Jiang Lu

Sun Yat-Sen University, Shengcheng, Guangdong, China

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Publications (32)83.82 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A well-defined block copolymer polystyrene-block-poly(2-hydroxy-5-vinylbenzaldehyde) (PS-b-PHVB) was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization of HVB using a trithiocarbonate terminated polystyrene macro-chain transfer agent. Sequential grafting of monoamine-terminated PEG (PEG–NH2) and 2-(2-aminoethoxy)ethanol (AME) onto the HVB blocks of PS-b-PHVB via aldehyde–amine condensation afforded an amphiphilic block copolymer PS-b-(PHVB-g-PEG-and-AME) bearing a pendant salicylidene Schiff base with a precise structure. PS-b-(PHVB-g-PEG-and-AME) could self-assemble in ethanol into micelles with salicylidene Schiff base groups at the core–shell interface. Addition of Zn2+ ions into the resulting micellar solution not only endowed the micelles with fluorescent features but also enabled the resulting luminescent micelles to be stabilized through ionic cross-linking in consequence of the salicylaldimine–Zn2+ complexation. The obtained fluorescent cross-linked micelle was “light-controllable” in terms of its fluorescence emission and cross-linking structure due to the reversibility of the salicylaldimine–Zn2+ coordinative bond in response to light stimuli. The reversible fluorescence decrease and recovery could be achieved periodically upon alternative 254 nm UV irradiation and maintaining in the dark, and the micelles could be de-stabilized by UV irradiation-induced de-cross-linking. The capture of guest molecules and the light-triggered release of the guests for this Zn2+ coordinated micelle were also demonstrated using the coumarin-153 dye as a model guest molecule.
    Polym. Chem. 06/2014; 5(14).
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    ABSTRACT: A facile synthetic pathway to a multi-arm star graft polymer has been developed via a grafting-onto strategy using a combination of a reversible addition–fragmentation chain transfer (RAFT) arm-first technique and aldehyde–aminooxy click reaction. A star backbone bearing aldehyde groups was prepared by the RAFT copolymerization of acrolein (Ac), an existing commercial aldehyde-bearing monomer, with styrene (St), followed by crosslinking of the resultant poly(St-co-Ac) macro-RAFT agent using divinylbenzene. The aldehyde groups on the star backbone were then used as clickable sites to attach poly(ethylene glycol) (PEG) side chains via the click reaction between the aldehyde groups and aminooxy-terminated PEG, leading to a structurally well-defined star graft copolymer with arms consisting of poly(St-co-Ac) as backbone and PEG as side chains. Crystalline morphology and self-assembly in water of the obtained star graft copolymer were also investigated. Opportunities are open for the star graft copolymer to form either multimolecular micelles or unimolecular micelles via control of the number of grafted PEG side chains. © 2013 Society of Chemical Industry
    Polymer International 06/2014; 63(6). · 2.13 Impact Factor
  • Qiangfang He, Hui Liang, Jiang Lu
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    ABSTRACT: Living/controlled polymerization of a salicylaldehyde-functionalized vinyl monomer, 2-hydrox-5-vinylbenzaldehyde (HVB), was achieved by reversible addition–fragmentation chain transfer (RAFT) polymerization with S-1-dodecyl-S′-(α,α′-dimethyl-α′′-acetic acid)trithiocarbonate as the RAFT agent in THF at 65 °C. The resulting well-defined polymer with pendant salicylaldehyde groups could react directly with mono-6-deoxy-6-aminoethyl-β-CD to yield a new β-CD-containing polymeric salicylidene Schiff base PHVB-graft-β-CD with precise structure and high solubility. PHVB-graft-β-CD was then coordinated with zinc ions to give the luminescent PHVB-graft-β-CD/Zn2+ complex which displayed intense blue fluorescence with a maximum emission peak around 452 nm in DMF. The obtained PHVB-graft-β-CD/Zn2+ tended to self-aggregate in aqueous media because of the hydrophobic nature of PHVB-graft-β-CD backbone, and therefore its fluorescence emission in water was weak as a result of the aggregation-induced fluorescence quenching. An obvious decrease of the aggregate size from 290 nm to 40 nm in aqueous media was observed after adding 1.0 equiv. (relative to β-CD moieties) of the guest molecule, sodium adamantanecarboxylate (Ad-COONa), and concomitantly a remarkable fluorescence enhancement (4.5-fold) was obtained due to a better water-dispersibility of PHVB-graft-β-CD/Zn2+. The incorporation of carboxylic groups on the PHVB-graft-β-CD/Zn2+ complex via the inclusion with Ad-COONa also endowed the resulting fluorescent nanoparticles with a further protein-binding function. Upon gradual addition of the fluorescent nanoparticle aqueous dispersion to the BSA buffer solution, the fluorescence intensity at 349 nm corresponding to BSA decreased, while the fluorescence intensity of the nanoparticle at 429 nm increased through an isoemissive point at 388 nm, indicating the occurrence of efficient fluorescence resonance energy transfer (FRET) between the fluorescent nanoparticles and protein. This novel protein sensing capability would give the fluorescent nanoparticles great potential in biotechnology.
    Polym. Chem. 02/2013; 4(5):1557-1564.
  • Naiyu Xiao, Hui Liang, Jiang Lu
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    ABSTRACT: Well-defined aldehyde-functionalized glycopolymers were synthesized via reversible addition-fragmentation chain transfer (RAFT) copolymerization of 1,2:3,4-di-O-isopropylidene-6-O-(2′-formyl-4′-vinylphenyl)-D-galactopyranose (IVDG) and 5,6-benzo-2-methylene-1,3-dioxepane (BMDO) using dicumyl peroxide as the initiator and 1-phenylethyl phenyldithioacetate as the RAFT agent at 130 °C in anisole. The resulting copolymers were found to be hydrolytically degradable due to their main-chain polyester structures. Removal of the protective isopropylidene groups from the sugar residues resulted in a novel amphiphilic copolymer with low cytotoxicity as confirmed by MTT assay against L929cells. The deprotected copolymer could conjugate anticancer drugDOXvia an acid-labile Schiff base linkage to form DOX-loaded micelles in a high drug loading level (14 wt%) with pendent galactose moieties covering the surface. The size of the DOX-conjugated polymeric micelle was determined to be about 125 nm by dynamic light scattering. The in vitro release studies demonstrated that the release of DOX from the micelles manifested a strong dependence on the environment pH due to the acid-cleavable Schiff base linkage between the DOX and micelles. The DOX release was significantly faster at pH 5.0 compared to pH 7.4.
    Soft Matter 11/2011; 7(22):10834-10840. · 4.15 Impact Factor
  • Kunmin Yang, Hui Liang, Jiang Lu
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    ABSTRACT: A well-defined multifunctional star polymer consisting of reactive and thermoresponsive poly(N-isopropylacrylamide-co-acrolein) arms and an aluminum tris(8-hydroxyquinoline) (Alq3)-bearing fluorescently labeled core was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization using the “arm-first” method. Acrolein, a commercially available aldehyde-bearing monomer, was copolymerized with N-isopropylacrylamide (NIPAM) via RAFT technique in a controlled way to give well-defined linear trithiocarbonate terminated poly(NIPAM-co-acrolein) macro-RAFT agent. The preformed linear macro-RAFT agent was then cross-linked by a tri-vinyl Alq3-containing cross-linker (Alq3 cross-linker) in conjunction with N,N′-methylenebisacrylamide to give the desired reactive, thermoresponsive, and fluorescently labeled star polymer. The resultant star polymer exhibits a lower critical solution temperature at 29.8 °C in water, and displays intense greenish-yellow fluorescence with maximum emission peak around 520 nm in both organic solvent (i.e., THF) and water. Moreover, the highly reactive aldehyde functions in the arms of the star polymer could provide the key intermediates to conjugate biomolecules, and the conjugation with an aminooxy-functionalized BSA model protein was also demonstrated as an example of how the novel star polymer can be utilized to conjugate bioactive molecules, constructing fluorescently labeled “smart” polymer-protein conjugates.
    Journal of Materials Chemistry 07/2011; 21(28):10390-10398. · 6.63 Impact Factor
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    ABSTRACT: The effects of local dipole on the chiroptical properties of chiral conjugated oligomers were investigated by comparative studies on two analogous chiral oligo(phenyleneethynylene)s: Myr-OPE-Br and Myr-OPE. Myr-OPE-Br carries local dipoles introduced by electron-accepting Br-groups and electron-donating chiral alkoxy-groups, while Myr-OPE only carries chiral alkoxy groups. The DSC thermogram of Myr-OPE-Br showed a glass transition at ∼80°C and a cold crystallization centered at 120°C, while Myr-OPE only showed a glass transition at ∼90°C. Thermal annealing treatment showed significant effects on the absorption and CD spectra of spin-coated film of Myr-OPE-Br: with annealing above 100°C, the absorption maximum exhibited an obvious red shift; the absorption bands displayed well-resolved vibronic structures; the CD spectrum was inversed compared to those with no annealing or annealing at 80°C; and the gabs value of the annealed film increased with increasing annealing temperature and time. After annealing at 140°C for 1h, a maximum gabs value above 0.117 was observed for Myr-OPE-Br film. While for Myr-OPE, the thermal annealing treatment showed no obvious effect on both the absorption and CD spectra. The CD spectra of both the as-coated film and annealed film of Myr-OPE showed no obvious Cotton effect. The observed large g values as well as the thermochromic changes in the absorption and CD spectra of annealed Myr-OPE-Br films were attributed to the presence of local dipoles.
    Synthetic Metals 06/2011; 161(11):1058-1062. · 2.11 Impact Factor
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    ABSTRACT: A facile synthetic pathway to miktoarm star copolymers with multiple arms has been developed by combining reversible addition–fragmentation chain transfer (RAFT) arm-first technique and aldehyde–aminooxy “click” coupling reaction. Star polystyrene (PS) with aldehyde functionalized core was initially prepared by RAFT arm-first technique via crosslinking of the preformed linear macro-RAFT agents using a newly designed aldehyde-containing divinyl compound 6,6′-(ethane-1,2-diylbis(oxy))bis(3-vinylbenzaldehyde) (EVBA). It was then used as a multifunctional coupling agent for the subsequent formation of the second generation poly(ethylene glycol) (PEG) arms via the click coupling reaction between its aldehyde groups and aminooxy-terminated PEGs. The possible formation of PS-PEG miktoarm star copolymer with Janus-like segregated structure in cyclohexanone was also investigated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3323–3330, 2010
    Journal of Polymer Science Part A Polymer Chemistry 06/2010; 48(15):3323 - 3330. · 3.54 Impact Factor
  • Zhaomian Wu, Hui Liang, Jiang Lu
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    ABSTRACT: A facile synthetic pathway to poly(N-isopropylacrylamide) (PNIPAM)−poly(ethylene glycol) (PEG) miktoarm star copolymers with multiple arms has been developed by combining reversible addition−fragmentation chain transfer (RAFT) polymerization and aldehyde−aminooxy “click” coupling reaction. Star PNIPAM with aldehyde functionalized core was initially prepared by the RAFT arm-first technique via cross-linking of the preformed linear macro-RAFT agents using a newly designed aldehyde-containing divinyl compound 6,6′-(ethane-1,2-diylbis(oxy))bis(3-vinylbenzaldehyde) (EVBA). It was then used as a multifunctional coupling agent for the subsequent formation of the second-generation PEG arms via the click coupling reaction between its aldehyde groups and aminooxy-terminated PEGs. The thermoresponsive micellization behavior of PNIPAM−PEG miktoarm star copolymer with different PEG arm numbers in water was also investigated. Opportunities are open for thermoinduced intermolecular or intramolecular micellization of PNIPAM−PEG miktoarm star copolymers via controlling the content ratio of PNIPAM and PEG, forming multimolecular micelles and unimolecular micelles, respectively.
    Macromolecules. 05/2010; 43(13).
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    ABSTRACT: Topographical features, including fiber dimensions and pattern, are important aspects in developing fibrous scaffolds for tissue engineering. In this study aligned poly(l-lactide) (PLLA) fibers with diameters of 307+/-47, 500+/-53, 679+/-72 and 917+/-84 nm and random fibers with diameters of 327+/-40, 545+/-54, 746+/-82 and 1150+/-109 nm were obtained by optimizing the electrospinning parameters. We cultured neonatal mouse cerebellum C17.2 cells on the PLLA fibers. These neural stem cells (NSCs) exhibited significantly different growth and differentiation depending upon fiber dimension and pattern. On aligned fibers cell viability and proliferation was best on 500 nm fibers, and reduced on smaller or larger fibers. However, on random fibers cell viability and proliferation was best with the smallest (350 nm) and largest (1150 nm) diameter fibers. Polarized and elongated cells were orientated along the fiber direction on the aligned fibers, with focal contacts bridging the cell body and aligned fibers. Cells of spindle and polygonal morphologies were randomly distributed on the random fibers, with no focal contacts observed. Moreover, longer neurites were obtained on the aligned fibers than random fibers within the same diameter range. Thus, the surface topographic morphologies of fibrous scaffolds, including fiber pattern, dimensions and mesh size, play roles in regulating the viability, proliferation and neurite outgrowth of NSCs. Nevertheless, our results indicated that aligned 500 nm fiber are most promising for fine tuning the design of a nerve scaffold.
    Acta biomaterialia 02/2010; 6(8):2960-9. · 5.68 Impact Factor
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    ABSTRACT: Well-defined amphiphilic block copolymers consisting of a hydrophilic poly(ethylene oxide) (PEO) block linked to a hydrophobic block with reactive aldehyde and redox-active ferrocenegroups was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of 2-formal-4-vinylphenylferrocenecarboxylate (FVFC) using a monomethoxy-terminated PEO-based macro-chain transfer agent. These amphiphilic block copolymers self-assembled into spherical micelles in aqueous solution, and their size clearly depended on the molecular weight of the PFVFC hydrophobic block, which could be controlled directly via the aforementioned RAFT polymerization. The availability of the synthesized amphiphilic block copolymer to conjugate bioactive molecules was confirmed via the reaction with an aminooxy model drugO-benzylhydroxylamine (BHA). The oxidation peak potential of the conjugates in cyclic voltammetry depended on the amount of the conjugated BHA, allowing one to quantify the degree of the conjugation simply by electrochemical measurement. Also, water-soluble (NH4)Ce(NO3)6 and NaHSO3 were used as the oxidizing and reducing agents, respectively, to explore the redox-controlled responsive behaviors of BHA conjugated PEO-b-PFVFC micelles using UV-vis spectroscopy, scanning electron microscopy and dynamic light scattering. This redox-responsive behavior would provide a prerequisite for redox-controlled release of encapsulants.
    Journal of Materials Chemistry 01/2010; · 6.63 Impact Factor
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    ABSTRACT: A reversible addition-fragmentation chain transfer (RAFT) agent was directly anchored onto Fe3O4 nanoparticles in a simple procedure using a ligand exchange reaction of S-1-dodecyl-S′-(α,α′-dimethyl-α″-acetic acid)trithiocarbonate with oleic acid initially present on the surface of pristine Fe3O4 nanoparticles. The RAFT agent-functionalized Fe3O4 nanoparticles were then used for the surface-initiated RAFT copolymerization of N-isopropylacrylamide and acrolein to fabricate structurally well-defined hybrid nanoparticles with reactive and thermoresponsive poly(N-isopropylacrylamide-co-acrolein) shell and magnetic Fe3O4 core. Evidence of a well-controlled surface-initiated RAFT copolymerization was gained from a linear increase of number-average molecular weight with overall monomer conversions and relatively narrow molecular weight distributions of the copolymers grown from the nanoparticles. The resulting novel magnetic, reactive, and thermoresponsive core-shell nanoparticles exhibited temperature-trigged magnetic separation behavior and high ability to immobilize model protein BSA. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 542–550, 2010
    Journal of Polymer Science Part A Polymer Chemistry 12/2009; 48(3):542 - 550. · 3.54 Impact Factor
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    ABSTRACT: Living/controlled polymerization of 2-((8-hydroxyquinolin-5-yl)methoxy)ethyl methacrylate (HQHEMA) was achieved by reversible addition−fragmentation chain transfer (RAFT) polymerization with 2-cyanoprop-2-yl dithiobenzoate (CPDB) as the RAFT agent and 2,2′-azoisobutyronitrile (AIBN) as the initiator in THF at 65 °C. The resulting PHQHEMA was used as a macro-RAFT agent in the RAFT polymerization of styrene to give diblock copolymer PHQHEMA-b-PS. The obtained diblock copolymer could self-assemble into nanosized micelles in a solvent mixture of toluene (Tol, selective solvent for block of polystyrene, nonsolvent for block of PHQHEMA) and THF (common solvent). The diameter and shape of the micelles were dependent on the molecular weights of the copolymers and the solvent compositions. The diameter of micelle increased with increasing molecular weight of the block copolymers and Tol content in the solvent mixture. Spherical micelles with a diameter in the range between 30 and 60 nm were formed under a Tol/THF ratio of 5:5 or 6:4, but, when the Tol/THF ratio increased to 8:2, the micelles changed from spherical structures to wormlike structures. Then, the formed micelles were used as nanoreactors to complex with triethylaluminum to give luminescent micelles with ionic cross-linking cores containing tris(8-hydroquinolinato)aluminum (Alq3). The luminescent micelles could be redispersed in the solvents of polystyrene after drying. The emission spectra showed that the Alq3 moieties acted as independent chromophores in the micelles.
    Macromolecules 02/2009; 42(4). · 5.93 Impact Factor
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    ABSTRACT: By the method of injection molding combined with thermally induced phase separation (TIPS), a novel nerve conduit with a plurality of channels and macro-/microporous architecture was fabricated using poly (lactide-co-glycolide) (PLGA, 75:25; Mn=1.22x10(5)). The diameter of the conduits and the number of channels could be regulated by changing the parameters of the mold, and the porosity of the conduit was as high as 95.4%. Meanwhile, the hierarchical pore architecture of the walls could be controlled through varying the solution concentration and the contents of porogen. The degradation study in vitro showed that 7-channel conduit could hold its apparent geometry for about 12 weeks in phosphate buffer solution (PBS) at 37degreesC, and the pH values of the degradation solution were detected in the range 4.1-4.5. The influences of the conduit architecture on the cell attachment, spreading, and proliferation were evaluated by culturing rat mesenchymal stem cells alone or together with Schwann cells in vitro. The implantation of the PLGA conduit in the spinal cord showed that it had good biocompatibility, and no obvious inflammatory response was detected. Therefore, the results implied that these PLGA multiple-channel nerve conduits have the potential use for spinal cord injury.
    Tissue Engineering Part C Methods 02/2009; 15(2):243-55. · 4.64 Impact Factor
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    ABSTRACT: Chemical guiding cues are being exploited to stimulate neuron adhesion and neurite outgrowth. In this study, an amino-functioned PLLA, lysine-capped PLLA [K-(CH2)n-PLLA (n = 2, 5, 8)], was synthesized with different length of linking spaces between lysine molecule and PLLA backbone. Drop-cast films were fabricated from K-(CH2)n-PLLA/PLLA blends (10/90, w/w) and amino groups were detected on the surfaces of the resultant films. More amine groups were detected on the surface and the hydrophilicity of the films was obviously improved by annealing the films in water. The representative atomic force microscopy (AFM) images indicated that incorporation of lysine-capped PLLA into PLLA matrix increased the roughness of the films and resulted in a phase separation with distinct two nano-domains which may correspond to the hydrophilic and hydrophobic domains. Furthermore, the laminin-derived peptides, CYIGSR (Cys-Tyr-Ile-Gly-Ser-Arg) and CSIKVAV (Cys-Ser-Ile-Lys-Val-Ala-Val), were jointly tethered to the amine groups of lysine-capped PLLA by a linking reagent sulfo-succinimidyl 4-(N-maleimidomethyl) cyclohexane-1-carboxylate (Sulfo-SMCC). The neonatal mouse cerebellum C17.2 stem cells were seeded on the peptides-grafted K-(CH2)n-PLLA/PLLA (n = 2, 5, 8) films and pure PLLA films were used as controls. Improved viability and longer neurites were obtained on the peptide-grafted films than PLLA film over the cultivation period, especially for K-(CH2)5-PLLA/PLLA, which had the highest peptide density of 0.28 ± 0.03 μg/cm2. This study highlights the potential of using the lysine-cappeded PLLA with laminin-derived peptides for promoting nerve regeneration.
    Biomaterials 01/2009; · 8.31 Impact Factor
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    ABSTRACT: Nano-fibrous scaffolds which could potentially mimic the architecture of extracellular matrix (ECM) have been considered a good candidate matrix for cell delivery in tissue engineering applications. In the present study, a semicrystalline diblock copolymer, poly(epsilon-caprolactone)-block-poly(L-lactide) (PCL-b-PLLA), was synthesized and utilized to fabricate nano-fibrous scaffolds via a thermally induced phase separation process. Uniform nano-fibrous networks were created by quenching a PCL-b-PLLA/THF homogenous solution to -20 degrees C or below, followed by further gelation for 2 hours due to the presence of PLLA and PCL microcrystals. However, knot-like structures as well as continuously smooth pellicles appeared among the nano-fibrous network with increasing gelation temperature. DSC analysis indicated that the crystallization of PCL segments was interrupted by rigid PLLA segments, resulting in an amorphous phase at high gelation temperatures. Combining TIPS (thermally induced phase separation) with salt-leaching methods, nano-fibrous architecture and interconnected pore structures (144+/-36 mm in diameter) with a high porosity were created for in vitro culture of chondrocytes. Specific surface area and protein adsorption on the surface of the nano-fibrous scaffold were three times higher than on the surface of the solid-walled scaffold. Chondrocytes cultured on the nano-fibrous scaffold exhibited a spherical condrocyte-like phenotype and secreted more cartilage-like extracellular matrix (ECM) than those cultured on the solid-walled scaffold. Moreover, the protein and DNA contents of cells cultured on the nano-fibrous scaffold were 1.2-1.4 times higher than those on the solid-walled scaffold. Higher expression levels of collagen II and aggrecan mRNA were induced on the nano-fibrous scaffold compared to on the solid-walled scaffold. These findings demonstrated that scaffolds with a nano-fibrous architecture could serve as superior scaffolds for cartilage tissue engineering.
    European cells & materials 01/2009; 18:63-74. · 4.56 Impact Factor
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    ABSTRACT: A new N,N,O-tridentate chelate ligand, namely 2-(benzimidazol-2-yl)-8-octyloxyquinoline, has been synthesized with 8-hydroxyquinadine and o-phenylenediamine as the starting materials. The obtained ligand reacts with diethylzinc to give a neutral Zn(II) complex. The molecular structure of the complex has been determined by X-ray crystallography. The preliminary investigations on the thermal, electrochemical and luminescent properties of the complex are presented.
    Inorganic Chemistry Communications 06/2008; 11(6):662–664. · 2.02 Impact Factor
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    ABSTRACT: Chiral poly(p-phenylenevinylene-alt-m-phenylenevinylene)s bearing (−)-trans-myrtanoxyl groups on the p-phenylene rings were synthesized by Wittig's reaction and Heck's reaction, respectively, namely Myr-PMPV-w and Myr-PMPV-h correspondingly. The chiroptical properties of the polymers were investigated in chlorobenzene solution by circular dichroism. The results showed that both Myr-PMPV-w and Myr-PMPV-h showed no Cotton effect due to their irregular molecular structure. By the treatment with I2, most of the cis-vinylene linkages in Myr-PMPV-w were converted to trans-vinylenes, consequently, the structure of Myr-PMPV-w became much more regular, and the resulting polymer (iso-Myr-PMPV-w) showed strong bisignate Cotton effects in the π–π* transition. Compared to its analogous poly(p-phenylenevinylene) (PPV) (iso-Myr-PPV-w), iso-Myr-PMPV-w showed much stronger Cotton effect, its maximum g value was about one order of magnitude higher than that of iso-Myr-PPV-w under the same conditions. With increasing concentration and decreasing temperature, the gmax value of iso-Myr-PMPV-w increased, and the maximum absorption was slightly blue-shifted, but the shape and range of absorption curves did not changed significantly, and no clear isosbestic point could be observed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3336–3343, 2008
    Journal of Polymer Science Part A Polymer Chemistry 05/2008; 46(10). · 3.54 Impact Factor
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    ABSTRACT: A new aldehyde-functionalized glycomonomer, 1,2:3,4-di-O-isopropylidene-6-O-(2′- formyl-4′-vinylphenyl)-d-galactopyranose (IVDG), was designed and prepared. The “living”/controlled radical polymerization of IVDG was successfully achieved using 2,2′-azobis(isobutyronitrile) as the initiator and 1-phenylethyl dithiobenzoate as the reversible addition−fragmentation chain transfer (RAFT) agent at 60 °C in tetrahydrofuran. The polymerization followed first-order kinetics, the number-average molecular weight of the obtained polymers increased in direct proportion to the monomer conversion, and the molecular weight distribution was narrow (polydispersity index <1.1). Removal of protective isopropylidene groups from the sugar residue in polyIVDG was carried out quantitatively using 88% formic acid at room temperature, yielding a novel amphiphilic polymer containing both galactopyranose and aldehyde functionalities. These amphiphilic polymers self-assembled into well-defined aldehyde-bearing polymeric micelles in aqueous solution without recourse to any surfactant. The size of the micelles increased almost linearly with the molecular weight of polyIVDG precursor, which could be controlled directly via the aforementioned RAFT polymerization process. Protein-bioconjugated nanoparticles were also successfully prepared by the immobilization of bovine serum albumin (as a model protein) onto the aldehyde-functionalized micelles.
    Macromolecules. 03/2008; 41(7).
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    ABSTRACT: A series of easily accessible and stable Schiff-base nickel complexes (complex 1–4) in conjunction with methylaluminoxane (MAO) were employed for the synthesis of relatively high molecular weight β-pinene polymers at high temperature with high productivity. The ligand structure of the complex had a substantial effect on the polymerization in terms of the productivity and the molecular weight. With complex 4 in the presence of MAO, high molecular weight polymers of β-pinene (Mn ∼ 10,900) were obtained at 40 °C with an extremely high productivity up to 1.25 × 107 g polyβ-pinene/mol of Ni. 1H NMR analyses showed that the obtained β-pinene polymer was structurally identical to that formed by conventional cationic Lewis acid initiators. The polymerization was presumably initiated by the nickel cation formed by the reaction of the schiff-base nickel complex and MAO, while the propagation proceeded in a manner typical for a conventional carbocationic polymerization process. Direct evidence for the carbocationic polymerization was offered by the fact that quenching of the polymerization with methanol at a low monomer conversion resulted in incorporation of a methoxyl end group into the polymer chain. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3739–3746, 2007
    Journal of Polymer Science Part A Polymer Chemistry 07/2007; 45(16):3739 - 3746. · 3.54 Impact Factor
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    ABSTRACT: A new monomer, 2-formal-4-vinylphenyl ferrocenecarboxylate (FVFC), containing both aldehyde and ferrocene functional groups was designed and prepared by the reaction of ferrocenecarboxylic acid chloride with 2-hydroxy-5-vinylbenzaldehyde. The controlled radical polymerization of FVFC was achieved using 2,2‘-azobis(isobutyronitrile) (AIBN) as the initiator and 2-cyanopropyl-2-yl dithiobenzoate (CPDB) as the reversible addition−fragmentation chain transfer (RAFT) agent at 60 °C in tetrahydrofuran (THF). The polymerization nearly followed first-order kinetics, the number-average molecular weight of the obtained polymers increased almost in direct proportion to the monomer conversion, and the molecular weight distribution was narrow (polydispersity index < 1.2). The chain and terminal structures of the obtained polyFVFC were confirmed by 1H NMR and matrix-assisted laser desorption−ionization time-of-flight mass spectrometry analysis. The obtained polyFVFC can be employed as a macro-RAFT agent for styrene polymerization, resulting in polyFVFC-b-polystyrene.
    Macromolecules. 02/2007; 40(6).

Publication Stats

147 Citations
83.82 Total Impact Points

Institutions

  • 2004–2014
    • Sun Yat-Sen University
      • • Department of Chemical Engineering
      • • Department of Polymer and Material Sciences
      Shengcheng, Guangdong, China
  • 2010
    • National University of Singapore
      • Department of Bioengineering
      Singapore, Singapore
  • 2000–2004
    • Zhongshan University
      Shengcheng, Guangdong, China