Lianxun Gao

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Name: 高连勋; LianXun Gao

Organization: Chinese Academy of Science and Graduate School of Chinese Academy of Sciences , China

Department: Changchun Institute of Applied Chemistry

Title: Professor(PhD)

TOPICS

Polymer

Phosphorus Flame Retardant

Organic Chemistry

Phosphorus Flame Retardant

Chemicals
References

Effect of multiple H-bonding on the properties of polyimides containing the rigid rod groups

Co-reporter:Xiaoye Ma;Chuanqing Kang;Wenhui Chen;Rizhe Jin;Haiquan Guo;Xuepeng Qiu

Journal of Polymer Science Part A: Polymer Chemistry 2016 Volume 54( Issue 4) pp:570-581

Publication Date(Web):

DOI:10.1002/pola.27808

ABSTRACT

To investigate the influence of hydrogen bonding on the properties of polyimides (PIs) containing rigid rod-like groups, five symmetrical diamines containing benzimidazole, benzoxazole, and hydroxy group were synthesized, and then a series of PIs were prepared. Results showed that hydroxyl-containing poly(benzoxazole imide)s possess higher glass transition temperature (T_g) and dimensional stabilities than their corresponding poly(benzoxazole imide)s. Moreover, the corresponding poly(benzimidazole imide)s presented the best performances, such as the highest T_g, the highest char yield and the highest dimensional stabilities. The influence of hydrogen bonding of benzimidazole on the properties of PIs was stronger than that of hydroxyl groups. Hydroxyl-containing poly(benzoxazole imide)s were formed in crosslinking structures after heat treatment at 400 °C. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 570–581

Sulfonated polyimides containing 1,2,4-triazole groups for proton exchange membranes

Co-reporter:Rui Lei;Lian-xun Gao 高连勋;Ri-zhe Jin;Xue-peng Qiu

Chinese Journal of Polymer Science 2014 Volume 32( Issue 7) pp:941-952

Publication Date(Web):2014 July

DOI:10.1007/s10118-014-1460-7

A series of sulfonated polyimide copolymers as novel proton exchange materials were synthesized by the polycondensation of 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTDA), sulfonated diamine based on pyridine group and diamine containing N-phenyl-1,2,4-triazole moiety. Flexible, transparent and tough membranes with high thermal stability and good mechanical properties were obtained. They exhibited good stability in boiling water and Fenton’s reagent at 80 °C. More interestingly, a nonlinear relationship between proton conductivities of the resulting membranes and the degree of sulfonation (DS) was observed. The membrane with 50% DS exhibited the maximum proton conductivity, which was due to the combinational contributions of sulfonic acid and N-pheny-1,2,4-triazole groups. Thus, the N-phenyl-1,2,4-triazole moiety in this study not only can depress water absorption but also increase proton conductivity, especially at low DS.

ZIF-8 crystal coatings on a polyimide substrate and their catalytic behaviours for the Knoevenagel reaction

Co-reporter:Rizhe Jin, Zheng Bian, Jizhen Li, Mengxian Ding and Lianxun Gao

Dalton Transactions 2013 vol. 42(Issue 11) pp:3936-3940

Publication Date(Web):11 Dec 2012

DOI:10.1039/C2DT32161K

ZIF-8 crystal coatings were prepared by direct growth on different flexible polyimide substrates including a thin membrane and electrospun nanofiber mat. In SEM pictures, the ZIF-8 crystals exhibit a rhombic dodecahedron morphology. Owing to the flexible polyimide substrate, the MOF–polymer film may be moderately bent or easily tailored when not destroyed. The ZIF-8 coatings can be activated at high temperature owing to the excellent thermal resistance and low coefficient of thermal expansion of the polyimide. Furthermore, this material may be used as an efficient heterogeneous catalyst for the Knoevenagel reaction and can be easily recovered. The ZIF-8 coatings and 2-methylimidazole show similar catalytic behaviour as a weak base.

Preparation and properties of ionic cross-linked sulfonated copolyimide membranes containing pyrimidine groups

Co-reporter:Rizhe Jin;Yuhan Li;Wei Xing;Xuepeng Qiu;Xiangling Ji

Polymers for Advanced Technologies 2012 Volume 23( Issue 1) pp:31-37

Publication Date(Web):

DOI:10.1002/pat.1835

Abstract

A series of sulfonated copolyimides containing pyrimidine groups (SPIs) were synthesized by random copolymerization of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 2-(4-aminophenyl)-5-aminopyrimidine (PAPRM), and 4,4′-diaminodiphenyl ether-2,2′-disulfonic acid (ODADS). Proton exchange treatment in 1.0 M sulfuric acid solution resulted in ionic cross-linking of the sulfonated copolymers due to the acid (sulfonic acid)-base (pyrimidine group) interactions and the membrane with more basic PAPRM moiety could absorb sulfuric acid to favor the proton transfer. The effects of the structure of the diamines on the properties of SPI membranes were evaluated by studying the membrane parameters including water uptake, proton conductivity, water stability, and methanol permeability. The basic pyrimidine groups introduced in the main chains could effectively resist membrane swelling due to the strong interchain interactions through basic pyrimidine groups and sulfonic acid groups. Compared with the corresponding uncross-linked copolyimides (NTDA/ODADS/ODA), the acid–base copolyimides displayed excellent water stability. The SPI membranes also exhibited improved mechanical properties and decreased methanol permeability. However, the cross-linked membranes showed lowered proton conductivities than the uncross-linked ones because a small part of the sulfonic acid groups had been consumed during the cross-linking process. Copyright © 2010 John Wiley & Sons, Ltd.

Donor-Induced Helical Inversion of 1,1-Binaphthyl Connecting with Two Molybdenum Complexes

Co-reporter:Dr. Li Ma;Dr. Rizhe Jin;Dr. Zheng Bian;Dr. Chuanqing Kang;Yu Chen; Jingwei Xu; Lianxun Gao

Chemistry - A European Journal 2012 Volume 18( Issue 41) pp:13168-13172

Publication Date(Web):

DOI:10.1002/chem.201201671

Abstract

An atropisomeric biaryl molecule with a given absolute configuration could present two opposite helical conformations through the rotation around CC single bond. To the best of our knowledge, the biaryl system is the simplest helical inversion model apart from stereomutation between two enantiomers. Herein, we first report such true helical inversion phenomena of biaryl compounds. Two [Mo^VIO₂(L)]-type complexes, in which L is a tridentate dioxoanionic pyridine O,N,O-ligand, are coalesced on the 2,2′,3,3′-positions of an (R)-1,1′-binaphthyl unit and an intramolecular dioxo bridge is formed by two MoO⋅⋅⋅Mo interactions. Exterior strong donors can coordinate to molybdenum to interrupt this dioxo bridge and inversions from negative to positive chirality are explicitly observed by circular dichroism spectroscopy, consistent with single-crystal X-ray diffraction analyses.

In Situ Gel-to-Crystal Transition and Synthesis of Metal Nanoparticles Obtained by Fluorination of a Cyclic -Aminoalcohol Gelator

Co-reporter:Yang Xu;Dr. Chuanqing Kang;Yu Chen;Dr. Zheng Bian;Dr. Xuepeng Qiu;Dr. Lianxun Gao;Dr. Qingxin Meng

Chemistry - A European Journal 2012 Volume 18( Issue 52) pp:16955-16961

Publication Date(Web):

DOI:10.1002/chem.201202615

Abstract

A new fluorinated version of a cyclic β-aminoalcohol gelator derived from 1,2,3,4-tetrahydroisoquinoline is presented. The gelator is able to gel various nonprotic solvents through OH⋅⋅⋅N hydrogen bonds and additional CH⋅⋅⋅F interactions due to the introduction of fluorine. A bimolecular lamellar structure is formed in the gel phase, which partly preserves the pattern of molecular organization in the single crystal. The racemate of the chiral gelator shows lower gelation ability than its enantiomer because of a higher tendency to form microcrystals, as shown by X-ray diffraction analysis. The influence of fluorination on the self-assembly of the gelator and the properties of the gel was investigated in comparison to the original fluorine-free gel system. The introduction of fluorine brings two new features. The first is good recognition of o-xylene by the gelator, which induces an in situ transition from gels of o-xylene and of an o-xylene/toluene mixture to identical single crystals with unique tubular architecture. The second is the enhanced stability of the toluene gel towards ions, including quaternary ammonium salts, which enables the preparation of a stable toluene gel in the presence of chloroaurate or chloroplatinate. The gel system can be used as a template for the synthesis of spherical gold nanoparticles with a diameter of 5 to 9 nm and wormlike platinum nanostructures with a diameter of 2 to 3 nm and a length of 5 to 12 nm. This is the first example of a synthesis of platinum nanoparticles in an organogel medium. Therefore, the appropriate introduction of a fluorine atom and corresponding nonbonding interactions into a known gelator to tune the properties and functions of a gel is a simple and effective tactic for design of a gel system with specific targets.

An organogel formed from a cyclic β-aminoalcohol

Co-reporter:Chuanqing Kang, Zheng Bian, Yabing He, Fushe Han, Xuepeng Qiu and Lianxun Gao

Chemical Communications 2011 vol. 47(Issue 38) pp:10746-10748

Publication Date(Web):24 Aug 2011

DOI:10.1039/C1CC13179F

A new organogelator with unique structural feature of a cyclic β-aminoalcohol is presented as the first example of gelation by aminoalcohol through hydrogen-bonding between hydroxy and amine.

Self-discriminating and hierarchical assembly of racemic binaphthyl-bisbipyridines and silver ions: from metallocycles to gel nanofibers

Co-reporter:Yabing He, Zheng Bian, Chuanqing Kang and Lianxun Gao

Chemical Communications 2011 vol. 47(Issue 5) pp:1589-1591

Publication Date(Web):29 Nov 2010

DOI:10.1039/C0CC03192E

A heterochiral metallocycle was formed by self-discriminating assembly of racemic bisbipyridines and silver ions, and further self-organized into nanofibers immobilizing organic solvents in a distinct pattern from the enantiopure version reported by us previously.

Sulfonated polyimides containing pyridine groups as proton exchange membrane materials

Co-reporter:Rui Lei;Chuan-qing Kang;Yun-jie Huang;Xue-peng Qiu

Chinese Journal of Polymer Science 2011 Volume 29( Issue 5) pp:532-539

Publication Date(Web):2011 September

DOI:10.1007/s10118-011-1063-5

A series of sulfonated polyimides (SPIs) containing pyridine groups were prepared by direct polycondensation from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 4,4′-diaminodiphenyl ether-2,2′-disulfonic acid (ODADS) and 4-(4-methoxy)phenyl-2,6-bis(4-aminophenyl)pyridine (DAM). The resulting copolymers displayed good solubility in common organic solvents. Flexible, transparent, tough membranes were obtained via solution casting. All the films showed high thermal stability with desulfonation temperature over 300°C. They exhibited prominent mechanical properties with Young’s modulus around 2.0 GPa. High proton conductivity (0.23 S/cm at 100% RH) was also observed. More importantly, the new materials exhibited low water uptake (30 wt%–75 wt% at 80°C) and improved water stability, which were attributed to the acid-base interaction between sulfonic acid and pyridine functional groups.

Stereoselective and hierarchical self-assembly from nanotubular homochiral helical coordination polymers to supramolecular gels

Co-reporter:Yabing He, Zheng Bian, Chuanqing Kang and Lianxun Gao

Chemical Communications 2010 vol. 46(Issue 31) pp:5695-5697

Publication Date(Web):01 Jul 2010

DOI:10.1039/C0CC01433H

A new binaphthylbisbipyridine-based ligand underwent diastereoselective self-assembly with silver(I) ions to form nanotubular homochiral helical coordination polymers, which further hierarchically self-assemble into nanofibers, capable of immobilizing organic solvents.

Chiral binaphthylbisbipyridine-based copper(I) coordination polymer gels as supramolecular catalysts

Co-reporter:Yabing He, Zheng Bian, Chuanqing Kang, Yanqin Cheng and Lianxun Gao

Chemical Communications 2010 vol. 46(Issue 20) pp:3532-3534

Publication Date(Web):29 Mar 2010

DOI:10.1039/B926936C

A novel class of chiral coordination polymer organogels, with multi–stimuli responsive properties and suitable for use as catalysts in 1,3-dipolar Huisgen cycloaddition reaction, are reported.

Novel C3-symmetrical triphenylbenzene-based organogelators with different linkers between phenyl ring and alkyl chain

Co-reporter:Yabing He, Zheng Bian, Chuanqing Kang, Yanqin Cheng, Lianxun Gao

Tetrahedron 2010 66(19) pp: 3553-3563

Publication Date(Web):

DOI:10.1016/j.tet.2010.02.094

Ultrasound-promoted chiral fluorescent organogel

Co-reporter:Yabing He, Zheng Bian, Chuanqing Kang, Rizhe Jin and Lianxun Gao

New Journal of Chemistry 2009 vol. 33(Issue 10) pp:2073-2080

Publication Date(Web):30 Jul 2009

DOI:10.1039/B909127K

In this paper, we have described a chiral binaphthyl-based fluorescent organogel. Very interestingly, similar to sonocrystallisation of organics, ultrasound can promote the gelation while it cannot occur spontaneously at relatively high temperature or low concentration. The fluorescence enhancement of the gel obtained via ultrasound irradiation is observed. In solution there exist rapid dynamic equilibria between (S)-1 oligomers. The association interactions both between gelator molecules and between solvent and gelator molecules could together effect the helical growth of distorted (S)-1nanocrystals. The dihedral angle between the two naphthyl rings of the 1,1′-binaphthyl unit in (S)-1 will increase upon gelation. It has been assumed that ultrasound can play an important role in gelation with a high energy barrier. Sonication-induced gelation is a rapid crystallisation behavior yielding fiber-like aggregates in a metastable system.

Novel sulfonated polyimide ionomers by incorporating pyridine functional group in the polymer backbone

Co-reporter:Rui Lei;Chuanqing Kang;Yunjie Huang;Yuhan Li;Xi Wang;Rizhe Jin;Xuepeng Qiu;Xiangling Ji;Wei Xing

Journal of Applied Polymer Science 2009 Volume 114( Issue 5) pp:3190-3197

Publication Date(Web):

DOI:10.1002/app.30929

Abstract

A series of sulfonated polyimides (SPIs) containing pyridine ring in the polymer backbone were synthesized by the polycondensation of 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTDA), 5-(2,6-bis(4-aminophenyl)pyridin-4-yl)-2-methoxy benzene sulfonic acid (SDAM), and 4,4′-diaminodiphenyl ether (ODA). Flexible, transparent, and tough membranes were obtained. Property study revealed that all the membranes displayed high thermal stability with the desulfonation and decomposition temperature higher than 290 and 540°C, respectively, as well as good mechanical property with Young's modulus larger than 1.0 GPa, maximum strength (MS) on a scale of 60–80 MPa, and elongation at break (EB) ranged from 41.79 to 75.17%. More importantly, the new materials exhibited small water uptake and excellent dimensional stability with the highest sulfonated SPI-80 showing the maximum water uptake of 36.1%, and maximum swollen ratio of Δt = 0.038 and Δl = 0.026, respectively (Δt and Δl stands for the thickness and diameter change of the film, respectively). The high water stability exhibited by the SPI films is attributed to the formation of inner salts and/or ionic crosslinking between the sulfonic acid and pyridine functional groups, which suppresses the water uptake ability of sulfonic acid and strengthened the interpolymer chain interactions. Thus, the excellent water stability, good thermal and mechanical properties, and the technologically applicable conductivity of SPI-80 render this material attractive for proton exchange membrane (PEM) application. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Asymmetric Michael addition of aldehydes to nitroolefins catalyzed by l-prolinamide derivatives using phenols as co-catalysts

Co-reporter:Yan-Qin Cheng, Zheng Bian, Ya-Bing He, Fu-She Han, Chuan-Qing Kang, Zhao-Lun Ning, Lian-Xun Gao

Tetrahedron: Asymmetry 2009 Volume 20(Issue 15) pp:1753-1758

Publication Date(Web):12 August 2009

DOI:10.1016/j.tetasy.2009.07.022

The asymmetric Michael addition of aldehydes to nitroolefins was investigated using l-prolinamide derivatives of 2-(2′-piperidinyl)pyridine as catalyst and a variety of phenols as co-catalyst. Extensive screening toward the effect of prolinamides, phenols, and solvents on this transformation revealed that a combination of (S)-2-(2′-piperidinyl)pyridine-derived trans-4-hydroxy-l-prolinamide 2c, (S)-1,1′-bi-2-naphthol, and dichloromethane was a promising system. This system was shown to be amenable to a rich variety of aldehydes and nitroolefins and afforded the nitroaldehyde products with excellent yield, enantiomeric excess (up to 99%) and diastereoselectivity ratio (up to 99/1), even in the case of 1 mol % catalyst loading and 1.5 equiv of aldehydes.(S)-2-(2′-Piperidinyl)pyridine derived l-prolinamideC15H21N3O[α]D20=-198.4 (c 0.64, CH2Cl2)Source of chirality: l-proline and (S)-2-(2′ piperidinyl) pyridineAbsolute configuration: (S, 2S)(R)-2-(2′-Piperidinyl)pyridine derived l-prolinamideC15H21N3O[α]D20=+70.0 (c 1, CH2Cl2)Source of chirality: l-proline and (R)-2-(2′-piperidinyl) pyridineAbsolute configuration: (R, 2S)(S)-2-(2′-Piperidinyl)pyridine derived trans-4-hydroxy-l-prolinamideC15H21N3O2[α]D20=-100.0 (c 0.1, CH2Cl2)Source of chirality: trans-4-hydroxy-l-proline and (S)-2-(2′-piperidinyl) pyridineAbsolute configuration: (S, 2S, 4R)(R)-2-(2′-Piperidinyl)pyridine derived trans-4-hydroxy-l-prolinamideC15H21N3O2[α]D20=+61.7 (c 0.47, CH2Cl2)Source of chirality: trans-4-hydroxy-l-proline and (R)-2-(2′-piperidinyl) pyridineAbsolute configuration: (R, 2S, 4R)

Synthesis and properties of silicapolyimide hybrid films derived from colloidal silica particles and polyamic acid

Co-reporter:Zhenping Shang;Changli Lü;Xiaodan Lü

Journal of Applied Polymer Science 2008 Volume 109( Issue 6) pp:3477-3483

Publication Date(Web):

DOI:10.1002/app.27657

Abstract

A series of SiO₂/polyimide hybrid films with different contents and sizes of SiO₂ particles were prepared by blending polyamic acid (PAA) and SiO₂ nanoparticles obtained from Stöber method, followed by a step thermal imidization process. The size and content effect of SiO₂ particles on the mechanical and thermal properties was studied. It was found that as the silica particles were introduced into polyimide matrix, T_gs of hybrid films increased on the whole and there was a maximum value of T_g for the hybrid film with 10-nm SiO₂ particles. TGA indicated that the thermal stability for hybrid films decreased with the increasing content and size of SiO₂ particles. Dynamic mechanical thermal analysis (DMTA) indicated that the modulus of hybrid films increased, while the tensile strength and elongation at break decreased as the size of SiO₂ particles increases from 10 to 25 nm and to 65 nm. All polyimide hybrid films were amorphous according to X-ray determination. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Palladium within ionic liquid functionalized mesoporous silica SBA-15 and its catalytic application in room-temperature Suzuki coupling reaction

Co-reporter:Peng Han, Hongming Zhang, Xuepeng Qiu, Xiangling Ji, Lianxun Gao

Journal of Molecular Catalysis A: Chemical 2008 Volume 295(1–2) pp:57-67

Publication Date(Web):12 November 2008

DOI:10.1016/j.molcata.2008.08.016

Initially, pore walls of mesoporous silica SBA-15 with template were modified with chlorotrimethylsilane. Then imidazolium salts were similarly incorporated covalently in the inner pore walls of mesoporous silica SBA-15 albeit without the template. Finally, palladium salts were introduced into the pore channels of the previously processed mesoporous silica via electrostatic interaction. The resulting palladium catalysts demonstrated exceptional activity for the room-temperature Suzuki coupling reaction in aqueous-organic mixed solvents and good recycling ability for at least 4–6 times. The turnover frequency of resulting catalysts could reach up to 84,000 h−1 at 50 °C. The corresponding samples were analyzed with solid-state NMR, FT-IR, XRD, nitrogen adsorption–desorption isotherms, TEM and XPS techniques. In addition, agglomeration of palladium catalyst in the Suzuki coupling reaction can be effectively controlled due to the stabilizing effect of the imidazulium salt and confinement of mesoporous walls.Palladium salts were introduced into the pore channels of the imidazolium salts-functionalized mesoporous silica SBA-15 via electrostatic interaction. The resulting palladium catalysts demonstrated exceptional activity for the room-temperature Suzuki coupling reaction in aqueous-organic mixed solvents and good recycling ability. In addition, agglomeration of palladium catalyst in the Suzuki coupling reaction can be effectively controlled due to the stabilizing effect of the imidazulium salt and confinement of mesoporous walls.

Chiral ligand 2-(2′-piperidinyl)pyridine: synthesis, resolution and application in asymmetric diethylzinc addition to aldehydes

Co-reporter:Yan-Qin Cheng, Zheng Bian, Chuan-Qing Kang, Hai-Quan Guo, Lian-Xun Gao

Tetrahedron: Asymmetry 2008 Volume 19(Issue 13) pp:1572-1575

Publication Date(Web):11 July 2008

DOI:10.1016/j.tetasy.2008.06.005

Chiral ligand 2-(2′-piperidinyl)pyridine 1 has been synthesized in good overall yield by sequential benzylation, hydrogenation and debenzylation of 2,2′-bipyridine. Its enantiomerically pure enantiomers have been obtained by resolution of 2-(1-benzyl-2-piperidinyl)pyridine 2 with d-tartaric acid (or l-tartaric acid) followed by debenzylation. The absolute configuration was determined by X-ray analysis of the (S)-2d-tartrate. It was demonstrated that 1 can be used as an effective enantioselective catalyst in the addition of diethylzinc to aldehydes. Optically active secondary alcohols with up to 100% enantiomeric excess were obtained in high yields..(S)-2-(1-Benzyl-2-piperidinyl)pyridineC17H20N2[α]D20=-60.5 (c 0.55, ethanol)Absolute configuration: (S)(S)-2-(2′-Piperidinyl)pyridineC10H14N2[α]D20=-47.0 (c 0.62, ethanol)Absolute configuration: (S)

Highly efficient and recoverable dendritic organocatalyst from click chemistry for the asymmetric michael addition of ketones to nitroolefins without the use of organic solvent

Co-reporter:Guanghua Lv, Rizhe Jin, Wenpeng Mai, Lianxun Gao

Tetrahedron: Asymmetry 2008 Volume 19(Issue 22) pp:2568-2572

Publication Date(Web):17 November 2008

DOI:10.1016/j.tetasy.2008.10.016

A series of pyrrolidine-triazole based dendritic catalysts have been synthesized and applied directly in the asymmetric Michael addition of ketones to nitroolefins without the use of an organic solvent. Good yields (up to 99%), and high diastereoselectivities (up to syn/anti = 45:1) and enantioselectivities (up to 95% ee) have been obtained. Furthermore, the third generation catalyst can be reused at least five times without significant loss of catalytic activity.(S)-4-(4-((3,5-Bis(benzyloxy)benzyloxy)methyl)phenyl)-1-(pyrrolidin-2-ylmethyl)-1H-1,2,3-triazoleC35H36N4O3[α]D20=+9.1 (c 1.0, CH2Cl2)Absolute configuration: (S)Source of chirality: l-proline(S)-4-(4-((3,5-Bis(3,5-bis(benzyloxy)benzyloxy)benzyloxy)methyl)phenyl)-1-(pyrrolidin-2-ylmethyl)-1H-1,2,3-triazoleC63H60N4O7[α]D20=+4.5 (c 1.0, CH2Cl2)Absolute configuration: (S)Source of chirality: l-proline(S)-4-(4-((3-(3,5-Bis(3,5-bis(benzyloxy)benzyloxy)benzyloxy)-5-(3-(2,4-bis(benzyloxy)benzyloxy)-5-(3,5-bis(benzyloxy)benzyloxy)benzyloxy)benzyloxy)methyl)phenyl)-1-(pyrrolidin-2-ylmethyl)-1H-1,2,3-triazoleC119H108N4O15[α]D20=+2.8 (c 1.0, CH2Cl2)Absolute configuration: (S)Source of chirality: l-proline

Glass wafers bonding via Diels–Alder reaction at mild temperature

Co-reporter:Minjie Zhang, Jianying Zhao, Lianxun Gao

Sensors and Actuators A: Physical 2008 Volume 141(Issue 1) pp:213-216

Publication Date(Web):15 January 2008

DOI:10.1016/j.sna.2007.08.001

In this paper, we introduced a novel bonding method of glass wafers by Diels–Alder reaction at mild temperature. After standard hydroxylization and aminosilylation, two wafers were modified by 2-furaldehyde and maleic anhydride, respectively. Then they were brought into close contact and tightly held with a clamping fixture. A strong bonding could be achieved by annealing for 5 h at 200 °C. Bonding strength is as high as 1.78 MPa and sufficient for most application of microfluidic chips. This bonding process has the advantages of simple operation and good smoothness of the wafer surface. Mild temperature can prevent the channel of microfluidic chip distorted or collapse and shorten the cooling time.

Bonding quartz wafers by the atom transfer radical polymerization of the glycidyl methacrylate at mild temperature

Co-reporter:Jianying Zhao, Zhenping Shang, Lianxun Gao

Sensors and Actuators A: Physical 2007 Volume 135(Issue 1) pp:257-261

Publication Date(Web):30 March 2007

DOI:10.1016/j.sna.2006.06.070

In this paper, we presented a novel covalent bonding process between two quartz wafers at 300 °C. High-quality wafer bonding was formed by the hydroxylization, aminosilylation and atom transfer radical polymerization (ATRP) of glycidyl methacrylate (GMA), respectively, on quartz wafer surfaces, followed by close contact of the GMA functional wafer and the aminosilylation wafer, the epoxy group opening ring reaction was catalyzed by the amino and solidified to form the covalent bonding of the quartz wafers. The shear force between two wafers in all bonding samples was higher than 1.5 MPa. Microfluidic chips bonded by the above procedures had high transparency and the present procedure avoided the adhesive to block or flow into the channel.

Synthesis and properties of novel sulfonated polyimides containing binaphthyl groups as proton-exchange membranes for fuel cells

Co-reporter:Rizhe Jin;Yuhan Li;Zhen Wang;Zhiming Cui;Wei Xing

Journal of Polymer Science Part A: Polymer Chemistry 2007 Volume 45(Issue 2) pp:222-231

Publication Date(Web):5 DEC 2006

DOI:10.1002/pola.21778

A novel sulfonated diamine monomer, 2,2′-bis(p-aminophenoxy)-1,1′-binaphthyl-6,6′-disulfonic acid (BNDADS), was synthesized. A series of sulfonated polyimide copolymers containing 30–80 mol % BNDADS as a hydrophilic component were prepared. The copolymers showed excellent solubility and good film-forming capability. Atomic force microscopy phase images clearly showed hydrophilic/hydrophobic microphase separation. The relationship between the proton conductivity and degree of sulfonation was examined. The sulfonated polyimide copolymer with 60 mol % BNDADS showed higher proton conductivity (0.0945–0.161 S/cm) at 20–80 °C in liquid water. The membranes exhibited methanol permeability from 9 × 10⁻⁸ to 5 × 10⁻⁷ cm²/s at 20 °C, which was much lower than that of Nafion (2 × 10⁻⁶cm²/s). The copolymers were thermally stable up to 300 °C. The sulfonated polyimide copolymers with 30–60 mol % BNDADS showed reasonable mechanical strength; for example, the maximum tensile strength at break of the sulfonated polyimide copolymer with 40 mol % BNDADS was 80.6 MPa under high moisture conditions. The optimum concentration of BNDADS was found to be 60 mol % from the viewpoint of proton conductivity, methanol permeability, and membrane stability. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 222–231, 2007

Microstructure and properties of new polyimide/polysiloxane composite films

Co-reporter:Changli Lü;Zhen Wang;Jingling Yan;Feng Liu

Journal of Applied Polymer Science 2006 Volume 100(Issue 1) pp:124-132

Publication Date(Web):26 JAN 2006

DOI:10.1002/app.22532

A series of novel polyimide/polydiphenylsiloxane) (PI/PDDS) composite films with different contents of DDS were prepared using sol–gel method. The noncrosslinked PI–DDS and crosslinked PIS–DDS were synthesized through cohydrolysis and condensation between DDS and polyamic acid (PAA) or aminopropyltriethoxysilane(APTES)-terminated polyamic acid (PAAS). All the composite films have high thermal stability near pure PI. Field emission scanning electron microscopy (FE-SEM) study shows that the polysiloxane from hydrolyzed DDS well dispersed in polyimide matrix, without macroscopic separation for the composite films with low content of DDS, while large domain of polysiloxane was formed in films with high DDS content. The microstructure of composite films is in accordance with the transparency of corresponding films. X-ray study shows the PDDS is amorphous in PI matrix. The introduction of DDS into PI can improve the elongation at break and at the same time, the composite films still remained with higher modulus and tensile strength. The density and water absorption of the composite films decreased with the increasing DDS content. The composite films with DDS content below 10 wt % exhibit good solvent resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 124–132, 2006

Syntheses and properties of polyimides derived from diamines containing 2,5-disubstituted pyridine group

Co-reporter:Aixiang Xia;Haiquan Guo;Xuepeng Qiu;Mengxian Ding

Journal of Applied Polymer Science 2006 Volume 102(Issue 2) pp:1844-1851

Publication Date(Web):28 JUL 2006

DOI:10.1002/app.24083

A series of novel homo- and copolyimides containing pyridine units were prepared from the heteroaromatic diamines, 2,5-bis (4-aminophenyl) pyridine and 2-(4-aminophenyl)-5-aminopyridine, with pyromelltic dianhydride (PMDA), and 3,3′, 4,4′-biphenyl tertracarboxylic dianhydride (BPDA) via a conventional two-step thermal imidizaton method. The poly(amic acid) precursors have inherent viscosities of 1.60–9.64 dL/g (c = 0.5 g/dL in DMAC, 30°C) and all of them can be cast and thermally converted into flexible and tough polyimide films. All of the polyimides show excellent thermal stability and mechanical properties. The polyimides have 10% weight loss temperature in the range of 548–598°C in air. The glass transition temperatures of the PMDA-based samples are in the range of 395–438°C, while the BPDA-based polyimides show two glass transition temperatures (T_g1 and T_g2), ranging from 268 to 353°C and from 395 to 418°C, respectively. The flexible films possess tensile modulus in the range of 3.42–6.39 GPa, strength in the range of 112–363 MPa and an elongation at break in the range of 1.2–69%. The strong reflection peaks in the wide-angle X-ray diffraction patterns indicate that the polyimides have a high packing density and crystallinity. The polymer films are insoluble in common organic solvents exhibiting high chemical resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1844–1851, 2006

One-pot synthesis of polyetherimides from bis(chlorophthalimide) and dichlorodiphenylsulfone in diphenylsulfone

Co-reporter:Changli Lü;Jianying Zhao;Mengxian Ding;Jingling Yan;Zhenping Shang

Journal of Applied Polymer Science 2006 Volume 102(Issue 5) pp:4584-4588

Publication Date(Web):28 SEP 2006

DOI:10.1002/app.25051

Polyetherimides and copolymers have been synthesized in one pot from bis(chlorophthalimide), dichlorodiphenylsulfone, and bisphenolate using diphenylsulfone as the solvent. The inherent viscosities of the obtained polyimides are in the range of 0.32–0.72 dL/g, and the structures of polyimides were confirmed by IR and elemental analyses. All of the polyimides have good solubility in common organic solvents. The 5% weight-loss temperatures of the polyimides were 429–507°C in air. The glass transition temperatures (T_g) of 4,4′-(9-fluorenylidene) diphenol-based polyimides are in the range of 253–268°C. The T_g of bisphenol A-based polyimides is in the range of 198–204°C, while the T_g change inconspicuously when the ratios of diphenylsulfone increase. The wide-angle X-ray diffraction showed that all polyimides prepared are amorphous. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4584–4588, 2006

Syntheses and properties of novel polyimides derived from 2-(4-Aminophenyl)-5-aminopyrimidine

Co-reporter:Guanghua Lü;Aixiang Xia;Xuepeng Qiu;Haiquan Guo;Jianying Zhao;Mengxian Ding

Journal of Applied Polymer Science 2006 Volume 102(Issue 6) pp:5871-5876

Publication Date(Web):28 SEP 2006

DOI:10.1002/app.24988

2-(4-Aminophenyl)-5-aminopyrimidine (4) is synthesized via a condensation reaction of vinamidium salts and amidine chloride salts, followed by hydrazine palladium catalyzed reduction. A series of novel homo- and copolyimides containing pyrimidine unit are prepared from the diamine and 1,4-phenylenediamine (PDA) with pyromellitic dianhydride (PMDA) or 3,3′,4,4′-biphenyl tertracarboxylic dianhydride (BPDA) via a conventional two-step thermal imidization method. The poly(amic acid) precursors had inherent viscosities of 0.97–4.38 dL/g (c = 0.5 g/dL, in DMAc, 30°C) and all of them could be cast and thermally converted into flexible and tough polyimide films. All of the polyimides showed excellent thermal stability and mechanical properties. The glass transition temperatures of the resulting polyimides are in the range of 307–434°C and the 10% weight loss temperature is in the range of 556–609°C under air. The polyimide films possess strength at break in the range of 185–271 MPa, elongations at break in the range of 6.8–51%, and tensile modulus in the range of 3.5–6.46 GPa. The polymer films are insoluble in common organic solvents, exhibiting high chemical resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5871–5876, 2006

Preparation and properties of ternary polyimide/SiO2/polydiphenylsiloxane composite films

Co-reporter:Zhenping Shang;Changli Lü

Polymer International 2006 Volume 55(Issue 11) pp:

Publication Date(Web):23 JUN 2006

DOI:10.1002/pi.2078

A series of novel ternary polyimide/SiO₂/polydiphenylsiloxane (PI/SiO₂/PDPhS) composite films were prepared through co-hydrolysis and condensation between tetramethoxysilane, diphenyldimethoxysilane (DDS) and aminopropyltriethoxysilane-terminated polyamic acid, using an in situ sol–gel method. The composite films exhibited good optical transparency up to 30 wt% of total content of DDS and SiO₂. SEM analysis showed that the PDPhS and SiO₂ were well dispersed in the PI matrix without macroscopic separation of the composite films. TGA analysis indicated that the introduction of SiO₂ could improve the thermal stability of the composite films. Dynamic mechanical thermal analysis showed that the composite films with low DDS content (5 wt%) had a higher glass transition temperature (T_g) than pure PI matrix. When the content of DDS was above 10 wt%, the T_g of the composite decreased slightly due to the plasticizing effect of flexible PDPhS linkages on the rigid PI chains. The composite films with high SiO₂ content exhibited higher values of storage modulus. Tensile measurements also showed that the modulus and tensile strength of the composite films increased with increasing SiO₂ content, and the composite films still retained a high elongation at break due the introduction of DDS. The density and water absorption of the composite films were also characterized. Copyright © 2006 Society of Chemical Industry

The natural alkaloid isoanabasine: synthesis from 2,3′-bipyridine, efficient resolution with BINOL, and assignment of absolute configuration by Mosher’s method

Co-reporter:Chuan-Qing Kang, Yan-Qin Cheng, Hai-Quan Guo, Xue-Peng Qiu, Lian-Xun Gao

Tetrahedron: Asymmetry 2005 Volume 16(Issue 12) pp:2141-2147

Publication Date(Web):20 June 2005

DOI:10.1016/j.tetasy.2005.05.012

A highly efficient and practical resolution of racemic 1-benzylisoanabasine, which was synthesized by reduction of the benzyl salt of 2,3′-bipyridine, has been achieved through molecular complexation with (R)-BINOL or (S)-BINOL to afford pure enantiomers (100% ee). The two enantiomers of the natural alkaloid isoanabasine have been obtained by debenzylation of the corresponding enantiomeric 1-benzylisoanabasine. Using Mosher’s method by NMR techniques, the absolute configuration of (−)-isoanabasine has been assigned as the (R)-configuration for the first time. Moreover, an unexpected rotamer ratio of Mosher’s amide was observed. The syn-form of two rotamers of (R)-MTPA-(R)-isoanabasine was predominant over the anti-form.(R)-1-Benzyl-3-(pyridin-2-yl)piperidineC17H20N2Ee = 100%[α]D20=-65.4 (c 2.0, ethanol)Source of chirality: resolutionAbsolute configuration: R(R)-3-(Pyridin-2-yl)piperidineC10H14N2Ee = 100%[α]D20=-15.2 (c 1.0, ethanol)Source of chirality: chiral poolAbsolute configuration: R

Chiral C2-symmetric ligands containing two binaphthyl units linked by 2,2′-bipyridyl bridge in asymmetric catalysis

Co-reporter:Xiao-Li Bai, Chuan-Qing Kang, Xu-Dong Liu, Lian-Xun Gao

Tetrahedron: Asymmetry 2005 Volume 16(Issue 3) pp:727-731

Publication Date(Web):7 February 2005

DOI:10.1016/j.tetasy.2004.12.015

The catalytic activities of new chiral C2-symmetric ligands 1–4 in the asymmetric alkylation of aromatic aldehydes with diethylzinc to give 1-arylpropanols are studied. In most cases, the yields were good and enantioselectivities up to 87% were observed. Copper-catalyzed cyclopropanation proceeded with ⩽51% enantioselectivity and ∼3:1 trans/cis-diastereoselectivity.(R,R)-5,5′-Bis[2,2′-bis(hexyloxy)-1,1′-binaphthalen-6-yl]-2,2′-bipyridineC74H80N2O4[α]D20 = +44 (c 0.1, CH2Cl2)Source of chirality:(R)-BINOLAbsolute configuration:R,R(R,R)-5,5′-Bis[2,2′-diethoxy-1,1′-binaphthalen-6-yl]-2,2′-bipyridineC58H48N2O4[α]D20 = +33 (c 0.1, CH2Cl2)Source of chirality:(R)-BINOLAbsolute configuration:R,R(R,R)-5,5′-Bis[2,2′-dihydroxyl-1,1′-binaphthalen-6-yl]-2,2′-bipyridineC50H32N2O4[α]D20 = +65.4 (c 0.1, THF)Source of chirality:(R)-BINOLAbsolute configuration:R,R(R,R)-6,6′-Bis[2,2′-diethoxy-1,1′-binaphthalen-3-yl]-2,2′-bipyridineC58H48N2O4[α]D20 = +87 (c 0.1, CH2Cl2)Source of chirality:(R)-BINOLAbsolute configuration:R,R(R,R)-6,6′-Bis[2,2′-dihydroxyl-1,1′-binaphthalen-3-yl]-2,2′-bipyridineC50H32N2O4[α]D20 = +309 (c 0.1, THF)Source of chirality:(R)-BINOLAbsolute configuration:R,R(R,R)-5,5′-Bis[2,2′-diethoxy-1,1′-binaphthalen-3-yl]-2,2′-bipyridineC58H48N2O4[α]D20 = +94 (c 0.1, CH2Cl2)Source of chirality: (R)-BINOLAbsolute configuration: R,R(R,R)-6,6′-Bis[2,2′-bis(hexyloxy)-1,1′-binaphthalen-6-yl]-2,2′-bipyridineC74H80N2O4[α]D20 = +41 (c 0.1, CH2Cl2)Source of chirality: (R)-BINOLAbsolute configuration: R,R(R,R)-6,6′-Bis[2,2′-diethoxy-1,1′-binaphthalen-6-yl]-2,2′-bipyridineC58H48N2O4[α]D20 = +11 (c 0.1, CH2Cl2)Source of chirality: (R)-BINOLAbsolute configuration: R,R(R,R)-6,6′-Bis[2,2′-dihydroxyl-1,1′-binaphthalen-6-yl]-2,2′-bipyridineC50H32N2O4[α]D20 = +94 (c 0.1, THF) Source of chirality: (R)-BINOLAbsolute configuration: R,R

Synthesis and chirooptical properties of optically active poly(ester imide)s based on axially asymmetric 1,1′-binaphthyls

Co-reporter:Naiheng Song;Wei Qi;Xuepeng Qiu;Mengxian Ding

Journal of Polymer Science Part A: Polymer Chemistry 2004 Volume 42(Issue 17) pp:4318-4326

Publication Date(Web):26 JUL 2004

DOI:10.1002/pola.20297

A series of optically active poly(ester imide)s (PEsI's) has been synthesized by the polycondensation reactions of new axially asymmetric dianhydrides, that is, (R)-2,2′-bis(3,4-dicarboxybenzoyloxy)-1,1′-binaphthyl dianhydride and (S)-2,2′-bis(3,4-dicarboxybenzoyloxy)-1,1′-binaphthyl dianhydride, and various diamines with aromatic, semiaromatic, and aliphatic structures. The polymers have inherent viscosities of 0.45–0.70 dL/g, very good solubility in common organic solvents, glass-transition temperatures of 124–290 °C, and good thermal stability. Wide-angle X-ray crystallography of these polymers shows no crystal diffraction. In comparison with model compounds, an enhanced optical rotatory power has been observed for the repeat unit of optically active PEsI's based on aromatic diamines, and it has been attributed to a collaborative asymmetric perturbation of chiral 1,1′-binaphthyls along the rigid backbones. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4318–4326, 2004

Self-discriminating and hierarchical assembly of racemic binaphthyl-bisbipyridines and silver ions: from metallocycles to gel nanofibers

Co-reporter:Yabing He, Zheng Bian, Chuanqing Kang and Lianxun Gao

Chemical Communications 2011 - vol. 47(Issue 5) pp:NaN1591-1591

Publication Date(Web):2010/11/29

DOI:10.1039/C0CC03192E

An organogel formed from a cyclic β-aminoalcohol

Co-reporter:Chuanqing Kang, Zheng Bian, Yabing He, Fushe Han, Xuepeng Qiu and Lianxun Gao

Chemical Communications 2011 - vol. 47(Issue 38) pp:NaN10748-10748

Publication Date(Web):2011/08/24

DOI:10.1039/C1CC13179F

A new organogelator with unique structural feature of a cyclic β-aminoalcohol is presented as the first example of gelation by aminoalcohol through hydrogen-bonding between hydroxy and amine.

Stereoselective and hierarchical self-assembly from nanotubular homochiral helical coordination polymers to supramolecular gels

Co-reporter:Yabing He, Zheng Bian, Chuanqing Kang and Lianxun Gao

Chemical Communications 2010 - vol. 46(Issue 31) pp:NaN5697-5697

Publication Date(Web):2010/07/01

DOI:10.1039/C0CC01433H

ZIF-8 crystal coatings on a polyimide substrate and their catalytic behaviours for the Knoevenagel reaction

Co-reporter:Rizhe Jin, Zheng Bian, Jizhen Li, Mengxian Ding and Lianxun Gao

Dalton Transactions 2013 - vol. 42(Issue 11) pp:NaN3940-3940

Publication Date(Web):2012/12/11

DOI:10.1039/C2DT32161K

Chiral binaphthylbisbipyridine-based copper(I) coordination polymer gels as supramolecular catalysts

Co-reporter:Yabing He, Zheng Bian, Chuanqing Kang, Yanqin Cheng and Lianxun Gao

Chemical Communications 2010 - vol. 46(Issue 20) pp:NaN3534-3534

Publication Date(Web):2010/03/29

DOI:10.1039/B926936C

A novel class of chiral coordination polymer organogels, with multi–stimuli responsive properties and suitable for use as catalysts in 1,3-dipolar Huisgen cycloaddition reaction, are reported.