CF-2沸石的表面酸性及催化性能

CF-2是一种新型的高硅沸石。1981年我们实验室首先在二乙醇胺-甘油-Na₂O-SiO₂-Al₂O₃-H₂O体系中制备成功^[1],以后才见到关于Theta-1^[2],ISI-1^[3],KZ-2^[4],NO-10^[5]和ZSM-22^[6]沸石的报道。     

二苯并噻吩及其氧化物与离子液体相互作用的理论研究

采用密度泛函理论方法比较了DBT/DBTO₂和[BMIM]⁺[PF₆]^-/[BMIM]⁺[BF₄]^-的相互作用。对最稳定的[BMIM]⁺[PF₆]^-、[BMIM]⁺[PF₆]^--DBT、[BMIM]⁺[PF₆]^--DBTO₂、[BMIM]⁺[BF₄]^-、[BMIM]⁺[BF₄]^--DBT、[BMIM]⁺[BF₄]^--DBTO₂进行了NBO和AIM分析。结果表明,DBT和[BMIM]⁺[PF₆]^-/[BMIM]⁺[BF₄]^-中的咪唑环彼此相互平行,NBO和AIM分析表明它们之间发生了π-π相互作用。H1'和H9'形成的F…H氢键有利于π-π堆积作用的形成。DBTO₂倾向于趋近C2-H2和甲基基团形成O…H相互作用;DBTO₂优先吸附在[BMIM]⁺[PF₆]^-/[BMIM]⁺[BF₄]^-。在模拟油中,[BMIM]⁺[PF₆]^-和[BMIM]⁺[BF₄]^-离子液体对DBTO₂的萃取能力大于DBT,其原因是可能是DBTO₂具有较大的极性和O…H与F…H的氢键作用。     

1,2-双(2,4,6-三溴-3-甲基苯氧基)乙烷的合成

卤代二苯氧基烷烃是一类广泛应用的阻燃剂,其通式如下: 迄今已见诸文献的除m不同的品种外,已有20种以上^[1],其中应用最广泛并已工业化生产的是1,2-双(2,4,6-三溴苯氧基)乙烷^[2].     

一种带有芳基双亲双官能度引发剂的合成

双亲聚合物已广泛地应用于许多领域^[1],但其制备困难^[2~4].     

Ag和Pd及其离子对TiO2光催化分解CH3CHO的影响

当用能量大于其禁带宽度的光照射通有氧气的TiO₂悬浮液时,在TiO₂微粒表面会产生反应活性很高的空穴和O₂^-、H₂O₂等多种活性氧.在上一篇文章中^[1]我们已报道了在通氧气和紫外光照的条件下,向TiO₂悬浮液中加入少量Ag⁺或Pd²⁺,将会大幅度提高体系中H₂O₂的生成量.另外,蔡汝雄等人也曾通过向TiO₂悬浮液中加入SOD的方法来提高其中H₂O₂的生成量^[2],而且证明了H₂O₂生成量的增多有助于杀死子宫癌细胞^[3].另一方面,利用TiO₂光催化来分解处理工业废水中的有机物已多见报道^[4～7].因此,为考察H₂O₂含量的增加是否有助于TiO₂催化分解有机物,我们以CH₃CHO为氧化对象,测定了经Ag和Pd表面修饰以及直接向悬浮体系添加Ag⁺或Pd²⁺离子前后,TiO₂光催化氧化分解CH₃CHO效率的变化,并对氮气和氧气气氛的实验结果进行了测定和比较.     

质子化甜菜碱阳离子与双三氟甲磺酰亚胺阴离子相互作用的理论研究

利用密度泛函理论(DFT)方法, 在B3LYP/6-311＋G(d,p)水平下, 对质子化甜菜碱阳离子与双三氟甲磺酰亚胺阴离子形成的气态阴阳离子对([Hbet][Tf₂N])进行理论研究, 通过几何结构优化和频率分析得到势能面上的六个稳定构型. 计算结果表明[Hbet]^＋和[Tf₂N]^－之间能够形成较强的氢键相互作用, 氢键相互作用的稳定化能主要来源于[Tf₂N]^－中O, N原子的孤对电子和[Hbet]^＋中参与形成氢键的O-H, C-H反键轨道之间的相互作用. 自然布局分析(NPA)给出气态[Hbet][Tf₂N]离子对中阴阳离子间的电荷转移比传统离子液体中电荷转移的数值小. AIM (atoms in molecules)分析得到[Hbet]^＋和[Tf₂N]^－之间的氢键相互作用以静电作用为主. 通过实验和理论结果相比较, 初步探讨影响离子液体熔点及其对金属离子选择性溶解的结构因素.     

植物生物分子的电分析化学研究Ⅷ.秋水仙碱的微分脉冲极谱行为及分析应用

秋水仙碱是近年来新发现的有前途的抗癌植物有效成分。秋水仙碱的测定方法,如容量滴定法^[1]、电位滴定法^[2]、紫外分光光度法^[3]、荧光分析法^[4]和高效液相色谱法^[5]等,手续均不太简便。电化学分析研究秋水仙碱主要有阳极伏安法^[6]和交流极谱法^[7],前者因使用固态电极,重现性较差。后者用非水溶剂作介质,灵敏度不高。     

新奇二茂铁甲基氮C60衍生物的合成、结构

尽管目前人们对富勒烯[C₆₀]的过渡金属有机物研究较多^[1],但通过氮卡宾方式连接的C₆₀二茂铁衍生物尚未见报道。鉴于对C₆₀反应的浓厚兴趣及二茂铁的广泛应用价值^[2]我们 利用C₆₀的缺电子性^[3]将其与二茂铁甲基氮卡宾进行[1+2]环加成反应,分离并表征了一种具有齿轮式结构的新奇C₆₀二茂铁衍生物(CpFeC₅H₄CH₂N)5C₆₀(l)。     

静电纺丝法制备NiO纳米纤维及其表征

纳米级NiO因具有优良的催化和热敏等性能而被广泛用于催化剂^[1]、电池电极^[2,3]、光电转化材料^[4～6]、电化学电容器^[7～8]等诸多方面.迄今,已成功地制备出N iO的纳米颗粒^[9]、纳米线^[10]及纳米薄膜^[11],但是对于具有准一维结构的NiO纳米纤维的制备及性能研究尚未见报道.     

四(4-重氮基苯基)卟啉的合成及其与聚苯乙烯磺酸钠自组装的研究

卟啉是一类重要的功能性小分子染料,近年来,在光化学治疗^[1,2]、光电转换^[3,4]、传感元件^[5]、烯烃环氧化催化剂^[6]和光敏化剂^[7]等方面的研究与应用引起了人们的广泛注意.通过两亲卟啉分子衍生物,或带有负电荷的卟啉衍生物,特别是带磺酸基的卟啉分子与正离子聚电解质自组装,制备带有卟啉结构单元的LB膜和自组装膜已有很多报道^[8～14].     

新引发体系引发MMA活性自由基聚合

近年来 ,关于活性自由基聚合的研究极为活跃 ,已经发现了多种基于增长链自由基被可逆钝化形成休眠种的活性自由基聚合方法[1,2 ] .它们主要包括引发转移终止剂 ( Iniferter) ,稳定自由基聚合( SFRP) ,原子转移自由基聚合 ( ATRP) ,可逆加成 -断链链转移聚合 ( RAFT)等 .其中 ATRP因其具有可聚合单体多 ,反应条件相对缓和等优点而成为该领域的研究热点 [3～ 5] .ATRP活性自由基聚合的实现主要是在过渡金属催化剂的作用下 ,通过循环往复的碳 -卤键的活化、加成、碳 -卤键的再形成而得到最终活性的聚合物 ,引发体系由引发剂、过渡金属…     

甲基丙烯酸缩水甘油酯与甲基丙烯酸氯乙酯共聚反应竞聚率的研究

本文合成了甲基丙烯酸缩水甘油酯、甲基丙烯酸氯乙酯和甲基丙烯酸缩水甘油酯与甲基丙烯酸氯乙酯共聚物。用~1H-NMR谱仪测定了共聚物中两种单体的含量。用Fineman-Ross和Kelen-Tilds两种作图方法以及最小二乘法对单体的竞聚率进行估假。结果表明了甲基丙烯酸氯乙酯的竞聚率(r_1)和甲基丙烯酸缩水甘油酯的竞聚率(r_2)分别为r_1=0.712,r_2=1.081。     

甲基丙烯酸(2-烷基-2-金刚烷)酯的合成及水解研究

甲基丙烯酸(2-甲基-2-金刚烷)酯和甲基丙烯酸(2-乙基-2-金刚烷)酯是两个重要的193nm光刻胶主体树脂的单体.两个化合物是由2-金刚酮与碘甲烷、碘乙烷的格氏试剂反应得到2-甲基-2-金刚醇、2-乙基-2-金刚醇,然后在氢化钠的作用下与甲基丙烯酰氯发生酯化反应制得.酯化产率50%—60%.产品结构经¹HNMR、IR、MS和元素分析表征.在对甲基苯磺酸-水合物的催化作用下对两个单体进行了水解测试,探讨了水解机理,计算出水解速率常数k,k值分别为-1.52和-3.90.     

耐热性星形甲基丙烯酸甲酯共聚物的合成

195 6年 ,Swarzc等 [1,2 ] 报道了一种没有链转移和链终止的阴离子聚合技术 ,提出了“活性”聚合的概念 . 1 995年王锦山等 [3]发现和提出原子转移自由基聚合 ( ATRP)以来 ,活性自由基聚合就成了高分子合成领域的研究热点 ,并合成出各类指定结构的聚合物 [4～ 12 ] .具有环状结构的 N -环己基马来酰亚胺 ( NCMI)被广泛地用于与甲基丙烯酸甲酯 ( MMA)自由基共聚合制备耐热性有机透明材料 [13,14 ] ,但NCMI的引入将降低聚合物的加工流动性 ,若能利用多官能团引发剂如四溴甲基苯实现含 NCMI单体结构的可控 ATRP共聚合 ,合成出星形耐…     

Reversible Addition Fragmentation Chain Transfer Polymerization of Isobutyl Methacrylate

Abstract

The reversible addition fragmentation chain transfer (RAFT) bulk polymerization of isobutyl methacrylate (i‐BMA) has been studied using 2‐cyanoprop‐2‐yl dithionaphthalate (CPDN) as RAFT agent in the presence of 2,2′‐azobisisobutyronitrile (AIBN). The results of polymerizations of i‐BMA show that i‐BMA can polymerize in a controlled way by RAFT polymerization using CPDN as RAFT agent; i.e., the polymerization rate is first order with respect to monomer concentration, molecular weight increases linearly with monomer conversion, and polydispersities are relatively low (PDI?<?1.2). The structure of the polymer was characterized by ¹H‐NMR. A chain‐extension experiment of the resulting polymer was successfully carried out. The influences of [i‐BMA]₀/[CPDN]₀/[AIBN]₀ molar ratio and reaction temperature were investigated.     

Ambient Temperature Photocopolymerization of Tetrahydrofurfuryl Methacrylate and Isobornyl Methacrylate: Reactivity Ratios and Thermal Studies

Photocopolymerization of heterocyclic monomer namely, tetrahydrofurfuryl methacrylate with bulky bicyclic monomer, isobornyl methacrylate with different feed ratios was carried out in bulk with low concentration of an α-hydroxyl ketone based photoinitiator. The ambient temperature photocopolymerization was carried out by using a UV-Visible lamp with fixed low intensity of 0.4 mW cm^?2 for a period of 6 min. The residual monomer remained in the polymerization process were determined by using gas chromatography. The reactivity ratio values for the two monomers were calculated from the copolymer composition data by using Fineman-Ross, Kelen-Tudos, Extended Kelen-Tudos and Mao-Huglin methods. Individually, as well as the average of all the methods revealed that the monomer reactivity ratios of tetrahydrofurfuryl methacrylate were higher than isobornyl methacrylate. The dyad sequence distribution and dyad sequence lengths were calculated using the Igarashi and Pyun method and the sequence length distribution for tetrahydrofurfuryl methacrylate was observed to be higher with an increase in its feed content. This supports the reactivity ratio studies that a higher monomer reactivity ratio value for tetrahydrofurfuryl methacrylate was observed as compared to its comonomer. The thermal studies showed that the glass transition temperatures of the copolymers increased with an increase in isobornyl methacrylate content.     

甲基丙烯酸甲酯自由基聚合反应的统计理论研究

在自由基聚合反应中,每个聚合物分子都是经历成百上千次加成聚合形成。由于聚合次数不完全相同造成实际链长的不等性,故由稳态近似法所获得的结果只是一个平均的概念,对反应未达平衡态时不适用。本文运用统计的方法,克服了非稳态方法的限制。通过从任意时间微元扩展至反应结束,获得了甲基丙烯酸甲酯聚合反应相应的统计关系式,如聚合物的数量、重量分布及聚合物的平均分子量等,对深入了解高分子化学反应的本质具有重要的价值和意义。     

Effect of LiClO4 Salt on Dielectric Properties of Acrylonitrile-Methyl Methacrylate and Acrylonitrile-Isobutyl Methacrylate Copolymers

Poly(acrylonitrile-co-isobutyl methacrylate), PAN-co-PIBMA, and poly(acrylonitrile-co-methyl methacrylate), PAN-co-MMA copolymers are synthesized by emulsion polymerization. The structural characterization is done by FTIR and ¹H-NMR spectroscopy and thermal analyses are performed by thermogravimetric analysis (TGA). After various amounts of LiClO₄ salt loading into copolymer films, the dielectric properties of these films at different temperatures and frequencies are determined. The effects of different methacrylate groups and salt content on the dielectric properties of copolymers are investigated. It is found that the dielectric constant increases systematically with increasing MMA and IBMA content in the copolymer. The samples with higher salt content show higher ac-conductivities.     

Vinyl Polymerization. 254.∗ Polymerization of Methyl Methacrylate by the System Cellulose-Water-Carbon Tetrachloride

Radical polymerization of methyl methacrylate initiated by the system cellulose-water-carbon tetrachloride was kinetically studied. Results obtained are: 1) The amounts of water, carbon tetrachloride, and cellulose affected the conversion. Michaelis-Menten's equation was applied to the relationship between the rate of polymerization and the amount of MMA. 2) Other methacrylates and acrylates were also polymerized by this system. 3) When methanol or ethanol was used instead of water, some weak polymerization activity was observed. 4) Initiating ability depended on the kind of cellulose used. 5) The activity of cellulose was not changed by washing with boiling water or by solvent extraction. 6) Polymerization was inhibited by the presence of air. 7) Heating in the presence of water and carbon tetrachloride markedly decreased the activity of the cellulose.     

Phenylalanine-Tethered pH-Responsive Poly(2-Hydroxyethyl Methacrylate)

A series of pH-responsive random copolymers comprised of 2-hydroxyethyl methacrylate (HEMA) and tert-butyl carbamate (Boc)-protected phenylalanine methacryloyloxyethyl ester (Boc-Phe-EMA) were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization in N,N′-dimethylformamide (DMF) at 70 °C. The synthesized copolymers were comprehensively characterized using a combination of techniques, including ¹H NMR, FT-IR spectroscopy and size exclusion chromatography (SEC). Reactivity of each monomers towards controlled radical polymerization was evaluated by determining the reactivity ratios by virtue of extended Kelen-Tüdös method at high conversions revealed the higher reactivity of non-modified HEMA (r_HEMA=1.03) in contrast to Boc-Phe-EMA (r_Boc-Phe-EMA=0.48). Furthermore, the expulsion of the Boc-groups resulted copolymers with ionizable pendant primary ammonium and hydroxyl groups. To understand the glass transition behaviours of homo- and co-polymers, differential scanning calorimetric (DSC) measurements were carried out. The effect of HEMA content on the pH-sensitivity of the copolymers in aqueous medium was investigated through turbidity measurements. Finally, the counteranion exchange from trifluoroacetate to chloride provided copolymers with enhanced water solubility and unaltered phase transition pH.