Qingmin Chen
Nanjing University
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Publication
Featured researches published by Qingmin Chen.
Journal of Applied Polymer Science | 1999
Quli Fan; Jianglin Fang; Qingmin Chen; Xuehai Yu
A series of polyurethanes with different siloxane contents were synthesized, which were based on 4,4′-methylene diphenyl diisocyanate (MDI), poly(tetramethylene oxide) (PTMO), aminoethylaminopropyl poly(dimethyl siloxane) (AEAPS), and butanediol (BD). The chemical compositions, structures, and bulk and surface properties were investigated using an infrared surface quantitative analysis technique (FTIR-ATR), surface contact angle, electron spectroscopy for chemical analysis (ESCA), stress–strain analysis, and dynamic mechanical thermal analysis (DMTA). It was shown that siloxane concentration on the surface region of the elastormers was higher than that in the bulk for a resulting surface enrichment of the siloxane, and the tensile properties of these elastomers were not changed significantly with the AEAPS modification.
Polymer | 2001
Jiangning Chen; Junfeng Zhang; Tongyang Zhu; Zichun Hua; Qingmin Chen; Xuehai Yu
Abstract A series of blends of thermoplastic polyurethane(PU) and polyether–polyimide (PI) were prepared in two steps. The first step was the preparation of polyether–amic acid by the reaction of an oligmer based on polytetramethylene oxide glycol di-p-aminobenzoate (APTMO) of different molecular weight (650, 1000, and 2000) with benzenetetracarboxylic acid dianhydride (PMDA). The second step was mixing polyether–polyurethane and polyether–polyamic acid solution at room temperature in various weight ratios, and the blend films were obtained by casting and then heat imidization. Infrared spectroscopy (IR), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), small-angle X-ray scattering (SACS) and wide-angle X-ray diffraction(WAXD) were used to study this family of blends. DSC analysis of the films showed that glass transition temperature (Tg) of PU–PI 650 and PU–PI 1000 series shifted depending on the ratio of PU and PI components. The shift of Tg, along with the transparency of the films, gave the evidence that soft segments of PU and PI were miscible to some extent in the PU–PI 650 and PU–PI 1000 series. DMA results indicated that the blends exhibited a well phase-separated structure and had a broad rubbery plateau from about −30 to 200°C, which varied with the PU content. Thermal stability of PU was found to increase by the incorporation of PI. The excellent tensile properties of the blends suggested that they could be potentially used as heat resistant thermoplastic elastomers.
Organic Letters | 2015
Kun Chen; Huiru Zhao; Zhaokang Fan; Gui Yin; Qingmin Chen; Yiwu Quan; Shuhua Li; Shanghui Ye
A novel bipolar oligomer (TPA-PO)3 was prepared as a host material for efficient blue phosphorescent organic light-emitting diodes (OLEDs). Through the C-9s of the fluorene units, three triphenylamine units attached to diphenylphosphine oxide are connected in series to form a macrocyclic structure. The solution-processed phosphorescent device based on FIrpic and (TPA-PO)3 achieved a maximum current efficiency of 19.4 cd A(-1) and a maximum luminance of 11,500 cd m(-2) with a relatively low efficiency roll-off.
Journal of Materials Chemistry C | 2014
Zhaokang Fan; Nengquan Li; Yiwu Quan; Qingmin Chen; Shanghui Ye; Quli Fan; Wei Huang; Hui Xu
A novel triphenylamine-fluorene oligomer with macro-spirocyclic structure was designed and prepared as a host for exciplex based white phosphorescent organic light-emitting diodes (white PhOLEDs), in which only iridium(III)bis(4,6-(difluorophenyl)pyridinato-N,C2)picolinate (FIrpic) was employed as the dopant. The device exhibited a comparatively high performance with a maximum luminance and current efficiency of 14 213 cd m−2 and 22.6 cd A−1, respectively.
ACS Applied Materials & Interfaces | 2015
Zhaokang Fan; Huiru Zhao; Nengquan Li; Yiwu Quan; Qingmin Chen; Shanghui Ye; Shuhua Li; Ying Wang; Quli Fan; Wei Huang
Three bipolar hosts, namely TPA-DAF, TPA-DAF2, and TPA-DAF3, comprising an electron-donating triphenylamine (TPA) group and electron-accepting 4,5-diazafluorene (DAF) units are investigated for phosphorescent organic light-emitting diodes (PhOLEDs). Given the nonplanar structure of the sp(3)-hybridized C9 atom in DAF unit, these molecules have a highly nonplanar configuration, good film-forming property, and high triplet energy (ET) of 2.88-2.89 eV. Among them, TPA-DAF shows more balanced carrier injecting/transporting ability, suitable highest occupied molecular orbital (MO) energy level and higher current density, and therefore TPA-DAF-based devices exhibit the best performances, having an extremely slight efficiency roll-off with current efficiency of 20.0 cd/A at 973 cd/m(2), 19.5 cd/A at 5586 cd/m(2), and 17.6 cd/A at 9310 cd/m(2) for blue PhOLEDs; 23.5 cd/A at 1059 cd/m(2) and 15.3 cd/A at 8850 cd/m(2) for green PhOLEDs; and 12.2 cd/A at 1526 cd/m(2), 10.5 cd/A at 5995 cd/m(2), and 9.2 cd/A at 8882 cd/m(2) for red PhOLEDs, respectively. The results also provide a direct proof for the influence of charge balance on the device performance.
Organic Letters | 2011
Yu Lu; Yu Zhou; Yiwu Quan; Qingmin Chen; Runfeng Chen; Zhiyong Zhang; Quli Fan; Wei Huang; Jianfu Ding
Monodisperse macrospirocyclic oligomers were prepared using self-condensation of the Friedel-Crafts reaction. Through the C-9s of the central fluorene units of four surrounding oligofluorenes, four carbazole units are connected in a series to form a macrocyclic core. These rodlike oligofluorenes form a rigid three-dimensional structure, affording the resulting macrocyclics a high steric hindrance for close interchain packing.
Journal of Applied Polymer Science | 1996
Jiangning Chen; Qingmin Chen; Xuehai Yu
The polyether-ester polyamic acid imidization process in a solid state was studied by microwave radiation. The imidization content at different radiation times was calculated quantitatively by FTIR and was confirmed by the results of dynamic mechanical analysis (DMA). The microwave radiation imidization may drop the reaction temperature and cut the reaction time down in comparison with the thermal imidization. It may be expected theoretically that the microwave radiation may generally be suitable for the condensation polymerization reaction and facilitates the reaction, especially at its later stage.
Journal of Applied Polymer Science | 1994
Qingmin Chen; Hanhua Ge; Dongzhong Chen; Xiangdong He; Xuehai Yu
Journal of Applied Polymer Science | 2008
Dan Xu; Zhen Meng; Ming Han; Kai Xi; Xudong Jia; Xuehai Yu; Qingmin Chen
Journal of Applied Polymer Science | 2003
Yiwu Quan; Qingjun Wang; Wenzhao Dong; Qingmin Chen