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1.
利用动态力学分析(DMA).透射电子显微镜(TEM)和小角X 光光散射(SAXS)对聚砜(PSF)、聚二甲基硅氧烷(PDMS)和聚对羟基苯乙烯(PHS)三元多嵌段共聚物PSF—PDMS—PHSn的形态结构进行了研究.结果表明,PSF—PDMS—PHSn的形态结构出现了许多新的现象,除具有微相分离的基本特征外,还出现双连续相双分散相的特征.在适当的嵌段长度和组成下,通过TEM观察到一种新的特殊形态 蜂窝状形态结构,并在嵌段共聚物两相界面处直接观察到非常清晰的界面相.同时,对该形态的形成过程作了初步讨论.  相似文献   

2.
研究了几种新型含有机硅二元和三元多嵌段共聚物的氧,氮选择透过性能。其中双酚A聚羟基醚-聚二甲基硅氧烷二元多嵌段共聚物-(PHE-PDMS)的透氧系数P02=510Barrer,氧氮分离系数a02/N2=2.2;聚苯醚-聚二甲基硅氧烷-聚对羟基苯乙烯三元多嵌段共聚物-(PPO-PDMS-PHS)的P02=156Barrer,do2/N2=2.4,两者都具有良好的力学性能,此外,含有机硅三元多嵌段共聚  相似文献   

3.
新型含有机硅二元多嵌段共聚物的研究   总被引:1,自引:0,他引:1  
报道了聚羟基醚(PHE)、聚羟基醚砜(PHES)、酚酞聚羟基醚(PPHE)和聚对羟基苯乙烯(PHS)与端胺基聚二甲基硅氧烷(PDMS)通过羟胺缩合生成ABmn新型结构的可溶性含有机硅二元多嵌段共聚物,m值在1~6之间,详细讨论了反应物浓度对共缩聚反应的影响,并通过分子量测定、红外光谱分析和动态力学分析(DMA)技术初步确定了其反应机理、结构和动态力学性能.  相似文献   

4.
含有机硅三元多嵌段共聚物的研究   总被引:1,自引:0,他引:1  
以双酚A聚砜(PSF)为硬段、聚对羟基苯乙烯(PHS)为半硬段、聚二甲基硅氧烷(PDMS)为软段合成了三元多嵌段共聚物,并对其动态力学和抗张性能比较研究,结果表明该三元多嵌段共聚物为多相结构;在引入半硬段PHS后两相间的界面相增宽,粘接力增大,其强度和模量高且稳定,使含有机硅高分子材料强度低的弱点得以改善,扭(TBA)结果显示,这种三元多嵌段共聚物具有多重转变,且在-20℃至50℃间有两个较大的几  相似文献   

5.
以双酚A聚砜(PSF)为硬段、聚对羟基苯乙烯(PHS)为半硬段、聚二甲基硅氧烷(PDMS)为软段合成了三元多嵌段共聚物,并对其动态力学性能和抗张性能进行了比较详细的研究,结果表明该三元多嵌段共聚物为多相结构;在引入半硬段PHS后两相间的界面相增宽,粘接力增大,其强度和模量高且稳定,使含有机硅高分子材料强度低的弱点得以改善。扭辩分析(TBA)结果显示,这种三元多嵌段共聚物具有多重转变,且在-20℃至50℃间有两个较大的几乎重叠的吸收峰;这表明这种三元多嵌段共聚物的相分离结构较为复杂,并有良好的阻尼性能。  相似文献   

6.
合成了不同软锻段长度和不同链段含量的系列对苯二甲酸乙二酯-环氧乙烷(PET-PEO)多嵌段共聚物,用NMR质子谱测定了硬链段一,对部分溶于氯仿的PET-PEO多嵌段共聚物进行了分离,并分别测定基氯仿可溶物和不溶物的硬边段一、熔融热谱和热结晶谱,揭示了PET-PEO多嵌段共聚物的组成不均一性及其对软段长度和硬链段一的信赖性,进而用DSC热谱证明了软链段和硬链段的结晶能力与PET-PEO多嵌段共聚物组  相似文献   

7.
利用DSC、DMA、TEM和XPS对[PSF-PDMS-PHS]n/PSF共混物的相容性及表面组成进行了研究.结果表明,PDMS在共混物表面的富集与PSF均聚物和[PSF-PDMS-PHS]n中硬段的相容性有关;PDMS在相容的共混物体系表面的富集与对应的多嵌段共聚物组成基本相近;不相容共混物体系表面PDMS的富集程度相对较高,当共混物本体中有机硅含量从1%增至5%,表面层PDMS的含量迅速增加,可达到嵌段共聚物中PDMS的含量.  相似文献   

8.
多嵌段聚氨酯大孔共聚物的制备   总被引:3,自引:0,他引:3  
多嵌段聚酯大孔共聚物经缩聚和加聚反应分步聚合得到,并利用FTIR,DSC,SEM和BET等对其结构、形态结构和孔结构进行了比较详细的研究。结果表明,该聚合物为微相分离且可能存在三种微区结构的多嵌段共聚物,其干态下的比表面积有10-250m^2/g之间,平均孔径在100-350A左右,在聚合温度下,接近于聚氨酯θ条件的溶剂为最佳致孔剂。  相似文献   

9.
RATE-DETERMINING STEP IN OLEFIN HYDROFORMYLATION OVER SUPPORTED AQUEOUS-PHASE CATALYSTSRATE-DETERMININGSTEPINOLEFINHYDROFORMY...  相似文献   

10.
单茂钛催化剂用于苯乙烯-乙烯嵌段共聚物的合成与表征   总被引:1,自引:0,他引:1  
乙烯(E)与苯乙烯(S)的嵌段共聚合用自制的两种催化剂———茂基三呋喃甲氧基钛[CpTi(OCH2O)3]和茂基三苄氧基钛[CpTi(OCH2Ph)3]进行了研究.考察了促进剂三甲基铝(TMA)及乙烯的预聚合时间对聚合结果的影响,发现不同的催化体系有不同的[TMA]最佳值以及随着乙烯预聚合时间的延长总的催化效率降低.对嵌段共聚合产物用丁酮、四氢呋喃和氯仿连续萃取分离,得到四氢呋喃中的可溶级分即嵌段共聚物PE b sPS,它占总嵌段共聚合产物的40wt%~60wt%.对嵌段共聚物用DSC、WAXD、FTIR和13C NMR等方法进行了表征.  相似文献   

11.
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%.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
Zhanhui Yang  Shiyi Yang  Jiaxi Xu 《Tetrahedron》2017,73(23):3240-3248
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.  相似文献   

15.
16.
《Tetrahedron》2014,70(21):3377-3384
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.  相似文献   

17.
Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.  相似文献   

18.
A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.  相似文献   

19.
A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).  相似文献   

20.
Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO4 oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.  相似文献   

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