Dec 2006, Volume 1 Issue 4
    

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  • Progresses in organic field-effect transistors and molecular electronics
    Wu Weiping, Xu Wei, Hu Wenping, Liu Yunqi, Zhu Daoben
    2006, 1(4): 357-363. https://doi.org/10.1007/s11458-006-0051-8
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    In the past years, organic semiconductors have been extensively investigated as electronic materials for organic field-effect transistors (OFETs). In this review, we briefly summarize the current status of organic field-effect transistors including materials design, device physics, molecular electronics and the applications of carbon nanotubes in molecular electronics. Future prospects and investigations required to improve the OFET performance are also involved.
  • New approaches to stimuli-responsive polymeric micelles and hollow spheres
    Zhang Youwei, Jiang Ming
    2006, 1(4): 364-368. https://doi.org/10.1007/s11458-006-0049-2
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    This article briefly describes some new approaches to stimuli-sensitive polymeric micelles and hollow spheres, which were developed in the authors  laboratory in recent years. (1) Self-assembly of component polymers to non-covalently connected micelles (NCCM) driven by specific interactions. For example, in water, PCL and PAA formed core-shell nanospheres due to interpolymer hydrogen bonding. After crosslinking the PAA shell and removing PCL core, nanocages  made of PAA network were obtained. This hollow structure shows perfect reversible size-pH dependence. (2) Simultaneous in-situ polymerization of monomers and self-assembly of the polymers. In this approach, PNIPAM network was formed by radical polymerization covering PCL particles. Hollow spheres of PNIPAM network were then obtained by biodegradation of PCL core. Both the core-shell spheres and hollow spheres show reversible size dependence on temperature change because of the phase transition of PNIPAM around 32ºC. (3) Complexation-induced micellization and transition between the micelles and hollow spheres. Graft copolymers hydroxylethyl cellulose (HEC) and PAA were prepared free radical polymerization. The copolymers showed pH dependent micellization, i.e., micelles formed when pH of graft copolymer solution decreased to around 3. The micellar structure could be locked by crosslinking the PAA grafts. The resultant cross-linked micelles undergo pH-dependent transition between the micelles and hollow spheres, which accompanies a remarkable particle size change. Both the micellization and the structure transition were found to be reversible and associated with H-bonding complexation between the main chain and grafts.
  • Synthesis and characterization of rare earth complexes with Phthalaldehyde-lysine Schiff base
    Hu Meixian, Li Ning, Yao Kemin
    2006, 1(4): 369-373. https://doi.org/10.1007/s11458-006-0058-1
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    Ten new rare earth complexes with Schiff base (HL) derived from phthalaldehyde with two CHO groups and lysine, which has unsymmetrical α-and ε- -NH2 groups, were synthesized and characterized by elemental analysis, TG-DTA analysis, UV Vis, IR, and 1H NMR spectra. They were confirmed to be as LnL2(NO3)•4H2O (Ln=La, Pr, Nd, Sm, Y) and LnL2(NO3)•3H2O (Ln=Gd, Tb, Dy, Er, Yb), respectively. Furthermore, their coordination mechanism, spectral properties and probable molecular structures were also discussed.
  • Preparation of lithium fast ionic conductor by sol-gel-hydrothermal method
    Wang Qinghua, Wang Bengen, Xu Yan, Liu Hongyu
    2006, 1(4): 374-377. https://doi.org/10.1007/s11458-006-0047-4
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    The solid fast ionic conductor was synthesized by the sol-gel-hydrothermal method. The influences of dispersion reagent, the alkalinity and the calcination temperature on the surface morphology of nanopowders, the electric conductivity were discussed. When PEG 12000 was used as the dispersion reagent, the alkalinity was 1.0% and the calcination temperature was 550ºC; the electric conductivity at ambience temperature of the inorganic nanopowder of lithium fast ionic conductor synthesized was 2.59 ? 10-3 S•cm-1.
  • Synthesis and characterization of monodisperse CdSe quantum dots different organic solvents
    He Rong, You Xiaogang, Tian Hongye, Gao Feng, Cui Daxiang, Gu Hongchen
    2006, 1(4): 378-383. https://doi.org/10.1007/s11458-006-0052-7
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    Nearly monodisperse CdSe quantum dots (QDs) have been prepared by a soft solution approach using air-stable reagents in different organic solvents. This scheme a supplement to the conventional thermal decomposition organometallic compounds at higher temperatures. CdSe nanocrystals of different sizes could be obtained by simply changing the solvent. This method is reproducible and simple and thus can be readily scaled up for industrial production. The reaction process was monitored by the temporal evolution of the UV-Vis absorption and room temperature photoluminensce spectra. The structures of the CdSe quantum dots were determined by X-ray powder diffraction XRD) and transmission electron microscopy (TEM). The phase-transfer of oleic acid stabilized CdSe nanocrystals into PBS buffer solutions was also studied for their potentials in biological applications.
  • Preparation of anhydrous magnesium chloride in a gas-solid reaction with ammonium carnallite
    Zhou Ningbo, Chen Baizhen, Li Yibing, He Xinkuai
    2006, 1(4): 384-388. https://doi.org/10.1007/s11458-006-0046-5
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    Dehydrated ammonium carnallite was synthesized with bischofite from salt lake and ammonium chloride solution in a 1:1 molar ratio of MgCl2:NH4Cl, dehydrated at 160ºC for about 4 h. The yield was above 85%. The product was then mixed with solid-state ammonium chloride with a 1:4 mass ratio for the further dehydration at 410ºC. The decomposition of NH4Cl made a pressure of NH3 at 30.5 kPa to prevent the hydrolysis of ammonium carnallite. The anhydration of magnesium chloride was achieved at 700ºC. The results showed that anhydrous magnesium chloride contains magnesium oxide in an amount that was less than 0.1% by weight. XRD pattern and SEM micrograph showed a good dispersion of ammonium carnallite and anhydrous magnesium chloride crystals with well-distributed big grains, just enough to meet the need for the production of magnesium metal in the electrolysis process.
  • Preparation and characterization of WO3 from ammonium paratungstate via hydrothermal method
    Li Xiancai, Cao Xiaohua, Wang Wenjuan, Yang Yifeng, Rao Guohua
    2006, 1(4): 389-392. https://doi.org/10.1007/s11458-006-0057-2
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    Tungsten trioxide powder has been prepared from ammonium paratungstate via hydrothermal method using orthogonal and mono-level design of experiments. The effects of preparation process on particle size, specific surface area, crystal form and crystalline morphology of the tungsten trioxide was investigated by TEM and XRD etc. It was found that the optimum conditions of the preparation are hydrothermal crystallization for 8 h at 180ºC, followed by vacuum drying at 45ºC and calcination at 500ºC for 2 h. The blank reference experiment shows that hydrothermal crystallization treatment favors the formation of hexagonal tungsten trioxide, and the tungsten trioxide powder sample prepared by this method has a high degree of crystallinity.
  • Study on preparation of S2O82- /Fe2O3–SiO2 solid acid and its catalytic activity
    Wu Donghui, Jin Ruidi, Wang Xin
    2006, 1(4): 393-397. https://doi.org/10.1007/s11458-006-0064-3
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    The precursors of Fe2O3-SiO2 mixed oxides prepared through co-precipitation method were modified by microwave hydrothermal treatment for the first time. S2O82-/Fe2O3-SiO2 solid acids were formed after being impregnated by (NH4)2S2O8 solution and calcined at high temperature. The samples were characterized by XRD, TEM, N2 adsorption/desorption methods. It was found that the presence of SiO2 obviously retarded the formation and growth of Fe2O3 crystals. Catalyst with appropriate specific surface area and narrow pore size distribution was obtained. The catalytic activities of the solid acids were evaluated by esterification of acetic acid and butanol and the results were compared with those catalysts prepared at normal conditions. The results showed that catalytic activity was extensively improved by microwave hydrothermal treatment.
  • Solid-state synthesis and properties of SmCoO3
    Liu Runru, Xu Dapeng, Li Shuang, Lv Zhe, Xue Yanfeng, Wang Deyong, Su Wenhui
    2006, 1(4): 398-401. https://doi.org/10.1007/s11458-006-0065-2
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    In this paper, perovskite oxide SmCoO3 was prepared by the solid-state reaction method using Co2O3 and Sm2O3 as raw materials. The structure and properties of the samples were investigated by XRD, Raman spectral techniques, and DC measurements and so on. The results of XRD and Raman spectra showed that the mixtures of Co2O3 and Sm2O3 can react to produce a single phase perovskite oxide SmCoO3 around 1353 K. The single-phase SmCoO3 changes from an insulator to a semi-conductor and transition occurs around 470 K. The thermal expansion coefficient (2.17?10-5 K-1) of the single-phase SmCoO3 is approximately equal to that of doped LaGaO3, but much bigger than that of SDC(Ce0.85Sm0.15O2) above 873 K.
  • Studies on photocatalytic activity of Ag/TiO2 films
    Hou Xinggang, Wu Xiaoling, Liu Andong
    2006, 1(4): 402-407. https://doi.org/10.1007/s11458-006-0045-6
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    Ag/TiO2 photocatalytic films were produced by hybrid sol gel method. The photocatalytic degradation of methyl orange (MO) in aqueous solution under 365 nm irradiation on TiO2 and Ag/TiO2 thin films was investigated. The state and amount of Ag species within the film and the enhancement mechanism of photocatalytic activity of Ag/TiO2 were discussed. With a loading molar ratio of Ag/Ti = 0.135 in TiO2 film, the maximum catalytic efficiency was observed.
  • Synthesis of Eu(Ⅲ) and Tb(Ⅲ) complexes with novel pyridine dicarboxylic acid derivatives and their fluorescence properties
    Tang Ruiren, Yan Zi′er, Luo Yiming, Guo Cancheng
    2006, 1(4): 408-413. https://doi.org/10.1007/s11458-006-0056-3
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    Starting from pyridine-2,6-dicarboxylic acid (DPA), a series of novel pyridine-2,6-dicarboxylic acid derivatives were synthesized. In these compounds, 4-(hydroxymethyl) pyridine-2,6-dicarboxylate (4-HMDPA) and 4-[(bis-carboxymethyl-amino)-methyl]-pyridine-2,6-dicarboxylic acid (4-BMDPA) were used as multifunctional ligands to coordinate with Tb(!b) and Eu(!b) and the complexes were prepared. The fluorescence properties of the solid complexes and their solutions were investigated in detail. The results indicated that the weak election-withdrawing group 4-hydroxymethyl in 4-position of pyridine in 4-HMDPA could weaken the fluorescence intensity of the lanthanide complexes. The contradistinctive experimental results showed that the fluorescence intensities of these complexes are related to pH values of the aqueous solutions and the dipole moments of solvent molecules: in the neutral aqueous solutions, the fluorescence intensities of these complexes were strongest, while the dipole moments were lower when the fluorescence intensities were stronger. 4-BMDPA is the better sensitizer and may be used as time-resolved fluoroimmunoassay.
  • Preparation and characterization of silver colloids with different morphologies under ultrasonic field
    Cheng Jingquan, Yao Suwei, Zhang Weiguo, Zou Yi
    2006, 1(4): 418-422. https://doi.org/10.1007/s11458-006-0067-0
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    In the ultrasonic field, stable silver colloids were produced by the reduction of AgNO3 with the protection of PVP using KBH4 or N2H4•H2O as reductant. The main factors affecting the morphology of silver nanoparticles, such as distribution of the ultrasonic field, ultrasonic time, ultrasonic power, and the species of reductant, were studied. The silver colloids were identified by TEM and spectrophotometry. The results indicate that the factors such as distribution of the ultrasonic field, ultrasonic time, ultrasonic power, and the species of reductant have a great impact on the morphology of the silver nanoparticles. The size of the silver nanoparticles decreases with the ultrasonic power and ultrasonic time increasing. Ag nanoparticles prepared in standing wave field preferentially grow in a certain direction, which is propitious for forming hexagonal- and spherical-like silver nanoparticles. Monodispersed spherical silver nanoparticles are easily synthesized in the diffusion field. The stability of silver colloid becomes improved by ultrasonic treatment. For example, precipitate is not found after several weeks for the silver colloid prepared with an ultrasonic treatment time of 180 min. The silver nanoparticles prepared without ultrasonic treatment are large spherical-like and hexagonal. Well-dispersed spherical silver particles with a mean size of about 20 nm have been prepared under ultrasonic treatment. Spherical, spherical-like, and hexagonal silver nanoparticles can be obtained by changing the reductants.
  • Synthesis of fulleropyrrolidine dicarboxylic acid and its scavenging activity to superoxide radicals $(O_2 ^{\bar \cdot } )$
    Liu Xufeng, Liu Xufeng, Chen Zhengxian, Chen Zhengxian, Guan Wenchao, Guan Wenchao
    2006, 1(4): 423-426. https://doi.org/10.1007/s11458-006-0061-6
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    Photochemical reaction of C60 with iminodiacetic ester (NH(CH2COOR)2, R=Me, Et, t-Bu) produced fulleropyrrolidine derivatives fulleropyrrolidine derivatives 2 in a 55%-36% yield (based on consumed C60). The reaction activity correlated with the steric hindrance of R groups. The order of the reaction rates decreased from Me to t-Bu (R=Me>Et>t-Bu). Fulleropyrrolidine derivative 2 (R=Me) were hydrolyzed with NaH and methanol in toluene, and then acidified with HCl to result in the corresponding fulleropyrrolidine dicarboxylic acid 3 in a 65% yield (relative to fulleropyrrolidine derivative 2). C60 derivatives 2 and 3 were structurally characterized by 1H NMR, 13C NMR, IR, and elementary analysis, MS. A chemiluminescence technique was applied to study the effects of their scavenging superoxide radicals (image) generated by pyrogallol autoxidation. The results show fulleropyrrolidine dicarboxylic acid 3 had scavenging activity and the efficiencies were dependent on their concentrations. At the concentration of 3.0×10-4 mol·L-1, fulleropyrrolidine dicarboxylic acid 3 showed a radical scavenging efficiency of approximately 70%. Finally, the influence of structure factor on the scavenging activity was discussed. The results show that the monoadduct of C60, owing to keeping almost intact double bands in C60 moiety, had obvious scavenging activity for superoxide radicals (image).
  • Synthesis of isoxazolidines by 1,3-dipolar cycloaddition and their bioactivity
    Cheng Chunsheng, Li Zhinian, Shu Jinyan, Li Tao, Zhang Baoyan
    2006, 1(4): 427-433. https://doi.org/10.1007/s11458-006-0068-z
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    A series of new isoxazolidines was prepared by 1,3-dipolar cycloaddition of different mono-substituted styrenes with 1,3-dipolar compounds that were prepared by the reaction of N-methylhydroxylamine sulfate with aromatic carbonyl substances. This synthetic pathway for the preparation of isoxazolidines was an ideal process of green chemistry. The synthetic products were 5-substituted isoxazolidines and their structures were characterized by mass and NMR (1H-, 13C-, COSY, HSQC, and DEPT) spectrometry, and their bioactivity was investigated indicating that some new compounds inhibited Botrytis cinerea effectively.
  • Synthesis and surface-active property of bis-quaternary ammonium-sodium sulfate Gemini surfactant
    Zhao Qiuling, Gao Zhinong
    2006, 1(4): 434-437. https://doi.org/10.1007/s11458-006-0050-9
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    N,N-dimethyldodecylamine, hydrochloride and epichlorohydrin (molar ration is 2:1:1) were used to synthesize bis-quaternary ammonium Gemini surfactant with a hydroxyl in its spacer group by the one-pot method. This hydroxyl was sulfonated by chlorosulfonic acid and then neutralized to bis-quaternary ammonium-sodium sulfate zwitterionic Gemini surfactant. The yield of the final product was 78%, and the melting point was 231 233ºC.Its structure was characterized by IR, 1H-NMR, MS, and elemental analyses. The critical micelle concentration (cmc) and surface tension of the novel zwitterionic Gemini surfactant in aqueous solution at 15ºC are 7.2?10-5 mol/L and 34.5 mN/m, respectively.
  • Self-assembly of cetyl trimethylammonium bromide in ethanol-water mixtures
    Li Wei, Zhang Ming, Zhang Jinli, Han Yongcai
    2006, 1(4): 438-442. https://doi.org/10.1007/s11458-006-0069-y
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    The critical micelle concentration (CMC) of cetyl trimethylammonium bromide (CTAB) in both water and ethanol-water-mixed solvent was determined using steady- state fluorescence techniques in order to investigate the effect of the self-assembling properties of the surfactant on the template synthesis of porous inorganic materials. Results indicated that the CMC increased with the increase of ethanol concentration in the mixed solvent. The CMC of CTAB is 0.0009 mol/L in water, while it is 0.24 mol/L in ethanol. Furthermore, the dissipative particle dynamics (DPD) was adopted to simulate the aggregation of CTAB in water and ethanol/water mixtures, and the energy difference was calculated for the surfactant tail groups after mixing with the solvent. The simulation results reflected a regularity similar to the experimental data, i.e., tail groups of CTAB interacted more strongly with ethanol than with water, which elucidates the reason that the micelle is difficult to form in ethanol.
  • Investigation on the acute biochemical effects of light rare earths on rat serum by NMR-based metabonomic approaches
    Li Zhongfeng, Wu Huifeng, Zhang Xiaoyu, Li Xiaojing, Liao Peiqiu, Li Weisheng, Pei Fengkui
    2006, 1(4): 443-447. https://doi.org/10.1007/s11458-006-0060-7
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    1H-NMR spectroscopy and pattern recognition (PR) method were used to assess the acute biochemical effects of light rare earths. Male Wistar rats were treated with both La(NO3)3 and Ce(NO3)3 at doses of 2, 10, and 50 mg/kg body weight. Serum samples from the rats with the two kinds of doses of light rare earths were obtained after 48 h and analyzed by a 600 MHz 1H-NMR spectrometer. Each NMR spectra was data-processed to provide 238 intensity-related descriptors as input coordinates in a multidimensional space and analyzed by PR method. Many low-molecular weight metabolites were identified by 1H-NMR spectra of the rat serum. An increase in ketone bodies, creatinine, lactate, succinate, and various amino acids (valine, leucine, and glutamine) were found from the higher doses (10 and 50 mg/kg body weight) of rare earths-treated groups, together with a decrease of glucose in the serum from Ce(NO3)3-dosed groups. These findings may mean that high-dosage of La and Ce impair a specific region of liver. The similar toxicities with various mechanisms for La and Ce are implicated by NMR-based metabonomic approach. Ce(NO3)3 exhibited a higher toxicity than La(NO3)3 at the same doses.
  • Studies on column size scale-up and flow profile in conical shape liquid chromatographic column of 10? by visualization method
    Guan Wenna, Tan Feng, Guan Yafeng
    2006, 1(4): 448-453. https://doi.org/10.1007/s11458-006-0059-0
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    An improved visualization device made of polymethyl methacrylate (PMMA) was used to study the 3D flow profile inside conical columns of a 10º opening angle packed with C18 phase. The outside wall of the conical columns was rectangular in shape in order to improve the transparency property of the column wall and reduce the deformation of the image for better observation of the flow profiles of colored solutes inside the column. The influence of flow rate, particle size and shape on the flow profile of a colored band were studied on a 5-cm-long column and a scaled-up column of four fold in volume. It was found that the flow rates of the mobile phase had little influence on the flat flow profile of the iodine band while the properties of the stationary phase had a certain influence on them. We observed that the flow profiles of the scaled-up column were flat during the whole chromatographic process, and the efficiency and resolution of the column were also increased in accordance with theoretical prediction. The experimental results proved that the 10º conical columns can be proportionally scaled up while still keeping the flat flow profile, sample load per unit volume of packing material, and column efficiency, which are superior to the conventional column.
  • Identification and characterization of supercritical fluid extracts of Rhizoma Chuanxiong by high performance liquid chromatography ion trap mass spectrometry
    Teng Jiuwei, Li Deliang, Chen Hongwei, Luo Andong
    2006, 1(4): 454-458. https://doi.org/10.1007/s11458-006-0070-5
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    The main constituents, senkyunolide A, Z-ligustilide, neocnidilide, 3-butylphthalide, and ligustilide dimers, in supercritical CO2 fluid extracts of Rhizoma Chuanxiong, a popular Chinese traditional medicine, have been identified and characterized by high performance liquid chromatography tandem mass spectrometry. Separations were carried out on an Agilent (ECLIPSE XDB) C18 analytical column by gradient elution with 0.25% acetic acid and methanol (containing 0.25% acetic acid). An Agilent 1100 series LC/MSD XCT system was operated under positive ESI and auto MS/MS modes for mass spectrometric analysis. Collision- induced dissociation (CID) fragmentations of these phthalides have been investigated and elucidated. Phthalides have primarily undergone two ESI CID pathways: side-chain cleavage with losses of alkenes and ring-opening with eliminations of H2O followed by losses of CO. Direct neutral loss of CO has not been observed. Sodium adduct ions have demonstrated completely different CID pathways.
  • Preparation and application of cross-linked core-shell PBA/PS and PBA/PMMA nanoparticles
    Zeng Zhong, Yu Jian, Guo Zhaoxia, Li Ying
    2006, 1(4): 459-464. https://doi.org/10.1007/s11458-006-0054-5
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    This paper reports the preparation of cross-linked core-shell poly(butyl acrylate )/polystyrene (PBA/PS) and poly(butyl acrylate)/poly(methyl methacrylate) (PBA/PMMA) nanoparticles via seeded emulsion polymerization and their application in nylon-based composites. A highly cross-linked structure was formed in both the cores and the shells by using a cross-linking agent, which could prevent the migration of hydrophobic PS shells to the inside of particles. There were covalent bonds on the interfaces between the cores and the shells of both particles. The average particle sizes were 40-50 nm, and the size distributions were narrow. The kinetics of polymerization was investigated. Well-defined core-shell structure and narrow particle size distribution could be achieved under starved conditions of monomer feeding. Furthermore, PBA/PMMA particles were used to fill nylon 6, good dispersion was obtained because of the strong interfacial interaction between the nanoparticles and the nylon 6 matrix and the good deformation ability of nanoparticles, and the toughness and rigidity of the composites were improved evidently.
  • Crystallization behavior of single or pauci chain aggregates of isotactic polystyrene
    Xin Yan, Yu Ying, Zhang Yu, Fan Zhongyong
    2006, 1(4): 465-468. https://doi.org/10.1007/s11458-006-0044-7
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    Single and pauci chain aggregates of isotactic polystyrene (i-PS) were prepared by the freeze-drying process from dilute solutions with the concentration from 1?10-3 to 2?10-5 g/mL. It was found by DSC measurements that the melting point of samples gradually shifted to lower temperatures with the decrease of the solution concentration used for sample preparation. As a result, the lamella thickness of bulk samples and the samples prepared by the freeze-drying process from a solution of 2?10-5 g/mL was 19.3 and 12.6 nm, respectively. At 468.3 K the half crystallization time (t1/2) of samples freeze-dried from a solution of 1?10-4 g/mL was about 36 s, which was merely one tenth of that of the bulk sample. In addition, the growth rate of spherulite (dr/dt) of samples prepared from a solution of 2?10-5 g/mL was faster than that of the bulk sample annealed at 478.3 K. All these results should be attributed to the fewer entanglements in samples prepared by freeze-drying process from dilute solutions, and presented clear evidence for the influence of chain entanglements on the crystallization behavior of polymers.
  • Synthesis of dendritic polyamide with protected amino functional groups in the periphery
    Ye Li, Meng Chao, Zhang Xiuqiang, Zhang Afang
    2006, 1(4): 469-473. https://doi.org/10.1007/s11458-006-0066-1
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    A homologous series of first- to third-generation dendritic polyamides 2a, 3, and 5 with tris(aminoethyl) amine (TREA) as the core and the protected amino functional groups at the periphery were synthesized via active ester route from Schl?ter  type dendron 1a. Their structures were characterized by 1H-NMR and mass spectra. Based on the efficient synthesis of the first generation dendrimer 2a (yield 75%), the synthesis of second-generation dendrimer 3 was found to be more efficient via the convergent method (yield 69%), while the mixed strategy was applied efficiently for the synthesis of the higher generation dendrimer 5 (yield 37%). The overall yield for the third generation dendrimer 5 from Schl?ter dendron is 12%.
  • Preparation and properties of polymer and quantum dot composites
    Tian Hongye, Shao Jun, He Rong, Gao Feng, Cui Daxiang, Gu Hongchen
    2006, 1(4): 474-478. https://doi.org/10.1007/s11458-006-0053-6
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    Quantum dots (QDs) were prepared in an organic system through a simple and low-cost wet chemistry method. Polymer beads with a diameter of 60 70 nm and specific functional groups were synthesized by a particular seeded emulsion polymerization technique. QDs were embedded in the polymer beads with the specific functional groups through dissolving and swelling method, which provided the condition for the conjunction of biomolecules and QDs as fluorescent probes. The prepared composites were characterized with UV-Vis, PL, TEM, FTIR, CLSM and conductance titration etc. The results show that QDs are successfully embedded in polymer beads, which breaks the limitation that the conjunction of biomolecules and QDs can be achieved only for those synthesized in aqueous system.
  • Synthesis and properties of liquid crystalline polyurethanes
    Xin Haobo, Zhang Yunfeng, Xing Zheng
    2006, 1(4): 479-483. https://doi.org/10.1007/s11458-006-0055-4
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    1,4-Bis(p-hydroxybenzoate)phenylene was prepared using 1,4-bis(trimethylsiloxy)benzene andp-hydroxybenzoyl chloride as starting materials. A series of novel 1,4-bis(p-hydroxyalkoxybenzoate)phenylene were synthesized by reaction of 1,4-bis (p-hydroxybenzoate) phenylene with 3-bromopropanol and 4-bromobutanol, respectively. The liquid crystal polyurethanes were prepared by 1,4-bis(p-hydroxyalkoxybenzoate)phenylene with MDI (p-methylene diphenylenediisocyanate) and 2,4-TDI(2,4-toluenediisocyanate), respectively. The thermotropic properties, the melting point (Tm) and the isotropization temperature (Ti) of the synthesized polyurethanes were characterized by DSC, IR and POM. It showed that all of the polyurethane polymers exhibited thermotropic liquid crystalline properties between 144ºC and 260ºC. The transition temperature (Tm and Ti) decreased with an increase in the length of the methylene spacer.
  • Preparation of PANI/PSF conductive composite films and their characteristic
    Yang Yuying, Kong Chao, Zhao Hongxiao, Hu Zhong′ai, Shang Xiuli
    2006, 1(4): 484-487. https://doi.org/10.1007/s11458-006-0063-4
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    Polyaniline (PANI)/polysulfone (PSF) composite films are successfully prepared by phase separation and one-step in-situ polymerization. It is found that the head-on face (in contact with solution) of the films is green while the back face is white. The chemical component and the surface morphology of both surfaces of the films are characterized by FT-IR spectra and SEM, respectively. The effect of the polymerization temperature, time and concentration of the reactants on the electrical properties of the films are discussed in details. The thermo-oxidative degradation of the films is studied by thermogravimetric analysis (TGA). The results indicate that the thermal stability of the PANI/PSF films is higher than that of the pure PSF film.