(PAMAM)树形分子在N，N-二甲基甲酰胺(DMF)溶剂中的相互作用，提出HAuCl4与树形分子之间的络合机理：[AuCl4]^-离子与质子化叔胺基团形成离子对，Au^3 离子与PAMAM树形分子上的酯基和酰胺基团形成配位作用。在DMF溶剂中酯端基PAMAM树形分子与HAuCl4配位后用柠檬酸钠还原形成金纳米粒子，UV-vis光谱和TEM图像分析表明了随树形分子代数的增加，金纳米粒子的直径减小，并提出了树形分子-金纳米复合物的结构模型：(1)较低代数的树形分子环绕在金粒子的外围；(2)在较高代数的树形分子空腔内部封装金纳米粒子。     

聚酰胺胺(PAMAM)树状分子在我国的研究进展

综述了聚酰胺胺(PAMAM)树状分子在我国的研究进展;介绍了聚酰胺胺(PAMAM)树状分子的合成方法:发散法、收敛法、发散收敛结合法,以及聚酰胺胺(PAMAM)树状分子在表面活性剂、催化剂、纳米材料、絮凝剂等应用研究领域所取得的成果;并评述了聚酰胺胺(PAMAM)树状分子在我国发展的方向.     

PAMAM/PA6共混合金的结晶结构与性能

研究了不同代数和不同份量的PAMAM树形分子对PAMAM／PA6共混合金力学性能的影响，并用DSC、WAXD对PAMAM／PA6共混合金的结晶结构进行了分析．结果表明，PAMAM在低用量时，可提高PAMAM／PA6的结晶速度，使微晶尺寸变大，对共混合金起增塑作用；而在高用量时则对PAMAM／PA6的结晶过程起抑制作用，使微晶尺寸变小，对共混合金起增强作用．     

二代PAMAM树型高分子的荧光现象及其荧光标记应用

首次发现不含荧光团的二代poly(amido amine) (PAMAM) 树型高分子的荧光现象,研究结果表明在无荧光基团的PAMAM树型高分子中,胺类官能团是产生荧光的关键.不同酸度条件下,生成荧光中心的速度不同,而且荧光的稳定性也不相同.同时发现当反复变换酸碱性时PAMAM树型高分子的荧光强度逐渐变弱.由于低代PAMAM树型高分子的良好生物相容性和低廉价格,其有可能成为新型生物荧光标记物.     

微细蒙脱石颗粒界面疏水改性机理研究

采用密度泛函理论方法计算了不同甲基取代程度的甲基胺类(伯胺、仲胺、叔胺和季铵)的分子形式和离子形式在蒙脱石(001)表面上的吸附能、吸附平衡构型和差分电子密度,并测试了药剂作用后蒙脱石悬浮液上清液透光率、表面对药剂的吸附量和表面接触角。结果表明:甲基胺类离子形式在蒙脱石表面的吸附能比分子形式的大很多,可以稳定吸附在表面上;烷基胺中N原子上的甲基对H原子的取代程度越高,吸附能越小,对蒙脱石表面的疏水改性能力越差;甲基胺类阳离子主要通过静电作用和氢键作用吸附到蒙脱石表面上;药剂作用后蒙脱石悬浮液的上清液透光率、表面对药剂吸附量和表面接触角的试验结果与模拟结果相一致。