核壳乳液聚合法制备含氟硅丙烯酸酯乳液

以氟醇RfCH2CH2OH和乙烯基硅氧烷VTES为原料合成的氟硅单体,与甲基丙烯酸甲酯、丙烯酸丁酯在复合乳化体系中通过核壳乳液聚合制备了稳定的氟硅共聚乳液。对氟硅单体和氟硅丙烯酸酯共聚物的结构用红外光谱进行了表征,结果表明,得到了目标单体和共聚物。共聚物的TEM形态观察发现,乳胶粒子具有明显的核壳结构,平均粒径在125 nm左右。与丙烯酸酯共聚物相比,氟硅丙烯酸酯共聚物乳胶膜的吸水率降低至8.32%,热分解温度提高了23℃,耐溶剂性与氟硅单体的含量关系不大。     

含氟丙烯酸酯共聚物防粘剂的制备及其表面性能研究

以甲基异丁基甲酮为溶剂,偶氮二异丁腈为引发剂,全氟烷基乙基丙烯酸酯、丙烯酸十八酯、丙烯酸丁酯和甲基丙烯酸羟乙酯为原料,溶液聚合制得了均一的含氟丙烯酸酯共聚物防粘剂,并研究了其表面性能。结果表明:全氟烷基乙基丙烯酸酯单体的加入显著降低了共聚物的表面能,提高了共聚物膜的硬度、耐水、耐碱、耐溶剂等性能。当加入ω(氟单体)为30%时,表面能降低至14.7 mN/m,低于有机硅类防粘剂的表面能,含氟丙烯酸酯共聚物膜与压敏胶的的剥离力较低,剩余粘附率为93.2%,该共聚物膜的防粘等综合性能最好。     

水溶性丙烯酸酯共聚物的研究

本文合成了一系列不同结构和组份的丙烯酸酯共聚物,并运用 IR、NMR、MS、热分析等分析测试手段,研究了共聚物的组成和链结构,计算了链结构中甲基、羧基和α-H 的含量;研究了共聚物的结构与性能的关系、羧基含量与水溶性的关系及α-H 与热稳定的关系。地此基础上合成了性能优良的水溶性丙烯酸酯共聚物,为金属表面处理提供一种水溶性封闭漆。     

氟化（甲基）丙烯酸酯聚合物结构与表面润湿性

氟化（甲基）丙烯酸酯聚合物是一类新型的低表面能材料,它的氟化链段使其具有优异的疏水疏油性能,而非氟化（甲基）丙烯酸酯链段则赋予了其良好的溶解性和相容性。通过设计和控制氟化（甲基）丙烯酸酯聚合物的结构可改变聚合物表面润湿性。本文综述了影响氟化（甲基）丙烯酸酯均聚物、无规共聚物、嵌段共聚物、接枝共聚物、核壳共聚物和交联网状共聚物表面润湿性的因素,通过分析聚合物的结晶度、表面元素含量、表面能和接触角讨论了聚合物结构与表面润湿性及润湿稳定性之间的关系,并给出了相关模型,为今后设计合成具有稳定表面润湿性的氟化（甲基）丙烯酸酯聚合物提供了理论依据和指导。     

含疏水链节的聚N-异丙基丙烯酰胺共聚物的温敏性

采用溶液聚合法合成了一系列N-异丙基丙烯酰胺(NIPAM)与甲基丙烯酸甲酯、丙烯酸乙酯、丙烯酸丁酯或甲基丙烯酸丁酯的无规共聚物,用浊度观测法和光散射法测定了不同共聚物水溶液的温敏相转变行为.结果表明:所得共聚物的低临界溶解温度(LCST)均低于均聚物PNIPAM的,酯类单体的结构和含量对共聚物的LCST有显著影响,其中酯基上的烷基对共聚物LCST的影响能力大于丙烯酸酯α位上的烷基,前者对增大共聚物的疏水性有更大贡献.通过NIPAM与特定丙烯酸酯单体进行无规共聚可以合成转变温度低于PNIPAM均聚物且具有预设LCST数值的水溶性温敏聚合物.     

含氟共聚物的制备及其对古砂岩的保护研究

本文选用丙烯酸丁酯(BA)和甲基丙烯酸甲酯(MMA)为非含氟单体,甲基丙烯酸十二氟庚酯(DFHM,C11H8O2F12)为含氟单体,分别获得了含氟丙烯酸酯共聚物乳液(BA/MMA/DFHM)和含氟丙烯酸酯共聚物溶液[P(BA-MMA-co-DFHM)],并分别选用毛细吸收法、喷涂法和刷涂法将其应用于古建筑砂岩的保护研究。结果表明:P(BA-MMA-co-DFHM)溶液因分子量小而容易渗到砂岩内部,在降低砂岩吸水率,提高耐紫外光和耐冻融老化性方面,更能起到良好的保护效果。     

含氟/硅丙烯酸酯乳液的合成进展

含氟丙烯酸酯聚合物具有良好的成膜性、光泽性、柔韧性、耐污性及耐腐蚀性,广泛应用于防腐耐候涂料。但其对基体的附着性差,对颜料、填料的润湿性差,不耐低温,加之含氟丙烯酸酯单体价格昂贵,大量使用受到限制。含氟/硅丙烯酸酯共聚物不仅兼备了含氟聚合物的诸多优良性能,而且能有效地提高与基体的附着力并降低聚合物成本。本文综述了氟/硅改性丙烯酸酯乳液常用单体;核壳型乳胶粒的结构及影响因素;氟/硅丙烯酸酯共聚物合成路线。     

一种光响应性热敏聚合物的合成及性能表征

合成了偶氮单体2-[4-(4′-乙氧基苯基偶氮)苯氧基]乙基丙烯酸酯(EAPEA),利用核磁共振、傅立叶红外和元素分析法对其分子结构进行了表征.利用该单体与异丙基丙烯酰胺共聚得到一种对温度和光敏感的共聚物.共聚物中少量的EAPEA单元能够显著降低聚异丙基丙烯酰胺(PNIPA)的相转变温度.当EAPEA的摩尔含量为2.94%时,相转变温度从PNIPA均聚物的31.8℃下降为22.0℃.在波长为365nm的紫外光照射下,共聚物中的偶氮基团能够从反式构型转变为顺式构型.在紫外光下照30s后,EAPEA摩尔含量为0.98%的聚{异丙基丙烯酰胺-共-2-[4-(4′-乙氧基苯基偶氮)苯氧基]乙基丙烯酸酯}的相转变温度从27.2℃上升到29.3℃.     

一种光响应性热敏聚合物的合成及性能表征

合成了偶氮单体 2 [4 (4′ 乙氧基苯基偶氮 )苯氧基 ]乙基丙烯酸酯 (EAPEA) ,利用核磁共振、傅立叶红外和元素分析法对其分子结构进行了表征 .利用该单体与异丙基丙烯酰胺共聚得到一种对温度和光敏感的共聚物 .共聚物中少量的EAPEA单元能够显著降低聚异丙基丙烯酰胺 (PNIPA)的相转变温度 .当EAPEA的摩尔含量为 2 94%时 ,相转变温度从PNIPA均聚物的 31 8℃下降为 2 2 0℃ .在波长为 36 5nm的紫外光照射下 ,共聚物中的偶氮基团能够从反式构型转变为顺式构型 .在紫外光下照 30s后 ,EAPEA摩尔含量为 0 98%的聚 {异丙基丙烯酰胺 共 2 [4 (4′ 乙氧基苯基偶氮 )苯氧基 ]乙基丙烯酸酯 }的相转变温度从 2 7 2℃上升到2 9 3℃     

含氟丙烯酸酯共聚物的合成与表征

本文以丙烯酸丁酯(BA)和1,1,5-三氢全氟戊基丙烯酸酯 (OFPA)为主要单体,甲基丙烯酸缩水甘油酯(GMA)为活性单体,采用间歇式滴加乳液聚合法合成了含氟丙烯酸酯共聚物.采用红外光谱法和X-射线光电子能谱法对共聚物的结构进行了表征,对共聚物的凝胶含量、耐水、耐溶剂性能以及热性能进行了测试.结果表明共聚物具有良好的耐水和耐溶剂性能,共聚物中保持一定的凝胶率可降低其表面粘性,有利于后期混炼加工;DSC测得的共聚物的玻璃化转变温度可低于-30℃,保持了较好的低温性能.     

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

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.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.