Yong Wu

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Organization: Sichuan University

Department: College of Chemical Engineering

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Polymer

Stimuli Responsive Polymers Stimuli Responsive Polymers Photo Responsive Polymers

Organic Chemistry

Liquid Crystal

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References

A unidomain membrane prepared from liquid-crystalline poly(pyridinium 4-styrene sulfonate) for anhydrous proton conduction

Co-reporter:Xiaohui Yang, Shuai Tan, Ting Liang, Bingzhuo Wei, Yong Wu

Journal of Membrane Science 2017 Volume 523() pp:355-360

Publication Date(Web):1 February 2017

DOI:10.1016/j.memsci.2016.10.010

•Smectic liquid crystal poly(pyridinium 4-styrene sulfonate) was synthesized.•A solution-cast membrane was prepared from the liquid crystal polymer.•A unidomain architecture was obtained by shearing the smectic membrane.•The uniformly aligned smectic bilayers in the membrane enhanced proton conduction.Liquid-crystalline poly(pyridinium 4-styrene sulfonate) was synthesized through an acid-base reaction between poly(4-styrene sulfonic acid) and a mesomorphic pyridine derivative. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) measurements revealed that the resultant polymer exhibited a bilayer smectic order with a d-spacing of 10.2 nm at temperatures above 193 °C. Thermogravimetric (TG) analysis indicated that the polymer was thermally stable at temperatures up to288 °C. A solution-cast membrane of the polymer was mechanically sheared in the smectic A phase to obtain a unidomain membrane with a thickness of 0.15 mm. Polarizing optical microscope (POM) and scanning electron microscope (SEM) images confirmed that the smectic bilayers in the unidomain membrane were perpendicularly to the shearing direction. Electrochemical characterization suggested that the uniformly lamellar pathways formed in the uni-domain membrane favored anhydrous proton conduction. The maximum proton transference number and conductivity of the membrane reached 0.46 and 7.0×10−6 S cm−1, respectively. The temperature dependence of the proton conductivity followed the Arrhenius law and the estimated activation energy for the anhydrous proton conduction across the membrane was 60 kJ mol−1.A unidomain membrane was prepared by shearing liquid crystal poly(pyridinium 4-styrene sulfonate) in the smectic A phase. The uniformly aligned lamellar architecture enhanced anhydrous proton conduction of the protic salt membrane.

Synthesis, structural and electrochemical characterization of benzimidazole compounds exhibiting a smectic C liquid crystal phase

Co-reporter:Bingzhuo Wei, Shuai Tan, Ting Liang, Siyu Cao, Yong Wu

Journal of Molecular Structure 2017 Volume 1133() pp:392-397

Publication Date(Web):5 April 2017

DOI:10.1016/j.molstruc.2016.12.042

•Mesomorphic benzimidazole compounds were synthesized.•Partially interdigitated smectic C (SC) bilayers were formed.•Lamellar hydrogen bonding networks developed in the SC phase.•The SC phase favored anhydrous proton conduction.Mesomorphic benzimidazole compounds were prepared from a biphenyl benzoate based precursor by substitution reaction of alkyl bromide with 2-mercaptobenzimidazole. Molecular structures of the benzimidazole compounds were characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy and elemental analysis. Differential scanning calorimetry (DSC) measurements and polarizing optical microscopic (POM) observations revealed that the benzimidazole compounds exhibited a thermotropic smectic C (SC) phase. Temperature dependent X-ray diffraction (XRD) patterns suggested a tilted bilayer smectic structure in which intermolecular hydrogen bonds between benzimidazole moieties formed lamellar arrangement. Electrochemical impedance spectroscopy (EIS) characterization suggested that the SC phase favored anhydrous proton conduction of the benzimidazole compounds and the proton conductivities showed an Arrhenius temperature dependence.Lamellar arrangement of intermolecular hydrogen bonds between benzimidazole moieties was achieved in benzimidazole compounds exhibiting a smectic C phase. EIS characterization revealed that the smectic C phase favored anhydrous proton conduction.

Synthesis and characterization of proton conductive liquid crystals bearing phosphonic acid moieties

Co-reporter:Ting Liang, Shuai Tan, Siyu Cao, Yong Wu

Journal of Molecular Structure 2017 Volume 1150(Volume 1150) pp:

Publication Date(Web):15 December 2017

DOI:10.1016/j.molstruc.2017.09.032

•Mesomorphic phosphonic acid derivatives were synthesized.•The derivatives exhibited smectic A and nematic phases.•A bilayer structure formed in the smectic A phase.•The liquid crystal phases favored proton conduction.A homologous series of mesogenic phosphonic acid derivatives (CnPA) were synthesized through the Michaelis-Becker reaction. Chemical structures of the derivatives were characterized by nuclear magnetic resonance, Fourier transform infrared spectroscopy and high-resolution mass spectrometry. Differential scanning calorimetry measurements and polarizing optical microscopic observations indicated that CnPA exhibited smectic A and nematic phases at intermediate temperatures (119–196 °C). Temperature-dependent X-ray diffraction measurements suggested that smectic CnPA formed a bilayer architecture in which phosphonic acid moieties aggregated into lamellar arrays. Electrochemical impedance spectrum measurements using indium tin oxide (ITO) electrodes revealed that the liquid crystal phases favored anhydrous proton conduction of the phosphonic acid derivatives and the proton conductivities on the order of 10−4 S cm−1 were achieved.The mesomorphic phosphonic acid derivatives exhibit thermostropic smectic A and nematic phases. The bilayer semctic order of the phosphonic acids favored anhydrous proton conduction.Download high-res image (160KB)Download full-size image

Proton conductive polymers obtained by in-situ polymerization of a mesomorphic benzimidazole monomer in smectic A, nematic and isotropic phases

Co-reporter:Shuai Tan, Ting Liang, Bingzhuo Wei, Siyu Cao, Yong Wu

Reactive and Functional Polymers 2017 Volume 115(Volume 115) pp:

Publication Date(Web):1 June 2017

DOI:10.1016/j.reactfunctpolym.2017.04.012

Side-chain polymers with different microstructures have been prepared by in-situ ultra-violet (UV) photopolymerization of a liquid crystal monomer bearing a terminal benzimidazole moiety. The molecular weights of PBIS, PBIN, and PBII obtained from the smectic A (SA), nematic and isotropic liquid phases were 1.53, 1.40 and 1.38 × 104 g mol− 1, respectively. In-situ UV polymerization of the monomer aligned by mechanical shearing in the SA phase resulted in a macroscopically layered polymer PBIalS. PBIalS exhibited higher glass transition temperature than PBIS, PBIN, and PBII. Electrochemical impedance spectroscopy (EIS) measurements suggested the anhydrous proton conductivity of PBIalS parallel to the aligned layers was more than one order of magnitude higher than those of PBIS, PBIN and PBII. At the same temperature, proton conductivity of PBIS was higher than those of PBIN and PBII. The results suggested that the architecture of the benzimidazole polymer, which could be tuned by the mesomorphases of the monomer, had a profound impact on the anhydrous proton conduction.

Anhydrous proton conduction in liquid crystals containing benzimidazole moieties

Co-reporter:Shuai Tan, Bingzhuo Wei, Ting Liang, Xiaohui Yang and Yong Wu

RSC Advances 2016 vol. 6(Issue 40) pp:34038-34042

Publication Date(Web):30 Mar 2016

DOI:10.1039/C6RA03375J

A homologous series of biphenyl benzoate-based compounds with an alkthio chain bearing a benzimidazole moiety at the termini was synthesized by a nucleophilic substitution reaction. The compounds exhibited smectic A and nematic phases over a temperature range of 173–116 °C during the cooling process. A partially interdigitated bilayer order developed in the smectic assemblies and hydrogen-bonding between the benzimidazole moieties extended along the plane parallel to the smectic layer. Electrochemical characterization revealed that the liquid crystal phases favoured anhydrous proton conduction in the benzimidazole compounds and a proton conductivity of 4.4 × 10−5 S cm−1 was achieved at 173 °C. The temperature dependence of the proton conductivities approximately followed the Arrhenius law and the proton conduction in the benzimidazole liquid crystals was assumed to be dominated by the proton hopping mechanism.

Synthesis, characterization, and electrochemical properties of smectic pyridinium salts with inorganic dihydrogen phosphate ions

Co-reporter:Xiaohui Yang;Shuai Tan;Ting Liang;Bingzhuo Wei

Ionics 2016 Volume 22( Issue 1) pp:85-92

Publication Date(Web):2016 January

DOI:10.1007/s11581-015-1524-x

Pyridinium salts with inorganic dihydrogen phosphate ions (CnPy-DHP) were derived from biphenyl benzoate-based precursors bearing terminal alkoxy chains. Molecular structures of the pyridinium salts were characterized by 31P magic-angle spinning nuclear magnetic resonance (31P MAS NMR) spectroscopy, elemental analysis, and Fourier transform infrared (FT-IR) spectroscopy. Differential scanning calorimetry (DSC) measurements and polarizing optical microscopic (POM) observations indicated that the pyridinium salts exhibited smectic A (SA) phase at intermediate temperatures (above 159 °C). X-ray diffraction (XRD) measurements suggested that the pyridinium salts formed a bilayer structure with head-to-head configuration in the SA phase. Electrochemical impedance spectrum (EIS) measurements using indium tin oxide (ITO) electrodes showed that ionic conductivities of the pyridinium salts increased with the decrease in length of alkoxy chains and approached 7.0 × 10−5 S/cm in the SA phase. Wagner’s DC polarization measurements using manganese (IV) oxide (MnO2) electrodes confirmed the presence of proton conduction in the pyridinium salts. The steady state currents resulted from DC polarization revealed that the SA phase favored proton conduction. The temperature dependence of the ionic conductivity followed Arrhenius law, and the proton transport in the SA phase was supposed to occur by hopping of dissociated protons along layered pathways formed by pyridinium cations and dihydrogen phosphate ions.

Conductive imidazolium side chain liquid crystal polyacrylates prepared from postpolymerization functionalization

Co-reporter:Caihong Wang;Shuai Tan;Ting Liang ;Xiaohui Yang

Journal of Applied Polymer Science 2015 Volume 132( Issue 9) pp:

Publication Date(Web):

DOI:10.1002/app.41564

ABSTRACT

Hydroxide and tetrafluoroborate salts of imidazolium polyacrylates have been prepared from postpolymerization functionalization of a brominated precursor containing mesogenic side chains followed by anion exchange. The ionic polyacrylates possessed molecular weights in the range 1.1–1.3 × 10⁴ g·mol⁻¹. Differential scanning calorimetry measurements and polarizing optical microscope observation indicated that the resultant ionic polyacrylates exhibited smectic C and A liquid crystal phases over a temperature range of about 60°C. Electrochemical impedance spectroscopy measurements show that ionic conductivities of the hydroxide salt were much higher than those of the tetrafluoroborate salt for the imidazolium polyacrylates at the same temperature. The maximum ionic conductivity of the random hydroxide salt of imidazolium polyacrylate in the smectic A phase reached 4.45 × 10⁻² S·cm⁻¹. The ionic polyacrylates were successfully aligned by mechanical shearing in the smectic A phase. Ionic conductivities of the sheared samples were more than 1 order of magnitude higher than those of the random samples in the solid state. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41564.

Kinetic modeling of anhydrous proton conduction in side chain liquid crystal polyacrylates

Co-reporter:Shuai Tan, Yong Wu, Ting Liang, Xiaohui Yang

International Journal of Hydrogen Energy 2014 Volume 39(Issue 30) pp:17391-17397

Publication Date(Web):13 October 2014

DOI:10.1016/j.ijhydene.2014.08.043

•Proton conductivities of mesomorphic sulfonated polyacrylates were characterized.•A modified Arrhenius equation modeled the effect of mesophase on conduction.•Kinetic parameters in the mesophases were obtained from least-squares regression.•The inherent conductivity in smectic A was higher than that in nematic phase.Mesomorphic polyacrylates with different degree of sulfonation (DS) in side chains were synthesized by post polymerization functionalization. The sulfonated polymer exhibited thermotropic smectic A (SA) and/or nematic (N) phases when DS was 0.2–0.4. The temperature-dependent anhydrous proton conductivities of the polymers depended on both ion exchange capacity (IEC) and phase type. A modified Arrhenius equation containing IEC and phase coefficient M simultaneously was proposed to model the conduction behavior. Least-squares regression analysis on the kinetic parameters quantitatively revealed proton conduction characteristics in different liquid crystal phases. The activation energies for proton transportation in the SA, N, and isotropic states were 106, 95 and 44 kJ mol−1, respectively. The inherent conductivities per unit IEC in the SA, N, and isotropic states were 8.5 × 108, 5.3 × 107 and 77 S cm−1, respectively. The enhancement of anhydrous proton conduction in liquid crystal phases was ascribed to the increased conducting pathways induced by ordered molecular arrangements.Anhydrous proton conduction in mesomorphic sulfonated polyacrylates was modeled by a modified Arrhenius equation. The inherent conductivity in the smectic A phase was higher than that in the nematic phase.

Anhydrous proton-conducting electrolyte based on a nematic poly(methyl acrylate) containing sulfonated side chains

Co-reporter:Ting Liang;Shuai Tan ;Caihong Wang

Journal of Applied Polymer Science 2014 Volume 131( Issue 12) pp:

Publication Date(Web):

DOI:10.1002/app.40382

ABSTRACT

A nematic poly(methyl acrylate) containing terminal sulfonic acids in side chains was prepared by etherification of a brominated mesomorphic precursor with 2-hydroxyethanesulfonic acid sodium salt. Differential scanning calorimetry measurements and polarized light microscopy observation revealed that the sulfonated polymer exhibited the nematic mesophase at medium temperatures (189–227°C). Electrochemical impedance spectroscopy measurements showed that temperature dependence of anhydrous proton conductivity for the nematic polymer followed the Arrhenius law and that the estimated activation energy was 95 kJ mol⁻¹ in the nematic phase. The proton conductivities of the nematic polymer were two orders of magnitude higher than those of anhydrous Nafion®117 membrane at the same temperature. The enhanced anhydrous proton conductivities of the polymeric electrolyte were ascribed to the orientational order and fluidity of the nematic liquid crystal. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40382.

Anisotropic assembly of a side chain liquid crystal polymer containing sulfoalkoxy groups for anhydrous proton conduction

Co-reporter:Shuai Tan, Caihong Wang and Yong Wu

Journal of Materials Chemistry A 2013 vol. 1(Issue 4) pp:1022-1025

Publication Date(Web):23 Nov 2012

DOI:10.1039/C2TA00925K

A side chain liquid crystal polymer containing pendant sulfonic acid groups has been synthesized by post-polymerization functionalization of a brominated mesogenic precursor. A macroscopic alignment was achieved by mechanical shearing of the liquid crystal polymer in the smectic phase. The uniaxial layered assembly exhibited anisotropic proton conductivities under anhydrous conditions and has potential applications in medium temperature fuel cells.

Syntheses, characterizations and electrochemical properties of mesomorphic 4-(4′-alkoxy-(1,1′-biphenyl)-4-oxy)butane-1-sulfonic acids

Co-reporter:Shuai Tan, Caihong Wang, Ting Liang, Weixing Huang, Yong Wu

Journal of Molecular Structure 2013 Volume 1045() pp:15-19

Publication Date(Web):6 August 2013

DOI:10.1016/j.molstruc.2013.04.037

•Smectic sulfonic derivatives were synthesized and characterized.•Sulfonic acid moieties formed a head-to-head configuration in the smectic phase.•Lamellar sulfonic acid pathways contributed greatly to the anhydrous proton conduction.•Anhydrous proton conductivities in the smectic sulfonic derivatives followed the Arrhenius law.Biphenyl based sulfonic acid derivatives have been synthesized for anhydrous proton conduction. The terminal sulfonic acid moiety was attached to a biphenyl core by ring-opening reaction of 1,4-butane sultone. The target compounds exhibited smectic phases in a temperature range of 180–220 °C. Polarizing optical microscopic observation and temperature dependent X-ray diffraction measurements suggested that sulfonic acid moieties formed a head-to-head configuration in the smectic assemblies. The mesomorphic sulfonic acid derivatives formed lamellar proton conducting pathways and the anhydrous proton conductivities determined by electrochemical impedance spectroscopy showed Arrhenius temperature dependence in the smectic phase.

Anisotropic assembly of a side chain liquid crystal polymer containing sulfoalkoxy groups for anhydrous proton conduction

Co-reporter:Shuai Tan, Caihong Wang and Yong Wu

Journal of Materials Chemistry A 2013 - vol. 1(Issue 4) pp:NaN1025-1025

Publication Date(Web):2012/11/23

DOI:10.1039/C2TA00925K