Table of Content

15 November 2012, Volume 30 Issue 6

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Photo-Induced Isomerization Reaction of Ruthenium Complexes

JIN Xiao-wei, WANG Jian-ru, DUAN Qing-qing, QIAO Xiao-yan, WANG Hong-fei

2012, 30(6):  401-410.  DOI: 10.7517/j.issn.1674-0475.2012.06.401

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Ruthenium (Ru) complex, are among the most investigated in fields that include solar energy conversion, photocatalysis and molecular recognition, owing to their favorable photophysical and photochemical properties as well as ground state and excited state reactivity. The photo-induced isomerization is one kind of novel reactions for ruthenium complexes, and the study for photo isomerization is of great significance for the light energy conversion, information storage, as well as the design for "molecular switch" and "molecular motor". Herein, the different types, characteristics and mechanism of photo-induced isomerization of ruthenium complexes as well as the recent progress were reviewed.

Effects of Triplet Energy Levels of Phosphorescent Guests on Luminescent Efficiency of PVK Based Polymeric Light-Emitting Diodes

LIU Hong-mei, YIN Ming, WANG Peng-fei, HE Jian, ZHANG Xiao-hong, ZHANG Xin-ping

2012, 30(6):  411-419.  DOI: 10.7517/j.issn.1674-0475.2012.06.411

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Doping phosphorescent guests to PVK and PBD matrix is an effective method to achieve high-efficiency phosphorescent polymeric light-emitting diodes (PhPLED). However, by doping Ir(pppy)₃, Ir(F-pppy)₃ and Ir(F₂-pppy)₃ to the PVK and PBD matrix, great difference of the device properties have been observed. In order to investigate the reasons for these phenomena, we use steady- and time-resolved-spectroscopy to study the effect of energy transfer from host to guest and direct electron and hole trapping mechanisms on the light-emitting properties of the active layers. The experimental results show that the balanced carrier injection and high efficient charge trapping are important mechanisms for obtaining high-efficiency PhPLEDs with PVK as the host. PVK does not fit blue PhPLED preparation because of its lower triplet energy level. Doping PBD to PVK host will further decrease the triplet energy level of the host. Our work provides important photophysical basis for the design of the phosphorescent hosts and the PhPLED device.

Synthesis and Dual-Responsive Assembling Behavior of Double Hydrophilic Acrylamide/Acrylic Acid Comb-Like Polymers

YUE Guo-liang, ZHANG Yu-xi, WU Fei-peng

2012, 30(6):  420-428.  DOI: 10.7517/j.issn.1674-0475.2012.06.420

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Double hydrophilic acrylamide/acryl acid comb-like polymers (CS-PAM/PAA) were successfully developed via successive radical polymerization of acrylamide (AM) and acrylic acid (AA) in which triggered amount chitosan (CS) was employed as backbone. The composition of AM and AA in polymers could be regulated by controlling the reaction time, while the ratio was elucidated roughly by ¹³CNMR in a quantitative way. The polymers showed the typical properties of double hydrophilic block copolymers. Both good pH sensitivity and ion responsiveness were displayed by the polymers aqueous solutions. CS-PAM/PAA could molecularly dissolve in water and self-assemble into vesicular aggregates in the acid condition. In addition, the responsive assembling behavior of polymers could also be induced by multivalent metal ions (e.g. Tb³⁺).

Syntheses, Characterization and Property Studies on Porphyrinic Polynorbornenes

LI Hui, FENG Ke, ZHOU Li, CHEN Bin, ZHANG Li-ping, TONG Zheng-he(TUNG Chen-ho), WU Li-zhu

2012, 30(6):  429-437.  DOI: 10.7517/j.issn.1674-0475.2012.06.429

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Porphyrinic and long-chain alkyl norbornene monomers have been designed and synthesized, and copolymers were obtained via ROMP (ring-opening metathesis polymerization) using a Grubbs' initiator. The properties of porphyrinic polynorbornenes have been investigated by UV-Vis absorption spectroscopy, steady-state fluorescence spectroscopy, lifetime measurements and electrochemistry. The copolymers exhibit almost identical characteristics as well as porphyrinic monomers in photophysics and electrochemistry.

Control/Living Free Radical Photopolymerization of n-Butyl Methacrylate in O/W Microemulsion

ZHANG Yong-tao, YAO Yong-ping, CUI Yan-yan, DONG Zhi-xian, LIU Xiao-xuan

2012, 30(6):  438-446.  DOI: 10.7517/j.issn.1674-0475.2012.06.438

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Using 2-bromo-(2-methyl-1-oxopropoxy)-2-methyl-propio-phenone(HMPP-Br) as a photoinitiator, the controlled/living photopolymerization of n-butyl methacrylate(n-BMA) mediated by 2,2,6,6-tetramethyl-piperidinyl-l-oxyl(TEMPO) and 2,2,6,6-tetramethyl-4-piperidinol(TMP) in the microemulsion of n-BMA/n-butanol/SDS-H₂O system (O/W) was performed at ambient temperature.The controlling mechanism and reaction kinetics of controlled/living free radical photopolymerization of n-BMA in microemulsion was investigated. It was shown that the monomer conversion increased linearly with the increased exposure time, and the number-average molecular weight (M_n) of Poly(n-BMA) is increased linearly with the monomer conversion increasing under the condition with[TEMPO+TMP]/[HMPP-Br]=1.1, the content of initiator of 4.5%(mass fraction) and the irradiation intensity of 5.5 mW/cm². The results show that when it was mediated by TEMPO/TMP, the photopolymerization of n-BMA in the microemulsion was to be kineticly controlled. It was found that the plots of number-average molecular weight vs. conversion and ln([M]₀/[M]) vs. time were liner respectively, and the n-BMA homopolymers exhibited relatively narrow molecular weight distributions (PDI=1.25—1.45), even until the conversion was up. This shows that TEMPO combined with TMP used as a mediator was evidently available.

Synthesis and Properties of Hollow Glass Spheres/ TiO₂ Composite

YUAN Jing, AN Zhen-guo, ZHANG Jing-jie, LI Bing

2012, 30(6):  447-455.  DOI: 10.7517/j.issn.1674-0475.2012.06.447

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Anatase TiO₂ shells deposited on hollow glass microspheres with tunable morphologies were successfully prepared through a controllable chemical precipitation method with urea as the precipitator, and thus glass/TiO₂ core/shell composite hollow microspheres were fabricated. The phase structure, morphology, particle size, shell thickness, and the chemical compositions, of the composite microspheres were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrum and Raman spectra. The probable growth mechanism of the TiO₂ shells and the formation process of the core/shell composite microspheres were proposed.

Synthesis, Characterization and Photocatalytic Hydrogen Production of Water-Soluble Pt(II)-Salen Complex

FAN Ren-jie, CHEN Yong, FU Wen-fu

2012, 30(6):  456-462.  DOI: 10.7517/j.issn.1674-0475.2012.06.456

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A new water-soluble Pt(II) -Salen complex (Salen=NN'-substituted bis(salicyl-aldimine-5-sulphonic acid) potassium salt) was synthesized, characterized and employed in the photocatalytic hydrogen evolution system. In the presence of TEA, this system could produce hydrogen effectively without additional catalyst. An investigation found that the Pt(II) -Salen complex could be employed as photosensitizer. Besides, it could also be the precursor of the catalyst. In addition, there was not organic solvent except TEA in the hydrogen evolution system. The result provided a new way to simplify the multi-component system for photocatalytic hydrogen production.

Study on Photopolymerization Properties of Vinyl Ether Monomers with Different Functionalities

XIN Yang-yang, XIAO Shi-zhuo, ZHOU Shu-yun, CHEN Ping, ZOU Ying-quan

2012, 30(6):  463-470.  DOI: 10.7517/j.issn.1674-0475.2012.06.463

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A difunctional vinyl ether and a trifunctional vinyl ether bearing carbamate-based monomers were synthesized and characterized. In this paper, the mono-, di- and tri-functional monomers were successfully polymerized by UV irradiation in the presence of photo initiator, mixed type triarylsulfonium hexafluoro antimonate salts (PAG-201). The polymerizing process was monitored by real-time infrared spectroscopy and the photopolymerization kinetics of the three monomers was compared. The influence of the concentrations of PAG-201 on photopolymerization of difunctional vinyl ether was also investigated. The results showed the double bond conversion and the rate of polymerization would decrease with the increase of the functionality, meanwhile, the thermo-stability of their polymerized products were improved with the increase of the functionality revealed by DSC. The above results were instructive to the research and development of cationic polymerization system of vinyl ether bearing carbamate-based monomers.