Co-reporter:Wan-chu Wei;Shuo Feng;Cai-xia Zheng;Guo-dong Liang
Chinese Journal of Polymer Science 2017 Volume 35( Issue 3) pp:400-406
Publication Date(Web):2017 March
DOI:10.1007/s10118-017-1884-y
The fluorescently labelled polymers including pyrene-labelled polystyrene (PyPS) and pyrene-labelled poly(methyl methacrylate) (PyPMMA) with narrow molecular weight distributions were synthesized by the atom transfer radical copolymerization (ATRCP) of styrene or methyl methacrylate with 1-pyrenemethyl methacrylate (PyMMA). The ultrathin PyPS and PyPMMA films with the thickness ranging from 30 nm to 400 nm supported on the quartz slides were prepared by spin-coating. The fluorescent quantum yield (QY) of the pyrene probe in the ultrathin polymer films was investigated by the photoluminescence spectrometer using an integrating sphere detector. The QY decreased with the reduction of film thickness in the sub-200 nm range.
Co-reporter:Hua-qing Liang;Qi-hua Zhou;Yong-jiang Long
Chinese Journal of Polymer Science 2017 Volume 35( Issue 7) pp:866-873
Publication Date(Web):26 May 2017
DOI:10.1007/s10118-017-1933-6
Herein, we demonstrate the synthesis of a well-defined diblock copolymer consisting of isotactic polystyrene (iPS) and linear polyethylene, isotactic polystyrene-block-polyethylene (iPS-b-PE), by the combination of sequential monomer addition and hydrogenation. Isospecific living polymerization of styrene and living trans-1,4-polymerization of 1,3-butadiene were catalyzed by 1,4-dithiabutandiyl-2,2′-bis(6-cumenyl-4-methylphenoxy) titanium dichloride (complex 1) activated by triisobutyl aluminum modified methylaluminoxane (MMAO) at room temperature to provide highly isotactic polystyrene (iPS) and 1,4-trans-polybutadiene (1,4-trans-PBD) with narrow molecular weight distribution. Furthermore, the iPS-b-1,4-trans-PBD was synthesized via sequential monomer addition in the presence of complex 1 and MMAO. The hydrogenation of the 1,4-trans-PBD block was promoted by RuCl2(PPh3)3 used as a catalyst to produce iPS-b-PE.
Co-reporter:QiHua Zhou;HuaQing Liang;WanChu Wei;ChunFeng Meng;YongJiang Long
RSC Advances (2011-Present) 2017 vol. 7(Issue 32) pp:19885-19893
Publication Date(Web):2017/03/31
DOI:10.1039/C7RA01450C
A series of isotactic diblock copolymers of polystyrene-block-poly(p-tert-butyldimethylsilyloxystyrene) (iPS-b-iP(p-TBDMSOS)) were successfully synthesized using living coordination polymerization techniques with a kind of titanium dichloro complex containing a 1,4-dithiabutandiyl-linked [OSSO]-type bis(6-cumyl-4-methyl phenolato) ligand (complex 1) activated by methylaluminoxane (MAO) as a catalyst. Nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), infrared spectroscopy (IR), and differential scanning calorimetry (DSC) were used to characterize the copolymers. iPS-b-iP(p-TBDMSOS) had a higher molecular weight than that of the iPS prepolymer, and a narrow molecular weight distribution below 1.35. The diblock copolymers displayed two glass transition temperatures (Tg) at ∼97 and ∼117 °C, originating from iPS and iP(p-TBDMSOS) blocks, respectively. Furthermore, a novel well-defined amphiphilic diblock copolymer consisting of iPS (nonpolar block) and isotactic poly(p-hydroxystyrene) (iP(p-HOS), polar block), was achieved through hydrolysis of iP(p-TBDMSOS) block of iPS-b-iP(p-TBDMSOS) in the presence of hydrochloric acid. The obtained amphiphilic diblock copolymers self-assembled into spherical micelles with size of approximately 70 nm in methanol.
Co-reporter:WanChu Wei;Shuo Feng;QiHua Zhou;HuaQing Liang
Journal of Polymer Research 2017 Volume 24( Issue 3) pp:
Publication Date(Web):2017 March
DOI:10.1007/s10965-017-1199-2
In the present study, polystyrene (PS) nanowires in aqueous dispersion with a diameter ranging from 120 to 300 nm are prepared via electrospun and dispersed in water. Relatively, PS nanowires confined in anodic aluminum oxide (AAO) template are prepared through drawing PS flow into the tube of AAO template. Scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) are used to characterize the size of the resultant nanowires and ensure the successful preparation of nanowires. Moreover, the glass transition and physical aging behaviors of the PS nanowires in aqueous dispersion and confined in AAO template are investigated by differential scanning calorimetry (DSC). The PS nanowires in aqueous dispersion and confined in AAO template exhibit different glass transition and physical aging behaviors.
Co-reporter:Guodong Liang, Jialong Wu, Haiyang Gao, Qing Wu, Jiang Lu, Fangming Zhu, and Ben Zhong Tang
ACS Macro Letters 2016 Volume 5(Issue 8) pp:909
Publication Date(Web):July 15, 2016
DOI:10.1021/acsmacrolett.6b00453
Memory polymers capable of remembering their shape or thermal history have attracted increasing interest due to their potential applications in smart and medical devices. Memory polymers established are mechanically based, which suffer from some inherent limitations such as low sensitivity and bulky size. Here, we develop a general platform for sensitive memory polymers. Incorporating crystallizable polymers with solid-state fluorescent dyes results in crystallizable fluorescent polymers. Such polymers show remarkably temperature-dependent fluorescence emission. Interestingly, fluorescence of the polymers shows a hysteresis between heating and subsequent cooling scans, which offers them a valuable thermally stimulated recording function. Both off–on and on–off recording functions can be achieved. Characters recorded on the polymer films can be erased and rewritten. Moreover, thermal history subjected to the polymers can be memorized and retrieved by measuring fluorescence intensity. With the merit of easy synthesis, recording function, remarkably thermoresponsive fluorescence with memory function, superior flexibility, and biocompatibility inherited from polymers, crystallizable fluorescent polymers offer a general platform for memory fluorescent polymers that are potentially useful for biosensing, recording materials, and smart devices.
Co-reporter:Qi-hua Zhou;Zhi-yun Li;Hua-qing Liang
Chinese Journal of Polymer Science 2015 Volume 33( Issue 4) pp:646-651
Publication Date(Web):2015 April
DOI:10.1007/s10118-015-1615-1
Herein we demonstrate crystallization-driven self-assembly of isotactic polystyrene (iPS) with high isotacticity and narrow molecular weight distribution and crystallization-induced switching of the morphology of iPS aggregates in N, N-dimethylformamide (DMF). The formation and morphology switching of the self-assembled aggregates of iPS are investigated by means of dynamic light scattering (DLS), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WXRD). The results reveal that cooling DMF solution of iPS promotes iPS chains to self-assemble into spherical aggregates with a gelled core cross-linked by microcrystals, which is surrounded by solvent-swollen corona. Furthermore, crystallization induces the deformation of iPS aggregates from spherical to plate-like or nest-like.
Co-reporter:BiYun Mai, Ran Liu, ZhiYun Li, Shuo Feng, Qing Wu, HaiYang Gao, GuoDong Liang, FangMing Zhu
Polymer 2015 Volume 57() pp:125-131
Publication Date(Web):28 January 2015
DOI:10.1016/j.polymer.2014.12.017
Co-reporter:Wan-Chu Wei;Shuo Feng;Cai-Xia Zheng;Guo-Dong Liang
Journal of Polymer Research 2015 Volume 22( Issue 11) pp:
Publication Date(Web):2015 November
DOI:10.1007/s10965-015-0855-7
Amphiphilic fluorescent diblock copolymers containing a pyrene-labelled polystyrene (PyPS) block, PyPS-block-poly(acrylic acid) (PyPS-b-PAA) and PyPS-block-poly(ethylene oxide) (PyPS-b-PEO) were synthesized by atom transfer radical polymerization (ATRP). All resultant diblock copolymers and intermediates were characterized by nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC). PyPS-b-PAA in water and PyPS-b-PEO in water or ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide ([EMIM][TFSI]) can self-assemble into spherical nanomicelles with diameters less than 100 nm. Glass transition and fluorescent quantum yield of the core-forming PyPS block confined in the self-assembled spherical nanomicelles were investigated by fluorescence spectroscopy. A dramatic reduction of glass transition temperature (Tg) of the PyPS block within PyPS-b-PEO nanomicelles was observed relative to PS or PyPS bulk. However, in aqueous dispersions, the PyPS block within PyPS-b-PAA nanomicelles exhibited an analogous Tg near to PS or PyPS bulk. Moreover, the fluorescent quantum yield of the PyPS block within the self-assembled nanomicelles in aqueous dispersions is much higher than that of PyPS-b-PEO in toluene solution as well as its bulk.
Co-reporter:Shuo Feng, Yuenan Chen, Biyun Mai, Wanchu Wei, Caixia Zheng, Qing Wu, GuoDong Liang, HaiYang Gao and FangMing Zhu
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 30) pp:15941-15947
Publication Date(Web):18 Jun 2014
DOI:10.1039/C4CP01849D
Surfactant-free nanospheres and latex nanospheres of poly(methyl methacrylate) (PMMA) with diameter ranging from 20 to 220 nm are prepared by atom transfer radical polymerization (ATRP) in microemulsions and subsequent dialysis against deionized water. The glass transitions of these PMMA nanospheres are characterized using nano differential scanning calorimetry (nano-DSC) in aqueous dispersions. The glass transition temperature (Tg) of the surfactant-free PMMA nanospheres and nonionic PMMA latex nanospheres with diameters below 150 nm is less than that of the PMMA bulk, and Tg decreases with the decrease of the diameter. In contrast, Tg of the anionic PMMA latex nanospheres is size-independent and is near to that of the PMMA bulk. The influence of the environment surrounding the PMMA nanospheres on glass transitions as well as comparisons to our prior studies with polystyrene (PS) nanospheres in aqueous dispersions are discussed.
Co-reporter:ZhiYun Li, Ran Liu, BiYun Mai, Shuo Feng, Qing Wu, GuoDong Liang, HaiYang Gao and FangMing Zhu
Polymer Chemistry 2013 vol. 4(Issue 4) pp:954-960
Publication Date(Web):12 Oct 2012
DOI:10.1039/C2PY20814H
Isotactic polystyrene-block-poly(ethylene glycol) (iPS-b-PEG) was synthesized via a thiol–ene click coupling reaction of vinyl-terminated isotactic polystyrene (iPS–) with thiol-terminated poly(ethylene glycol) (PEG-SH). iPS– was prepared by the extremely highly isospecific polymerization of styrene with 1,4-dithiabutandiyl-2,2′-bis(6-tertbutyl-4-methylphenoxy) titanium dichloride and methylaluminoxane (MAO) in the presence of 1,7-octadiene as a chain transfer agent. PEG-SH was synthesized by the direct esterification of hydroxyl-terminated PEG (PEG-OH) with 3-mercaptopropionic acid using HfCl4·2THF as a catalyst. The behavior and micelle morphology of the crystallization-driven self-assembly of iPS-b-PEG in N,N-dimethylformamide (DMF) were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic light scattering (DLS), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The results revealed that the crystallinity of the iPS blocks in the micelle cores was increased with increasing the storage time of the micelle solution at room temperature, and the increase of crystallinity led to the transition from spherical to petal-like micelles. With time these petal-like micelles could self-associate into flower-like aggregates. Moreover, when the newly prepared micelle DMF solution of iPS-b-PEG was dialyzed against deionized water, bowl-like micelles were formed due to the diffusion of DMF from the iPS cores into the aqueous phase.
Co-reporter:Shuo Feng, ZhiYun Li, Ran Liu, BiYun Mai, Qing Wu, GuoDong Liang, HaiYang Gao and FangMing Zhu
Soft Matter 2013 vol. 9(Issue 18) pp:4614-4620
Publication Date(Web):21 Feb 2013
DOI:10.1039/C3SM27576K
Two aqueous dispersions of anionic and nonionic polystyrene (PS) latex nanospheres were prepared via activators generated by electron transfer (AGET) atom transfer radical polymerization (ATRP) and reverse ATRP in microemulsions using sodium dodecyl benzene sulfonate (SDBS) and polyoxyethylene (20) oleyl ether (Brij 98) as surfactant, respectively. Moreover, the third aqueous dispersion of surfactant-free PS nanospheres was obtained by the dialysis of a PS microemulsion against deionized water. The molecular weight distributions (Mw/Mn) of the resultant PS with controlled-molecular weight were less than 1.7. We investigated the glass transition of these PS nanospheres in different aqueous dispersions by nano-DSC. We observed an apparent size-dependent glass transition on the surfactant-free PS nanospheres and nonionic PS latex nanospheres, and that the glass transition temperature (Tg) decreases with the reduction of size for PS nanospheres. However, the anionic PS latex nanospheres show an unambiguous glass transition near to the bulk PS. These results suggest that the effects of size and interface on glass transition may become significant as the diameter of the polymer nanospheres is decreased to less than 100 nm.
Co-reporter:Ran Liu;Zhi Yun Li;Wan Juan Wang;Dan Yuan;Chun Feng Meng;Qing Wu;Fang Ming Zhu
Journal of Applied Polymer Science 2013 Volume 129( Issue 4) pp:2216-2223
Publication Date(Web):
DOI:10.1002/app.38935
Abstract
We report on the synthesis and self-assembly in water of well-defined amphiphilic star-block copolymers with a linear crystalline polyethylene (PE) segment and two or three poly(ethylene glycol) (PEG) segments as the building blocks. Initially, alkynyl-terminated PE (PE-) is synthesized via esterification of pentynoic acid with hydroxyl-terminated PE, which is prepared using chain shuttling ethylene polymerization with 2,6-bis[1-(2,6-dimethylphenyl) imino ethyl] pyridine iron (II) dichloride/methylaluminoxane/diethyl zinc and subsequent in situ oxidation with oxygen. Then diazido- and triazido-terminated PE (PE-(N3)2 and PE-(N3)3) are obtained by the click reactions between PE- and coupling agents containing triazido or tetraazido, respectively. Finally, the three-arm and four-arm star-block copolymers, PE-b-(PEG)2 and PE-b-(PEG)3, are prepared by click reactions between PE-(N3)2 or PE-(N3)3 and alkynyl-terminated PEG. The self-assembly of the resultant amphiphilic star-block copolymers in water was investigated by dynamic light scattering, transmission electron microscopy, and atomic force microscopy. It is found that, in water, a solvent selectively good for PEG blocks; these star-block copolymer chains could self-assemble to form platelet-like micelles with insoluble PE blocks as crystalline core and soluble PEG blocks as shell. The confined crystallization of PE blocks in self-assembled structure formed in aqueous solution is investigated by differential scanning calorimetry. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:ZhiYun Li, Ran Liu, BiYun Mai, WanJuan Wang, Qing Wu, GuoDong Liang, HaiYang Gao, FangMing Zhu
Polymer 2013 Volume 54(Issue 6) pp:1663-1670
Publication Date(Web):8 March 2013
DOI:10.1016/j.polymer.2013.01.044
In this paper, the well-defined diblock copolymers consisting a linear polyethylene (LPE) and a poly(ethylene oxide) (PEO), LPE-b-PEO, were synthesized by combining the ethylene living coordination polymerization with fluorinated bis(phenoxyimine) titanium catalyst and the living ring-opening polymerization of ethylene oxide initiated by hydroxyl-terminated polyethylene (LPE–OH) as a macromolecular initiator. We describe two methodologies for the self-assembly of LPE-b-PEO, namely temperature-induced self-assembly and crystallization-driven self-assembly. Transmission electron microscopy (TEM), atomic force microscopy (AFM) and dynamic light scattering (DLS) are employed to characterize the morphology, structure and hydrodynamic radius (Rh) of the self-assembled micelles. LPE-b-PEO is dissolved to form a molecular solution in trichlorobenzene (TCB) at 140 °C, while self-assembly could be driven when the crystallization of LPE blocks is induced by cooling to form diamond-shaped micelles with a mono-layer crystallized LPE lamella core. The resultant diblock copolymers can self-assemble into spherical micelles composed of a molten LPE core and a soluble PEO corona in DMF at 140 °C, that is above the melting temperature (Tm) of the LPE block. As the temperature decrease, the morphology changes from spherical to platelet-like micelle with a double-layer crystallized LPE lamella core sandwiched by solvent-swollen PEO corona. Furthermore, the confined crystallization of LPE block in nanosized self-assembled micelle core is investigated by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXRD).
Co-reporter:Biyun Mai;Zhiyun Li;Ran Liu;Shuo Feng;Qing Wu
Journal of Polymer Research 2013 Volume 20( Issue 11) pp:
Publication Date(Web):2013 November
DOI:10.1007/s10965-013-0299-x
This study demonstrates the self-assembly of crystalline-coil diblock copolymers of poly(ε-caprolactone)-b-poly(ethylene oxide) (PCL-b-PEO) with narrow molecular weight distributions in aqueous solution. The formed spherical micelles with sub-100 nm diameters are composed of a PCL core with low crystallinity and a soluble PEO corona. Isothermal crystallization behavior of the core-forming PCL blocks in nanoscale self-assembled micelles is investigated by nano differential scanning calorimetry (nano-DSC) and transmission electron microscopy (TEM) at different temperatures ranging from 25 to −50 °C. It is found that confined crystallization of the PCL blocks in nanocores only takes place after the micellar aqueous solution turns frozen and gives rise to the in situ formed spherical nanoaggregates consisting of disc-shaped lamellae.
Co-reporter:Yugang Huang, Yonghong Zeng, Jianwen Yang, Zhaohua Zeng, Fangming Zhu and Xudong Chen
Chemical Communications 2011 vol. 47(Issue 26) pp:7509-7511
Publication Date(Web):31 May 2011
DOI:10.1039/C1CC12177D
Rapid and highly efficient side-chain functionalization of polypeptides was achieved via combination of ring-opening polymerization of a new clickable monomer of γ-propargyl-L-glutamateN-carboxyanhydride (PLG-NCA) and thiol-yne photochemistry, which provides a convenient and universal route to prepare diverse polypeptide-based biomimetic hybrid materials.
Co-reporter:Ting Li;Fan Wang Kong;Ran Liu;Zhi Yun Li ;Fang Ming Zhu
Journal of Applied Polymer Science 2011 Volume 119( Issue 1) pp:572-576
Publication Date(Web):
DOI:10.1002/app.32642
Abstract
In this study, we examined various alkylaluminums, including triethylaluminum (TEA), triisobutylaluminum (TIBA), and diethylaluminum chloride (DEAC), as cocatalysts for the activation of ethylene polymerizations in the presence of a fluorinated Fujita group invented titanium (FI-Ti) catalyst, bis[N-(3-tert-butylsalicylidene)-2,3,4,5,6-pentafluoroanilinato] titanium(IV) dichloride (complex 1). DEAC, because of the strong Lewis acidity, was an efficient cocatalyst for activating complex 1 for the ethylene polymerizations, whereas TEA and TIBA as cocatalysts could hardly polymerize ethylene. The effects of the polymerization temperature and Al/Ti molar ratio on the formation of active species, properties, and molecular weight of the resulting polyethylene were investigated. In the complex 1/DEAC catalyst system, the oxidation states of Ti active species were determined by electron paramagnetic resonance. The results demonstrated that Ti(IV) active species were inclined to polymerize ethylene and yielded high-molecular-weight polyethylene. Comparatively, Ti(III) active species resulted from the reduction of Ti(IV) by DEAC and afforded oligomers. Moreover, the bigger steric bulk for the cocatalysts was necessary to achieve ethylene living polymerization with the fluorinated FI-Ti catalyst. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Co-reporter:Ran Liu, Zhiyun Li, Dan Yuan, Chunfeng Meng, Qing Wu, Fangming Zhu
Polymer 2011 Volume 52(Issue 2) pp:356-362
Publication Date(Web):21 January 2011
DOI:10.1016/j.polymer.2010.12.013
We report on the synthesis and self-assembly of a novel well-defined miktoarm star copolymer of (polyethylene)2−(polystyrene)2, (PE)2−(PS)2, with two linear crystalline PE segments and two PS segments as the building blocks based on chain shuttling ethylene polymerization (CSEP), click reaction and atom transfer radical polymerization (ATRP). Initially, alkynyl-terminated PE (PE–) was synthesized via the esterification of pentynoic acid with hydroxyl-terminated PE (PE−OH), which was prepared using CSEP with 2,6-bis[1-(2,6-dimethylphenyl) imino ethyl] pyridine iron (II) dichloride/methylaluminoxane/diethyl zinc and subsequent in situ oxidation with oxygen. (PE)2−(OH)2 was then obtained by the click reaction of PE– with diazido and dihydroxyl containing coupling agent. The two hydroxyl groups in (PE)2−(OH)2 were then converted into bromisobutyrate by esterification. At last, the (PE)2−(PS)2 miktoarm star copolymers were synthesized by ATRP of styrene initiated from (PE)2−Br2 macroinitiator. All the intermediates and final products were characterized by 1H NMR and gel permeation chromatography (GPC). The self-assembly behavior was studied by dynamic light scattering (DLS) and atomic force microscopy (AFM). The crystallization of the (PE)2−(PS)2 miktoarm star copolymers was studied by differential scanning calorimetry (DSC).
Co-reporter:Wanjuan Wang;Ran Liu;Zhiyun Li;Chunfeng Meng;Qing Wu
Macromolecular Chemistry and Physics 2010 Volume 211( Issue 13) pp:1452-1459
Publication Date(Web):
DOI:10.1002/macp.200900614
Co-reporter:Yuan-yuan Wang, Shang-an Lin, Fang-ming Zhu, Hai-yang Gao, Qing Wu
Inorganica Chimica Acta 2009 Volume 362(Issue 1) pp:166-172
Publication Date(Web):1 January 2009
DOI:10.1016/j.ica.2008.03.068
Four phenyl-substituted pyrazolylimine ligands 2-(C3HN2Me2-3,5)(C(Ph)N(4-R2C6H2(R1)2-2,6)) (L1: R1 = iPr, R2 = H; L2: R1 = H, R2 = NO2; L3: R1 = R2 = H; L4: R1 = H, R2 = OCH3) were synthesized. The influences of steric bulk and electronic effect of pyrazolylimine ligands on the structures of their corresponding nickel complexes were investigated. Ligands with more bulky and electron withdrawing substituents on N-phenyl ring produced four-coordinate nickel complexes (2-(C3HN2Me2-3,5))(C(Ph)(4-R2C6H2(R1)2-2,6)NiBr2 (1, R1 = iPr, R2 = H; 2, R1 = H, R2 = NO2)), whereas the ligands with less bulky and electron donating substituents on N-phenyl ring formed bis-pyrazolylimine dinickel tetrahalides (bis-2-(C3HN2Me2-3,5))(C(Ph)N(4-R2C6H2 (R1)2-2,6)Ni2Br4 (3, R1 = R2 = H; 4, R1 = H, R2 = OCH3)) and six-coordinate nickel dihalides (bis-2-(C3HN2Me2-3,5))(C(Ph)N(4-R2C6H2(R1)2-2,6) NiBr2 (5, R1 = R2 = H;6, R1 = H, R2 = OCH3)). The solid-state structures of complexes 1, 4 and 5 have been confirmed by X-ray single-crystal analyses. Activated by methylaluminoxane (MAO), complexes 1, 2, 5 and 6 showed moderate to high activity for ethylene oligomerization, and complex 5 revealed the highest activity up to 8.96 × 105 g oligomer/(mol Ni · h). The proportions of resultant oligomers were mainly C4–C8 and a little C10–C14 determined by gas chromatography/mass spectrometry.The steric bulk and electronic effect of phenyl-substituted pyrazolylimine ligands had a significant influence on the structure of their nickel complexes: ligands with more bulky and electron withdrawing substituents on N-phenyl ring produced four-coordinate nickel complexes, whereas the ligands with less bulky and electron donating substituents on N-phenyl ring formed bis-pyrazolylimine dinickel tetrahalides and six-coordinate bis-pyrazolylimine nickel dihalides. Activated by methylaluminoxane (MAO), the nickel complexes 1, 2, 5 and 6 showed moderate to high activity for ethylene oligomerization.
Co-reporter:Ting Li, Wan Juan Wang, Ran Liu, Wei Hao Liang, Guo Fang Zhao, ZhiYun Li, Qing Wu and Fang Ming Zhu
Macromolecules 2009 Volume 42(Issue 11) pp:3804-3810
Publication Date(Web):March 26, 2009
DOI:10.1021/ma900182s
Narrowly distributed polyethylene-b-poly(ethylene oxide) diblock copolymers (PE-b-PEO) with a linear PE block were successfully synthesized by combination of click coupling reaction of azido-terminated polyethylene (PE−N3) and alkynyl-terminated poly(ethylene oxide) (PEO−CONHCH2C≡CH). PE−N3 derived from tosylation and subsequent substitution by sodium azide of hydroxyl-terminated PE (PE−OH) which was prepared by means of chain shuttling ethylene polymerization with 2,6-bis[1-(2,6- dimethylphenyl)imino ethyl] pyridine iron (II) dichloride (complex 1)/methylaluminoxane (MAO)/diethyl zinc (ZnEt2) and subsequent in situ oxidation with oxygen. PEO−CONHCH2C≡CH was synthesized through esterification the hydroxyl end-group on hydroxyl-terminated PEO (PEO−OH) with phosgene and subsequent amidation by propargyl amine. The self-assembly of three double-crystalline PE-b-PEO samples with different block length in water were investigated by laser light scattering (LLS) and transmission electron microscopy (TEM). It was found that, in water, a solvent selectively good for the PEO block, PE-b-PEO chains with proper PE block length could form spherical multicores micelles with the insoluble and crystallized PE blocks as the multicores and the soluble and swollen PEO blocks as the shell. These multicores in one micelle could reaggregate to a single-core as temperature increased. Differential scanning calorimetry (DSC) experiments showed that the crystallization of both PE and PEO blocks was intensely confined by the previously self-assembled structure of PE-b-PEO in aqueous solution.
Co-reporter:Yuan-Yuan Wang;Shang-An Lin;Fang-Ming Zhu;Hai-Yang Gao ;Qing Wu
Journal of Applied Polymer Science 2008 Volume 110( Issue 6) pp:3590-3595
Publication Date(Web):
DOI:10.1002/app.28759
Abstract
The polymerization of norbornene (NBE) was investigated in the presence of two novel pyrazolylimine nickel complexes [2-(C3HN2Me2-3,5){C(Ph)[4-R2C6H2(R1)2-2,6]}NiBr2 (complex 1, R1 = iPr and R2 = H; complex 2, R1 = H and R2 = NO2)] activated by methylaluminoxane. The two catalytic systems showed high activity [up to 1.27 × 106 g of polynorbornene (PNBE)/(mol of Ni h)] for NBE polymerization and provided PNBEs with high molecular weights (weight-average molecular weight ≤ 17.46 × 105 g/mol) and narrow molecular weight distributions (ca. 2). The electron withdrawing of the nitro group in complex 2 could not enhance the catalytic activity for NBE polymerization; however, the molecular weights of the polymers were increased. The catalytic activity, molecular weight, and molecular weight distribution were influenced by the polymerization conditions, such as the polymerization temperature and Al/Ni molar ratios. The obtained PNBEs were characterized by means of 1H-NMR and Fourier transform infrared spectroscopy techniques. The analysis results for PNBEs indicated that the NBE polymerization was a vinyl-type polymerization rather than a ring-opening metathesis polymerization. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Ting Li;Chuan Hui Zhang;Fang Ming Zhu;Qing Wu
Journal of Applied Polymer Science 2008 Volume 108( Issue 1) pp:206-210
Publication Date(Web):
DOI:10.1002/app.27499
Abstract
Unsymmetrical α-diimine ligand 1 was successfully synthesized via condensation of trimethylaluminum (TMA) metalated 2-methyl-6-isopropyl-aniline with rigid bicyclic aliphatic diketone camphorquinone. Syn- and anti-stereoisomers were detected by 13C NMR in the condensation product. The corresponding α-diimine nickel (II) complex 1 was prepared from the exchange reaction of (DME)NiBr2 with the ligand 1, and displayed high activity for ethylene polymerization in the presence of diethylaluminum chloride (AlEt2Cl). The resultant polymers were confirmed by gel permeation chromatography and 13C NMR characterization to be broad molecular weight distribution polyethylene with various branches, and high degree of branching, even at low polymerization temperature −10°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Yunbo Li, Xudong Chen, Mingqiu Zhang, Weiang Luo, Jin Yang and Fangming Zhu
Macromolecules 2008 Volume 41(Issue 13) pp:4873-4880
Publication Date(Web):2017-2-22
DOI:10.1021/ma702800p
On the basis of the relationship between macromolecular aggregate and resonance Rayleigh scattering (RRS) intensity, RRS spectra were utilized to monitor macromolecular aggregating process in poly(acrylic acid) (PAA). No probe and labeling were incorporated; RRS can reveal the macromolecule extension or contraction under external stimuli such as the changes in pH and ionic strength, as well as the addition of surfactant. Results indicated that the addition of base, acid and NaCl altered macromolecular phase behavior of PAA in aqueous solution due to electrostatic effect. Besides, sodium dodecyl sulfate (SDS) or cetyltrimethylammonium bromide (CTAB) interacted with PAA in solution to form polymer-surfactants complexes, inducing macromolecular chain aggregate. On the basis of the analysis of the results, two models were proposed in this work to explain the observed phenomena. RRS is a sensitive method to characterize the macromolecular aggregate.
Co-reporter:WanJuan Wang, Ting Li, Ting Yu and FangMing Zhu
Macromolecules 2008 Volume 41(Issue 24) pp:9750-9754
Publication Date(Web):December 2, 2008
DOI:10.1021/ma802291w
Diends-azido-terminated and diends-alkynyl-terminated poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymers (N3-PEO-b-PPO-b-PEO-N3 and HC≡C-PEO-b-PPO-b-PEO-C≡CH) were respectively prepared and used together as the precursors for multiblock copolymer synthesis through coupling reaction by combination of self-assembly and click chemistry. The self-assembly of equimolar resultant triblock copolymers in water, a selective solvent for PEO, results in a core−shell structure with the insoluble and collapsed PPO blocks as the core and the soluble and swollen PEO blocks as the shell. The self-assembly concentrates and exposes the azido and alkynyl end groups on the periphery. The multiple click coupling reactions between the self-assembled diends-functionalized triblock copolymers were performed, leading to the highly efficient formation of −(−PEO-b-PPO-b-PEO−)n− multiblock copolymer chains. In comparison, the click coupling reaction was also presented in N,N-dimethylformamide (DMF) solution without self-assembly. It was found that the efficiency of the coupling reaction was very low, and no long multiblock copolymer chains were produced.
Co-reporter:Dan Liu;Shangan Lin;Haiyang Gao;Qing Wu
Polymer Bulletin 2008 Volume 61( Issue 1) pp:71-80
Publication Date(Web):2008 July
DOI:10.1007/s00289-008-0934-6
The novel half-titanocene catalyst bearing reactive functional amino group, η5-pentamethylcyclopentadienyltri(p-amino-phenoxyl) titanium [Cp∗Ti(p-OC6H4NH2)3],
was easily synthesized by the reaction of η5-pentamethylcyclopentadienyltrichloride
titanium (Cp∗TiCl3) with p-amino
phenol in the presence of triethyl amine (NEt3). Cp∗Ti(p-OC6H4NH2)3
covalently anchored on MgCl2/AlEtn(OEt)3-n
support obtained from the reaction of triethylaluminium (AlEt3) with the adduct
of magnesium chloride (MgCl2) and ethanol (EtOH), has been investigated and used
to catalyze syndiospecific polymerization of styrene. Influences of the support structure, cocatalyst,
and the molar ratio of Al in methylaluminoxane (MAO) and Ti (AlMAO/Ti) on catalytic
activity, syndiotacticity and molecular weight of the resultant polystyrene were investigated. Compared
with the corresponding Cp∗Ti(p-OC6H4NH2)3
homogeneous catalyst, a considerable increase in activity and molecular weight of syndiotactic polystyrene
(sPS) was observed for the Cp∗Ti(p-OC6H4NH2)3-MgCl2/AlEtn(OEt)3-n
supported catalyst even at a relatively low AlMAO/Ti ratio of 50, and the kinetics
of polymerization was stable during the reaction process.
Co-reporter:Hao Zou;Qing Wu
Journal of Polymer Science Part A: Polymer Chemistry 2008 Volume 46( Issue 6) pp:2186-2192
Publication Date(Web):
DOI:10.1002/pola.22553
Abstract
The copolymerization of ethylene with cyclopentene catalyzed by three α-diimine nickel(II) complexes in the presence of methylaluminoxane (MAO) was investigated. High-molecular-weight branched ethylene/cyclopentene copolymers with only cis-1,3-enchained cyclopentene units, which has not been reported previously, were obtained. The catalytic activity, cyclopentene incorporation, copolymer molecular weight, and molecular-weight distribution could be controlled over a wide range through the variation of the catalyst structure and polymerization conditions, including cyclopentene concentration in the feed and polymerization temperature. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2186–2192, 2008
Co-reporter:Hao Zou, Sheng Hu, Huahua Huang, Fangming Zhu, Qing Wu
European Polymer Journal 2007 Volume 43(Issue 9) pp:3882-3891
Publication Date(Web):September 2007
DOI:10.1016/j.eurpolymj.2007.06.028
A series of unsymmetrical complexes of 2,3-bis(2-phenylphenyl)-butanediimine nickel(II) dibromide (complex 1), 1,4-bis(2-isopropyl-6-methylphenyl)-acenaphthenediimine nickel(II) dibromide (complex 2) and meso- and rac-1,4-bis (2,4-di-tert-butyl-6-methylphenyl)-acenaphthenediimine nickel(II) dibromide (meso-3 and rac-3) were synthesized and activated by methylaluminoxane (MAO) for ethylene polymerization. By 13C NMR characterization, meso- and rac-stereo-isomers were detected in the condensation products resulting from the reaction of unsym-substituted anilines with diketones. It was notable that meso- and rac-isomers in ligand 1 or ligand 2 could not be separated owing to their interconversion, however, meso- and rac-isomers in ligand 3 could be isolated and identified by X-ray diffraction and NMR analysis. At low polymerization temperatures, complex 1/MAO afforded polyethylene with bimodal molecular weight distribution, while complex 2/MAO prepared polyethylene with single-modal distribution. Moreover, by raising polymerization temperature or extending time of catalyst aging, bimodal molecular weight distribution polyethylene was also produced by complex 2/MAO. The hypothesis of bimodal molecular weight distribution polyethylene synthesized by unsymmetrical α-diimine nickel(II) complexes was supported that the molecular weight of polyethylene produced by rac-3/MAO was significantly higher than that produced by meso-3/MAO under identical polymerization conditions. A unique methodology to prepare polyethylene with bimodal molecular weight distribution was demonstrated.
Co-reporter:Yugang Huang, Yonghong Zeng, Jianwen Yang, Zhaohua Zeng, Fangming Zhu and Xudong Chen
Chemical Communications 2011 - vol. 47(Issue 26) pp:NaN7511-7511
Publication Date(Web):2011/05/31
DOI:10.1039/C1CC12177D
Rapid and highly efficient side-chain functionalization of polypeptides was achieved via combination of ring-opening polymerization of a new clickable monomer of γ-propargyl-L-glutamateN-carboxyanhydride (PLG-NCA) and thiol-yne photochemistry, which provides a convenient and universal route to prepare diverse polypeptide-based biomimetic hybrid materials.
Co-reporter:Shuo Feng, Yuenan Chen, Biyun Mai, Wanchu Wei, Caixia Zheng, Qing Wu, GuoDong Liang, HaiYang Gao and FangMing Zhu
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 30) pp:NaN15947-15947
Publication Date(Web):2014/06/18
DOI:10.1039/C4CP01849D
Surfactant-free nanospheres and latex nanospheres of poly(methyl methacrylate) (PMMA) with diameter ranging from 20 to 220 nm are prepared by atom transfer radical polymerization (ATRP) in microemulsions and subsequent dialysis against deionized water. The glass transitions of these PMMA nanospheres are characterized using nano differential scanning calorimetry (nano-DSC) in aqueous dispersions. The glass transition temperature (Tg) of the surfactant-free PMMA nanospheres and nonionic PMMA latex nanospheres with diameters below 150 nm is less than that of the PMMA bulk, and Tg decreases with the decrease of the diameter. In contrast, Tg of the anionic PMMA latex nanospheres is size-independent and is near to that of the PMMA bulk. The influence of the environment surrounding the PMMA nanospheres on glass transitions as well as comparisons to our prior studies with polystyrene (PS) nanospheres in aqueous dispersions are discussed.
