木质素活化改性制备酚醛树脂胶黏剂研究进展

木质素由于化学结构与苯酚相似,通过活化改性可部分替代苯酚制备木质素改性酚醛树脂胶黏剂。既可降低成本、达到生物质资源高效利用的目的,并且制备的木质素改性酚醛树脂胶黏剂有毒残余较低,具有环保意义,是合成制备生物质高分子材料的重要途径。本文综述了国内外研究人员在木质素活化改性制备酚醛树脂胶黏剂研究领域的最新进展,重点介绍了化学改性、物理改性、生物改性等木质素活化改性方法,比较了不同改性产物制备酚醛树脂胶黏剂的性能,并对影响木质素活化改性制备酚醛树脂胶黏剂实现工业化应用的主要因素进行了分析。     

含磺酸甜菜碱两性离子共聚物P(AM-co-VPPS)的合成及盐溶液性质

4-乙烯基吡啶(4-VP)与1,3-丙烷磺内酯在80℃下反应20h,合成了4-乙烯基-1-(3-磺丙基)吡啶内嗡盐(4-VPPS);并在水溶液中与丙烯酰胺(AM)单体进行自由基共聚合,获得了同时含正负离子基团的磺酸甜菜碱两性离子共聚物P((AM-co-VPPS));采用红外光谱和1H-NMR对共聚物结构和组成进行了表征;进而考察了单体组成、引发剂用量、单体总浓度及反应温度对两性离子共聚物特性黏数的影响.通过考察单体投料比与共聚物组成的关系,利用Finemann-Ross和Kelen-Tudos方法,获得AM和4-VPPS单体对的竞聚率分别为2.01、8.71和1.99、8.44.共聚物溶液性质研究结果表明,P(AM-co-VPPS)在含NaCl和CaCl2的水溶液中的特性黏数都比纯水中的大,表现出明显的反聚电解质行为.特性黏数增加的程度随共聚物中4-VPPS单元的含量和水中盐浓度增加而增大;当共聚物中4-VPPS摩尔含量为10.2%时,其在1mol/LNaCl、2mol/LNaCl和2mol/LCaCl2水溶液中特性黏数与在纯水中相比,分别增加47.3%、56.7%和56.8%.     

改性聚合物压裂液的合成及其性能

为了提高油田压裂改造中常用水基压裂液的耐温和耐盐性能,本文以丙烯酸(AA)、丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)和季铵盐型长尾疏水单体(DS)为原料,制备了疏水改性聚合物增稠剂(AAAD)。 有机硼酸盐与葡萄糖酸钠形成配合物(GS-2)为交联剂,再加入其它添加剂,AAAD通过交联反应,制备出改性聚合物压裂液。 评价了该体系的流变性、黏弹性、耐温性、抗盐性和破胶性等性能。 结果表明,压裂液在温度150 ℃、剪切速率170 s^-1条件下具有良好的流变性能;在90 ℃,破胶剂过硫酸铵质量分数为0.01%条件下,4 h即可破胶,破胶液黏度为1.6 mPa·s。     

有机蒙脱土改性脲醛树脂胶黏剂的制备及结构表征

采用"碱-酸-碱"合成工艺,在各阶段将OMMT(有机蒙脱土)投入反应体系,制备有机蒙脱土改性脲醛树脂胶黏剂,测试胶黏剂的各项性能,用XRD(X射线衍射仪)、FTIR(傅里叶变换红外光谱)、SEM(扫描电镜)、TG(热重分析)对改性胶黏剂结构进行表征.实验结果表明,随着OMMT的加入,胶黏剂的游离甲醛含量降低,胶合强度增加.第一阶段投入OMMT,降醛效果明显,第二阶段投入OMMT,补强效果明显.SEM图显示,改性胶黏剂中被剥离成片层状的OMMT因受基体的包覆或挤压,呈现出蜷曲的形状;XRD图谱显示,OMMT/UF胶黏剂的结晶度低于UF胶黏剂的结晶度,有机蒙脱土的加入,破坏了脲醛树脂中羰基和氨基的规整性排列;FTIR图谱表明,改性脲醛树脂胶黏剂中存在大量游离的尿素,胶黏剂的游离甲醛含量低;TG分析得出,改性胶黏剂的TG曲线移向高温方向,材料的热分解温度提高.     

稀土化合物参与的聚丙烯反应挤出接枝马来酸酐

将多种稀土化合物用于等规聚丙烯(iPP)与马来酸酐(MAH)的接枝反应, 对接枝共聚物的结构、 接枝率和加工行为等进行了表征和研究. 结果表明, 稀土氧化物CeO2和Nd2O3的加入促进了iPP熔体接枝MAH的反应, 与未加入稀土化合物的接枝体系相比, MAH单体接枝率最大值分别提高了14%和25%, 同时接枝共聚物的熔体流动速率(MFR)也分别增大了34%和56%. 根据实验条件下接枝共聚物的MFR与MAH单体接枝率间的关系, 并结合熔体接枝反应机理, 提出了采用MFR来表征接枝率的方法, 并建立了工作曲线. 同时, 对不同稀土化合物抑制或促进熔体接枝反应发生的机理进行了初步探讨.     

离子交换与吸附文摘

一种单乙烯的不饱和单体和一种多乙烯的不饱和单体(例如:苯乙烯和二乙烯苯)的共聚反应得到部分交联的共聚物珠体,用MeOCH_2Cl(由HCHO,MeOH和ClSO_3H就地制得到)将共聚物氯甲基化,同时完成交联,并将氯甲基化共聚物胺化,得到了一个比在氯甲基化之前完成交联而制得的类似的离子交换剂具有更为等孔的阴离     

接枝和交联对纳米SiO_2改性NR/PP共混型热塑弹性体的影响

动态硫化制备纳米二氧化硅(SiO2)改性天然橡胶/聚丙烯共混型热塑性弹性体(NR/PP TPE).研究了马来酸酐/苯乙烯/过氧化二异丙苯(MAH/St/DCP)多单体“就地”熔融接枝、交联对TPE力学性能、耐溶剂性能和耐热变形性能的影响,并用SEM分析了TPE的断面形貌.结果表明:纳米SiO2和MAH/St/DCP的最佳质量分数分别为0.03和0.0375/0.0188/0.00375时,MAH/St/DCP接枝、交联改性NR/PP/纳米SiO2TPE的力学性能、耐溶剂性能和耐热变形性能最佳.MAH/St/DCP“就地”接枝、交联通过细化交联NR分散相、改善交联NR分散的均匀性和增加两相之间的共交联,使NR与PP两相界面结合强度明显提高,NR/PP TPE的综合性能得到明显的改善.     

含氟丙烯酸酯共聚乳液及其膜表面特性的研究

以十二烷基硫酸钠 (SDS)和OP 10混合乳化剂 ,制备了甲基丙烯酸全氟辛基乙酯 (FMA8) 甲基丙烯酸丁酯 (BMA) 甲基丙烯酸 (MAA)共聚乳液 .通过DSC、FT IR、1 H NMR对共聚物的结构、组成进行了表征研究 .采用JZHY 180界面张力仪研究了共聚乳液膜表面的性质 ,结果表明 ,随着共聚物中全氟单体含量的增加 ,共聚物膜的表面能显著降低 ,当全氟单体的含量达到 2 5wt %时 ,其表面能降低到 19 74mJ m2 .X ray光电子能谱(XPS)对共聚物表面原子组成的分析结果表明 ,共聚物表面氟的含量远高于其平均含量 ,证明了含氟基团的趋表现象 .经退火处理 ,共聚物膜表面的氟含量增加 ,表面自由能降低     

羟甲基化木质素磺酸盐添加剂对钻井液性能的影响

为了进一步优化木质素磺酸盐作为钻井液处理剂的效能,利用其与甲醛的羟甲基化反应制备了羟甲基化木质素磺酸盐;采用红外光谱仪、X射线粉末衍射仪、扫描电镜等分析了其结构;测定了改性前后的木质素磺酸盐对钻井液流变性、降滤失性、黏土水化膨胀抑制性等性能的影响.结果显示,改性后的羟甲基化木质素磺酸盐的整体结构变化不大,但羟基数量增加,与水的相溶性增强.与木质素磺酸盐相比,羟甲基化木质素磺酸盐在室温下对基浆有较强的提黏作用,经180℃高温老化后降黏、降滤失作用有所增强,形成的泥饼厚度降低,对黏土水化膨胀的抑制作用增强.     

α-甲基苯乙烯-马来酸酐共聚物的合成及其引发的甲基丙烯酸甲酯的无皂乳液聚合

以α-甲基苯乙烯(AMS)、马来酸酐(MANH)为共聚单体,偶氮二异丁腈(AIBN)为引发剂,采用自稳定沉淀聚合法合成了α-甲基苯乙烯和马来酸酐的共聚物,再将其皂化后得到具有引发和乳化双重作用的共聚物.该共聚物可以作为大分子引发剂再引发甲基丙烯酸甲酯(MMA)进行无皂乳液聚合.采用扫描电镜、红外光谱仪、乌氏黏度计等仪器对AMS-MANH共聚物以及乳液聚合产物进行了表征.结果表明,乳液聚合产物是以PMMA为主长链,AMS和MANH低聚物为短链的嵌段共聚物.单体最高转化率可达到85%,特性黏数在80 mL/g左右.乳胶粒子粒径在150～200 nm之间.聚合速率随着引发剂浓度的增加而增大,聚合物的特性黏数随着转化率的提高基本呈线性增大.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.     

Exploring the scope of the Gewald reaction: Expansion to a four-component process

An efficient four-component reaction was developed to take advantage of the reactivity of the 2-aminothiophene-3-carbonitrile functionality, which is obtained during the classical three-component Gewald reaction. Various α-methylene bearing ketones were reacted with malononitrile, elemental sulfur, and aryl/heteroarylnitrile derivatives in t-BuOH/NaOH to afford 2-arylthieno[2,3-d]pyrimidin-4-amines in high yields. Preliminary studies revealed the photophysical properties of the products and their potential for use as metal sensors.