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Xia C.,Anhui University of Science and Technology | Ding X.,Anhui University of Science and Technology | Sun Y.,Anhui University of Science and Technology | Liu H.,Anhui University of Science and Technology | Li Y.,State Key Laboratory of Polymer Physics and Chemistry
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2010

Novel amphiphilic hyperbranched-upon-dendritic polymers with a dendritic polyester core, a linear poly(ε-caprolactone) (PCL) inner shell, and a hyperbranched polyglycerol outer shell have been prepared. The structures of the hyperbranchedupon-dendritic polymers were characterized by using NMR spectra. The critical aggregating concentrations (CACs) of those amphiphilic hyperbranched-upon-dendritic polymers were measured by using pyrene as the polarity probe. To study the encapsulation performances of those hyperbranched-upon-dendritic polymers as unimolecular hosts, inter-molecular encapsulation was carefully prevented by controlling the host concentrations below their CACs and by washing with good organic solvents. The study on encapsulation of two model guest molecules, pyrene and indomethacin, was performed. The amounts of encapsulated molecules were dependent mainly on the size of inner linear shells. About three pyrene molecules or five indomethacin molecules were encapsulated in hyperbranched-upon-dendritic polymers with average PCL repeating units of two but different hyperbranched polyglycerol outer shells, whereas about five pyrene molecules or about 12 indomethacin molecules were encapsulated in those with PCL repeating units of nine. The encapsulated molecules could be released in a controlled manner. Thus, the hyperbranched-upon-dendritic polymers could be used as unimolecular nanocarriers with controllable molecular encapsulation dosage for controlled release. © 2010 Wiley Periodicals, Inc. Source


Ma P.,Anhui University of Science and Technology | Nie H.,Anhui University of Science and Technology | Zhou Q.,Anhui University of Science and Technology | Li Y.,State Key Laboratory of Polymer Physics and Chemistry | Liu H.,Anhui University of Science and Technology
Advanced Materials | Year: 2012

A one-pot polymerization strategy is put forward for producing 1D polymeric nanomaterials directly from a single inimer. An inimer bearing an NMP initiating site is polymerized in the presence of a RAFT CTA to form a pearl-necklace structure constituted of hyperbranched polymer "pearls". The obtained 1D nanorods show high regularity evidenced by the long-range order in small angle XRD patterns and the formation of liquid crystalline phases. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Li C.,Anhui University of Science and Technology | Liu H.,Anhui University of Science and Technology | Li Y.,State Key Laboratory of Polymer Physics and Chemistry
Macromolecular Chemistry and Physics | Year: 2011

A new 1,2,3-triazole incorporated diacrylate monomer is designed for free radical cyclopolymerization through the formation of 11-membered rings. NMR analysis on the cyclopolymers including 1H, 13C, DEPT-135, and 1H-13C HMQC spectra support a high degree of cyclization. GPC profiles of the obtained cyclopolymers show unimodal distributions indicative of no chain branching reactions. A new 1,2,3-triazole incorporated diacrylate monomer is designed for free radical cyclopolymerization through the formation of eleven-membered rings. Structural analysis of the cyclopolymers based on NMR analysis including 1H, 13C, DEPT-135, and 1H-13C HMQC spectra supports a high degree of cyclization. GPC profiles of the cyclopolymers show unimodal distributions indicative of no chain branching reactions. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Liu H.,Anhui University of Science and Technology | Shen R.,Anhui University of Science and Technology | Song K.,Anhui University of Science and Technology | Li Y.,State Key Laboratory of Polymer Physics and Chemistry
ChemPhysChem | Year: 2012

Reduction of bare carbon dots (CDs) in aqueous NaBH4 solution is a facile and effective approach to enhance their fluorescence without any surface coverage. CDs are treated with dilute aqueous NaBH4 solutions, enhancing their quantum yields (QYs) successfully from 1.6 % to 16 % which is comparable to semiconductive QDs in aqueous environments. If pristine CDs are treated hydrothermally prior to reduction by NaBH4, QYs reach 40.5 %. This value is among the highest QYs reported for bare CDs in the literature. The approach to enhance fluorescence through chemical reduction is generally applicable to other kinds of CDs synthesized by various methods. Alteration of the chemical structure of the CDs by NaBH4-reduction is analyzed by 13C NMR, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, which demonstrate that the carbonyl group content is decreased after NaBH4-reduction, whereas the number of sp 3-type carbon defects is increased. The valence-band maxima (VBM) near the surface related to the surface energy bands of the CDs are estimated by XPS. VBM data show a semiconducting layer on the surface of the CDs, and the VBM of the CDs decrease with increasing NaBH4-reduction time. The layered graphite structures in the cores of the CDs are clearly observed by transmission electron microscopy (TEM). CDs could perhaps be regarded as semiconductive surface defect layers formed by chemical erosion over conductive graphite cores. Chemical reduction by NaBH4 changes the surface-energy bands of the CDs, thus, enhances their fluorescence. The fluorescence properties of aqueous NaBH4-reduced CDs are also studied for possible biological applications. Reduce to improve: Reduction by aqueous NaBH4 is an efficient way to enhance the fluorescence of aqueous carbon dots (CDs). We found that the structure of CDs can be regarded as semiconductive surface layers over conductive graphite cores (see picture). Chemical reduction increases the number of surface defects leading to conjugation of the defect areas. Thus, the surface is changed to improve fluorescence properties. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Cheng Z.,State Key Laboratory of Rare Earth Resource Utilization | Xing R.,State Key Laboratory of Polymer Physics and Chemistry | Hou Z.,State Key Laboratory of Rare Earth Resource Utilization | Huang S.,State Key Laboratory of Rare Earth Resource Utilization | Lin J.,State Key Laboratory of Rare Earth Resource Utilization
Journal of Physical Chemistry C | Year: 2010

Printed electronics is expected to be used for fabricating the next-generation displays. However, this technique is still in the laboratory scale and mainly limited to organic luminescent materials and inorganic quantum dots. In this article, a new attempt was made by combining the Pechini-type sol-gel process and inkjet printing for patterning an inorganic YVO 4:Eu3+ thin film phosphor. The mixed solution of metal salts precursors, citric acid, and poly(ethylene glycol) was directly used as ink to deposit patterns on ITO-coated glass substrate. After calcination at 600°C in air, the YVO4:Eu3+ patterns in micrometer-scale were formed on the substrates, and the photoluminescence (PL) and cathodoluminescence (CL) spectra were employed to characterize the obtained samples. A dominating red emission coming from 5D0- 7F2 transition of Eu3+ was observed under excitation of UV light or electronic beam. These results demonstrate that the Pechini-type sol-gel process has good compatibility with the inkjet printing technique and has the potential to be used for fabricating the next-generation Field Emission Display (FED) devices. © 2010 American Chemical Society. Source

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