共查询到20条相似文献,搜索用时 15 毫秒
1.
为了制备电致偏振光发光材料, 以对苯二乙炔和2,5-二溴苯衍生物为单体,通过Sonogashira偶联反应, 采用不同Pd催化剂, 合成了一种侧基横挂偶极基团的液晶聚苯撑乙炔. 单体的化学结构通过IR, NMR和元素分析等方法得到确证. 聚合物外观为黄色粉状固体, 室温下溶于CHCl3和THF等有机溶剂. 将聚合物加热到各自的玻璃化转变温度以上都能形成液晶态并显示双向液晶性. 考察了不同催化剂对合成的聚合物的分子量、聚合物链中单体单元的结构排列以及液晶性质的影响. 结果表明, 两种不同的Pd催化剂对合成的聚合物的分子量以及液晶态温度范围影响不大, 但对聚合物的立构规整性以及聚合物的液晶态织构有较大的影响. Pd(PPh3)4作催化剂合成的聚合物中单体单元的结构排列较单一, 可以观察到清晰的液晶态织构. 以PdCl2(PPh3)2为催化剂合成的聚合物链中单体单元的结构排列相对复杂, 液晶态织构不明显. 变温X 射线衍射研究证实聚合物均为向列相液晶. 相似文献
2.
9,9-Bis(4-aminophenyl)fluorene (APF) polymers were synthesized by two different pathways. The different synthetic routes gave polymers with different structures. FT-IR and NMR studies revealed that the catalytic oxidative polymerisation of APF in acetonitrile produced P2, whereas oxidative polymerisation of APF in aqueous alkaline media gave P3. The effects of these different techniques on spectral, thermal, optical, electrical, electrochemical, and morphological properties of resulting polymers were investigated. 相似文献
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Typical biopolymers exhibit structures and order on different length scales. By contrast, the number of synthetic polymers with a similar degree of hierarchical structure formation is still limited. Starting from recent investigations on the structures of amyloid proteins as well as research activities toward nanoscopic scaffolds from synthetic oligopeptides and their polymer conjugates, a general strategy toward hierarchically structured pi-conjugated polymers can be developed. The approach relies on the supramolecular self-assembly of diacetylene macromonomers based on beta-sheet forming oligopeptides equipped with hydrophobic polymer segments. Polymerization of these macromonomers proceeds under retention of the previously assembled hierarchical structure and yields pi-conjugated polymers with multi-stranded, multiple-helical quaternary structures. 相似文献
4.
Crystalline Hetero‐Stereocomplexed Polycarbonates Produced from Amorphous Opposite Enantiomers Having Different Chemical Structures 下载免费PDF全文
Dr. Ye Liu Meng Wang Wei‐Min Ren Yue‐Chao Xu Prof. Dr. Xiao‐Bing Lu 《Angewandte Chemie (International ed. in English)》2015,54(24):7042-7046
Stereocomplexation is the stereoselective interaction between two opposite enantiomeric polymers through an interlocked orderly assembly. Most studies focus on the stereocomplex formation from the crystalline opposite enantiomers having the identical structure; nevertheless, rare examples were reported regarding the crystalline stereocomplexes from enantiomeric polymers having different chemical structures. Herein we show a strategy for polymer orderly assembly through the formation of crystalline hetero‐stereocomplexed polymeric materials by the cocrystallization of amorphous isotactic polycarbonates with different chemical structures and opposite configurations. The behaviors in the crystalline state are significantly different from that of the component enantiomeric polymers or their homo‐stereocomplexes. This study is expected to open up a new way to prepare various semicrystalline materials having a wide variety of physical properties and degradability. 相似文献
5.
合成了带正电荷密度不同的聚离子亚基化合物,探讨了聚合物结构对外源基因转染真核细胞的影响规律。从实验结果看,聚离子亚基化合物结构影响外源基因转染效率,但其影响程度与靶细胞的种类相关,对HeLa细胞,NIH3T3细胞,聚离子亚基化合物的正电荷密度加大,其促基因转移功能加强;而对PA317包装细胞,结果相反。 相似文献
6.
采用低温溶液聚合方法,以N-(2,5-二羟基苯)亚甲基-4-取代苯胺和不同结构的二酰氯为单体,合成了两类新的高分子.聚合物的液晶行为用DSC、偏光显微镜和X射线衍射进行了表征,发现其中一类为向列型热致液晶高分子,另一类则无液晶性.随单体结构的改变,聚合物的特性粘数、熔点(Tm)和液晶态的清亮点(Ti)均呈现规律性变化。 相似文献
7.
新的含T-型二维液晶基元的液晶高分子的合成 总被引:4,自引:0,他引:4
采用低温溶液聚合方法,以N-(2,5-二羟基苯)亚甲基-4-取代苯胺和不同结构的二酰氯为单体,合成了两类新的高分子。聚合物的液晶行为用DSC、偏光显微镜和X射线衍射进行了表征,发现其中一类为向列型热致液晶高分子,另一类则无液晶性。随单体结构的改变,聚合物的特性粘数、熔点(Tm)和液晶态的清亮点(Ti)均呈现规律性变化。 相似文献
8.
基于氢键作用结合的超分子聚合物 总被引:5,自引:1,他引:4
非共价键结合的超分子聚合物由于其特殊的结构及性能引起了广泛的关注。本文在介绍超分子化学、氢键及超分子聚合物的基础上,主要综述了以氢键为结合力的多重氢键作用、羧基(D)与吡啶基(A)作用以及氢键与其它非共价键协同作用形成的超分子聚合物体系,并对超分子聚合物的研究现状及前景进行了评述。 相似文献
9.
基于氢键作用结合的超分子聚合物 总被引:1,自引:0,他引:1
非共价键结合的超分子聚合物由于其特殊的结构及性能引起了广泛的关注。本文在介绍超分子化学、氢键及超分子聚合物的基础上,主要综述了以氢键为结合力的多重氢键作用、羧基(D)与吡啶基(A)作用以及氢键与其它非共价键协同作用形成的超分子聚合物体系,并对超分子聚合物的研究现状及前景进行了评述。 相似文献
10.
E. G. Bulycheva N. M. Belomoina V. G. Vasiliev I. V. Elmanovich L. A. Wasserman Steve Lien-chung Hsu Po-Yang Cheng 《Doklady Physical Chemistry》2016,471(1):190-193
Sulfonated polyphenylquinoxalines with different content of sulfo groups have been synthesized by polymer analogous reactions under different conditions. The rheological properties of these polymers in Nmethylpyrrolidone have been studied. The mechanical properties of films based on sulfonated polyphenylquinoxalines under uniaxial tension have been measured. The structures of the polymers have been examined by AFM. 相似文献
11.
Monte Carlo calculations of protein binding to affinity ligands tethered to a surface by polymers have been done and analyzed with statistical mechanical perturbation theory. The interaction of the polymers with the surface, the solvent and the protein has been varied. Different solution conditions of the polymers have been investigated, varying from collapsed polymer structures on a surface to structures extending out in the solution (athermic condition) or to mushroom like structures (hydrophobic polymers grafted on hydrophilic surface). The variation in binding of model proteins of different sizes and interactions with polymers has been studied. In general, smaller proteins bind better than larger proteins. Two types of polymer collapses have been studied. One type is due to increased polymer-surface attraction. The second type is due to increased polymer-self attraction. In the former case the binding, as a function of degree of collapse, decreases monotonically except for small proteins with attraction to the polymer. For collapses of the second type the loss of binding goes through a maximum except for large proteins. 相似文献
12.
Prof. Dr. Cosima Stubenrauch Dr. Angelika Menner Prof. Alexander Bismarck Dr. Wiebke Drenckhan 《Angewandte Chemie (International ed. in English)》2018,57(32):10024-10032
Emulsions, foams, and foamed emulsions have been used successfully as templates for the synthesis of macroporous polymers. Based on this knowledge this Minireview presents strategies to use, optimise, and upscale these templating methods to synthesise tailor‐made porous polymers. The uniqueness of such polymers lies in the ability to tailor their structures and, therefore, their properties. However, systematic studies on structure–property relations are lacking mainly because the templating scientific community is “split into two”: the polydisperse and monodisperse camps. Thus, it is time to build a bridge between the camps, that is, to synthesise porous polymers with very different structures from the same precursors to determine the relationship between the structure and the properties. 相似文献
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14.
Polishchuk I. E. Matukhina E. V. Makarova N. N. Timofeeva T. V. 《Russian Chemical Bulletin》2003,52(3):539-544
The idealized liquid-crystal structures of two cyclolinear organosilicon polymers, viz., poly(oxyhexaorganocyclotetrasiloxy-2,6-diyls), where the alkyl substituent is Et (1b) or Pr (1c), were modeled. The columns of monomer units in polymers have different conformations, viz., a distorted long boat in 1b and a distorted long chair in 1c. Both polymers have columnar structures with the most probable antiparallel arrangement of the columns. 相似文献
15.
Meana-Esteban B Lete C Kvarnström C Ivaska A 《The journal of physical chemistry. B》2006,110(46):23343-23350
Polymers from azulene (A) and 2-[(E)-2-azulen-1-ylvinyl]thiophene (B) electrochemically synthesized are materials with a broad absorbance in the UV-vis spectral region. An experimental approach to correlate the Raman and in situ FTIR spectra from azulene based polymers according to the effective conjugation coordinate theory (ECC) is presented. Film characterization was made by Raman and Fourier transform infrared attenuated total reflectance, FTIR-ATR spectroscopy. Throughout the whole work A was used as a model compound. The polymers were synthesized at different polymerization potentials in order to create different structures. Polyazulene showed a divergent Raman response upon change in excitation wavelength, lambda(exc)= 514 nm and lambda(exc)= 780 nm, in comparison to common conducting polymers. The FTIR-ATR measurements were made during charging-discharging of the polymers. The IR spectra of the conducting state show new doping induced infrared active vibrations (IRAV) in the region between 1600 and 700 cm(-1) and a broad electronic absorption in the high energy range (4000-8000 cm(-1)). Two different structures of the polymer from B are formed, and both follow the trends for conducting polymers upon charging. 相似文献
16.
new series of sulfur-contalning side chain liquid crystalline polymers were described. Mesomorphic side chains with methylene spacer in different length have been synthesized and their structures were identified by NMR, IR and MS.The liquid crystalline nature of the polymers was characterlzed by microscopy.The Polymers have liquid crystalline nature. 相似文献
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This review describes the recent advances in the chemistry of titanium-, zirconium-, and hafnium-containing polymers. The paper does not focus on the catalytic role of molecules including metal in their structure, but instead, on the different ways to incorporate these group 4 metals in macromolecular structures. The synthetic approaches of these structures are exposed, according to the three different routes listed, which are the blending, the chemical modification, and the direct polymerization. A particular interest is accorded to the applications of these group 4 metal-containing polymers, which impact various fields such as ceramic, biomedical, and photovoltaic materials. 相似文献
19.
Coimbatore R. Gopalakrishnan Bukkinakere K. Sadashiva 《Macromolecular rapid communications》1998,19(2):97-102
The synthesis and thermal properties of side-chain liquid-crystalline polysiloxanes containing a naphthalene moiety are described. The hydrosilylation of the monomers (ω-alkenenaphthoic acid derivatives) with poly(hydrogenmethylsiloxane) resulted in the desired ferroelectric polymers. Two series of polymers were prepared using two slightly different core unit structures. Preliminary results of optical polarising microscopy and differential scanning calorimetric investigations are reported. The polymers show smectic A and chiral smectic C phases. 相似文献
20.
The results of studying the characteristics of various polymers that possess different structures and are used for various applications after their modification by minor amounts of fullerene C60 are summarized. The character of bonds that arise in fullerene-doped polymer compositions is considered. Mechanical, physicochemical, and physical characteristics of fullerene-containing polymers that show promise for modern technologies are described. The reasons for improving the performance of fullerene-containing polymers are analyzed. 相似文献