聚异戊二烯-丝胶接枝共聚物的合成与性能研究

以异丙苯过氧化氢和四乙烯五胺为氧化还原对引发剂,通过乳液聚合合成了聚异戊二烯接枝丝胶乳液(PL-g-SS),其结构和性能经NMR,TEM及激光粒度分析表征.结果表明:丝胶成功地接枝到聚异戊二烯上;PL-g-SS双亲纳米微球具有明显的PL为核,SS为壳的核壳结构,平均粒径48nm,且粒径分布较为均匀.采用杂凝聚法将PL-...     

环氧化淀粉基核壳纳米粒子增韧聚乳酸的研究

通过酰氯接枝反应在淀粉大分子链上引入长烷基链和碳碳双键,使淀粉具有自乳化性能并增加反应位点,采用无皂乳液聚合将丙烯酸乙酯(EA)与酯化改性淀粉接枝共聚制备以淀粉为核的核壳粒子,即核壳粒子为硬核软壳的结构,通过添加甲基丙烯酸缩水甘油醚(GMA)进一步制备环氧化核壳粒子.将环氧化核壳粒子与聚乳酸(PLA)进行熔融共混改性,...     

温敏性异丙基丙烯酰胺-二氧化硅透明质酸核壳型杂化微凝胶的合成和体积相变行为

通过溶胶-凝胶法,利用硅烷偶联剂(KH550)对纳米SiO2颗粒进行原位改性,使其表面带正电。改性后的SiO2颗粒(MSiO2)通过静电作用吸附带负电的透明质酸(HA)形成核壳颗粒(HA-MSiO2)。进一步在壳层HA链上接枝聚合N-异丙基丙烯酰胺(NIPAM)制得核壳结构温敏性杂化微凝胶(PNIPAM-HA-MSiO2),并用AFM和SEM表征其在云母表面的成膜性能。结果表明:HA-MSiO2核壳颗粒平均粒径约为182 nm,壳层厚度15 nm,其粒径或壳层厚度可以通过改变MSiO2溶液或HA溶液的浓度来调节;温敏性PNIPAM-HA-MSiO2微凝胶的体积相变温度为32°C,与PNIPAM溶液的最低临界溶解温度(LCST)一致,在体积相变温度以下旋涂于云母表面的微凝胶呈现球形颗粒,体积相变温度以上旋涂膜可以转变为致密的膜。     

两亲性纤维素接枝聚脱氢枞酸共聚物的制备及性能研究

通过均相原子转移自由基聚合法(ATRP)将生物质基疏水性松香单体(脱氢枞酸(2-甲基丙烯酰氧基乙基)酯,MAEDA)接枝到纤维素骨架上合成了全生物质基两亲性的纤维素-g-聚脱氢枞酸接枝共聚物(cellulose-g-PMAEDA).ATRP反应过程动力学研究表明cellulose-g-PMAEDA接枝共聚物的合成过程是活性可控的;傅里叶红外光谱(FTIR)、核磁共振氢谱(1H-NMR)、凝胶色谱(GPC)和X射线衍射(XRD)结果证实了cellulose-g-PMAEDA接枝共聚物的成功合成;由于聚脱氢枞酸侧链的引入,cellulose-g-PMAEDA接枝共聚物的热稳定性,疏水性能明显提高,并且具有紫外吸收性能;动态光散射仪和透射电镜结果表明两亲性cellulose-g-PMAEDA接枝共聚物能够在水溶液中自组装成平均粒径约为200 nm左右的纳米微球,并且该纳米微球具有以纤维素为壳,聚脱氢枞酸酯为核的核壳结构.     

含氟两亲接枝共聚物的制备及其与牛血清蛋白作用的研究

用端基反应法合成了对乙烯基苄基的聚乙二醇大分子单体,将该大分子单体与甲基丙烯酸六氟丁酯共聚,合成了一种含氟两亲接枝共聚物.利用1H-NMR1、9F-NMR、GPC对大分子单体和两亲接枝共聚物进行了表征.表面张力法测定了两亲接枝共聚物的临界胶束浓度,发现随着共聚物中含氟链段含量的增加,其临界胶束浓度降低.采用荧光光谱研究了含氟两亲接枝共聚物与牛血清蛋白(BSA)的相互作用,结果表明由于含氟链段疏水力的作用,含氟两亲接枝共聚物能与牛血清蛋白发生相互作用使其荧光增强,随着含氟两亲接枝共聚物浓度和共聚物中含氟链段含量的增加,荧光增强幅度加大.通过透射电子显微镜(TEM)和激光光散射粒度仪(PCS)测试发现,当BSA加入到含氟两亲接枝共聚物的胶束溶液后,所得胶束的粒径和粒径分布变大,共聚物胶束由规整的实心核壳结构变为囊泡状核壳结构.     

无规-类接枝共聚物自组装制备交联纳米微球

无规-类接枝共聚物(SFG)由大分子单体-己内酯改性丙烯酸酯(FA)、亲油性单体苯乙烯和甲基丙烯酸缩水甘油酯(GMA)共聚所得，SFG与聚苯乙烯在甲醇溶液中进行自组装，形成核壳结构纳米胶束，进一步对PGMA壳进行化学交联。最终得到具有核壳结构的纳米微球。动态激光光散射和透射电子显微镜表征结果显示SFG自组装形成了窄分布的纳米微球，微球粒径在100～200nm之间。     

干酪素存在下丙烯酸丁酯的乳液聚合及聚丙烯酸丁酯/干酪素核壳结构乳腔粒的形成

将丙烯酸丁酯(BA)在干酪素(CA)存在下使用异丁基过氧化氢(TBHP)为引发剂,采用无皂乳液聚合方法,通过接枝聚合制备了直径在150 nm左右具有核壳结构PBA/CA纳米复合微粒.探讨了反应温度、引发剂用量、BA和CA质量比等条件对单体转化率、接枝效率和乳胶粒粒径及其分布的影响,确定了制备此类复合乳胶粒的实验条件并对...     

水性聚氨酯及其接枝共聚物分散液颗粒的形态研究

通过自乳化法合成了水性聚氨酯 ,并用甲基丙烯酸甲酯对其进行了接枝共聚 .用动态光散射对其胶束粒径进行了测量 ,并用透射电镜对胶束的粒子形态进行了观察 ,研究结果表明 ,胶束粒子的粒径与聚氨酯结构中的二元醇组成有密切的关系 ,亲水性二元醇合成的聚氨酯胶束粒径比疏水性二元醇合成的要大 ;随聚丙二醇含量增多 ,接枝共聚反应更易进行 ,且接枝后的胶束粒径比接枝前增大 ,但随丙二醇含量增加 ,接枝共聚反应难以进行 ,且胶束粒径接枝前后变化不大 ,并有减小的趋势 ;随聚氨酯分子侧链的柔顺性增加 ,主链的刚性增强 ,胶束粒子易发生微相分离 ,形成壳 核结构     

PMMA/CA核壳纳米微粒的制备与表征

采用乳液聚合方法,不使用任何乳化剂,将甲基丙烯酸甲酯(MMA)在干酪素(CA)存在下使用叔丁基过氧化氢为引发剂,通过接枝聚合制备了直径在150 nm左右的具核壳结构的PMMA/CA纳米复合乳胶粒,乳胶粒的核壳结构通过透射电镜得到了证实.探讨了反应温度、引发剂用量、核壳质量比等条件对单体转化率和接枝效率的影响.阐明了制备...     

光敏性无规-类接枝双亲聚合物的合成与自组装行为的研究

通过ε 己内酯改性丙烯酸酯 (FAn ,n =1～ 4 )与肉桂酰氯反应合成了一系列光敏性大单体 (FAnC ,n =1～ 4 ) ,以FAnC与甲基丙烯酸 (MAA)进行自由基聚合 ,制备具有光敏性的双亲无规 类接枝共聚物 (PMFAnC) .用红外光谱、凝胶渗透色谱、核磁共振和差示扫描量热仪等对共聚产物进行了表征 .双亲性PMFAnC可以在选择性溶剂中进行自组装 ,形成以PMFAnC中PFAnC疏水链段为核 ,PMAA亲水链段为壳的高分子胶束 .核内的肉桂酰基由紫外光引发发生光交联反应 ,得到具有稳定壳 核结构的胶束 .动态激光光散射、透射电子显微镜结果表明 ,PMFAnC在水溶液中形成了一定结构的光敏性纳米胶束 ,在紫外光照射下PMFAnC胶束内核发生光聚合反应使胶束粒径减小     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.