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ABSTRACT: The structure and chain dynamics of polyethylene oxide (PEO)/LiClO(4) complex crystals were studied by employing state-of-the-art solid-state (13) C NMR techniques. Remarkable helical jump motions of the PEO segments in the complex crystals at ambient temperatures were clearly demonstrated. The jump motions are believed to induce the transportation of the coordinated Li(+) ions along the crystallographic c axis, providing a novel mechanism of ionic conductivity of the complex crystals. In addition, this work also shows that solid-state high-resolution (13) C NMR spectroscopy can be a powerful and general tool for elucidating phase structures, dynamics, and subsequently the conduction mechanism of crystalline polymer electrolytes.
Chemistry 06/2011; 17(32):8941-6. · 5.93 Impact Factor
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ABSTRACT: Hyperbranched poly(amido amine)s (HPAAs) containing different amounts of β-cyclodextrin (β-CD) (HPAA-CDs) were synthesized in one-pot by Michael addition copolymerization of N,N'-methylene bisacrylamide, 1-(2-aminoethyl)piperazine, and mono-6-deoxy-6-ethylenediamino-β-CD. In comparison to pure HPAA, the fluorescence intensity of HPAA-CDs was enhanced significantly while the cytotoxicity became lower. Ascribed to plenty of amino groups and strong photoluminescence, HPAA-CDs could be used as nonviral gene delivery vectors, and the corresponding gene transfection was evaluated. The experimental results indicated that HPAA-CDs condensed the plasmid DNA very well. By utilizing the fluorescent properties of HPAA-CDs, the cellular uptake and gene transfection processes were tracked by flow cytometry and confocal laser scanning microscopy without any fluorescent labeling. The transfection efficiencies of HPAA-CDs were similar to that of pure HPAA. In addition, the inner cavities of β-CDs in HPAA-CDs could be used to encapsulate drugs through host--guest interaction. Therefore, the HPAA-CDs may have potential application in the combination of gene therapy and chemotherapy.
Bioconjugate Chemistry 06/2011; 22(6):1162-70. · 4.93 Impact Factor
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Yan Chen,
Yan Pang,
Jieli Wu,
Yue Su,
Jinyao Liu,
Ruibin Wang,
Bangshang Zhu,
Yefeng Yao,
Deyue Yan,
Xinyuan Zhu, Qun Chen
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ABSTRACT: A new method to adjust the particle size of interpolymer complexes has been developed by introduction of host-guest interaction into the dilute aqueous solution of poly(acrylic acid) (PAA) and poly(ethylene glycol) (PEG). Because of the cooperative hydrogen-bonding interaction, PAA can form the interpolymer complexes with PEG. Putting beta-cyclodextrin (beta-CD) into dilute PAA/PEG aqueous solution, the competition between host-guest and hydrogen-bonding interactions happens. The beta-CD/PAA/PEG ternary systems have been well characterized by ultraviolet-visible absorption spectroscopy (UV-vis), dynamic light scattering (DLS), transmission electron microscopy (TEM), diffusion NMR spectroscopy, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), and solid-state (13)C NMR spectroscopy. The results indicate that the hydrophobic cavity of beta-CD is threaded by linear polymers so that the hydrophilicity of PAA/PEG interpolymer complexes is improved greatly. Adjusting the amounts of beta-CD, the particle size of the interpolymer complexes can be readily controlled. The low cytotoxicity of various beta-CD/PAA/PEG ternary complexes has been confirmed using the MTT assay in COS-7 cell line. Doxorubicin (DOX), an anticancer drug, has been encapsulated into the beta-CD/PAA/PEG ternary complexes. The DOX-loaded beta-CD/PAA/PEG ternary complexes have been analyzed by confocal laser scanning microscopy (CLSM), flow cytometry analysis, and the MTT assay against human cervical carcinoma cell (Hela). The results indicate that beta-CD/PAA/PEG ternary complexes with controlled particle size could be used as safe and promising drug carriers.
Langmuir 06/2010; 26(11):9011-6. · 4.19 Impact Factor
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ABSTRACT: By simply heating mixtures of alpha-cyclodextrins and dumbbell-like poly(ethylene glycol) derivatives at 120 degrees C, polyrotaxanes form spontaneously via reversible chain exchange between acylhydrazone bonds, which have been proven by analyses of diffusion-ordered NMR, WAXD, 1H NMR, solid-state 13C CP/MAS NMR, DSC and UV-Vis together.
Chemical Communications 01/2009; · 6.17 Impact Factor
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ABSTRACT: Semi-crystalline polymer nanocomposites were prepared using successive meltings and recrystallizations techniques by intercalation of small guest molecules such as 4-chlorotoluene (PCT), 4-bromotoluene (PBT) and 1,4-dibromobenzene (PDBB) into poly(ethylene oxide) (PEO) crystals. Differential scanning calorimetry, Fourier transform infrared spectroscopy and wide-angle X-ray diffraction experimental results show that supramolecular selectivity exists for the PEO–PDBB/PBT ternary system, while there is no supramolecular selectivity for PEO–PCT/PBT ternary nanocomposites. The interactions between PEO chains and small guest molecules have an important influence on the polymer conformation, which results in the dramatic difference in intercalation behavior. Copyright © 2007 Society of Chemical Industry
Polymer International 05/2007; 56(12):1558 - 1562. · 1.90 Impact Factor
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ABSTRACT: In this paper, a new method based on sol−gel process was developed to prepare polymer/carbon nanotube composites. By modifying the multiwalled carbon nanotube (MWNT) with coupling agent, MWNT was introduced into the polyurethane−urea (PU) system by chemical linkages, and a series of novel self-cross-linkable PU/MWNT composites were then prepared. The obtained PU/MWNT composites with various MWNT contents are homogeneous and transparent materials. Mechanical property measurements show that a small amount of MWNT in the samples may increase the Young's modulus and tensile strength significantly with no loss of elongation, indicating that MWNT is an excellent reinforcing agent for polyurethane. The PU/MWNT composites also show good optical limiting properties. The normalized extinction increases and the optical limiting threshold decreases with the increase of the contents of MWNT. Thus, it is possible to change the required transmittance and transmitted energies by changing the MWNT contents in composites.
04/2006;
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Angewandte Chemie International Edition 01/2006; 45(1):87-90. · 13.45 Impact Factor
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ABSTRACT: A new class of crystalline inclusion complexes of a multiarm hyperbranched polyether combined with various cyclodextrins (CDs) was successfully prepared. Using self-condensing ring-opening polymerization, a kind of multiarm polyether with a hyperbranched poly(3-ethyl-3-oxetanemethanol) core and multiple linear poly(ethylene glycol) (PEG) arms was obtained. It has been found that this kind of hyperbranched polyether can be dissolved in water. Adding alpha-CDs to the multiarm hyperbranched polyether solution, molecular recognition results in the formation of crystalline inclusion complexes based on the noncovalent interactions between the linear PEG arms of the polyether particles and the alpha-CDs. These multiarm polyether inclusion complexes have been well characterized. Interestingly, quite different from inclusion complexes of CDs and linear polymeric guests, the complexes of the multiarm hyperbranched polyether with alpha-CDs show a novel lamellar morphology. The experimental results validate that the resultant lamellar crystals have a juxtaposed structure. In addition, the formation mechanism of these inclusion complexes of a multiarm polyether with alpha-CDs has also been well described. Besides the role of displacement of associated water molecules and the presence of hydrogen bonding between CDs in channel structure CD inclusion complexes, the noncovalent intermolecular forces between CDs and polymers also play an important role in the formation of complex architectures.
Langmuir 02/2004; 20(2):484-90. · 4.19 Impact Factor
