Jian-she Hu

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Name: Hu Jianshe; 胡建设

Organization: Northeastern University

Department: Center for Molecular Science and Engineering, College of Science

Title:

TOPICS

Organic Chemistry

Liquid Crystal

Chemicals
References

New amphiphilic polycarbonates with side functionalized cholesteryl groups as biomesogenic units: synthesis, structure and liquid crystal behavior

Co-reporter:Xiaoxu Xu;Xiaofeng Liu;Qun Li;Jianshe Hu;Qifan Chen;Liqun Yang;Yanhua Lu

RSC Advances (2011-Present) 2017 vol. 7(Issue 23) pp:14176-14185

Publication Date(Web):2017/02/28

DOI:10.1039/C7RA00360A

The synthesis of four new amphipathic copolymers with side functionalized-cholesterol based aliphatic polycarbonates is described through the ring-opening polymerization and coupling reaction. The chemical structures, liquid crystal (LC) behavior, and thermal stability of the chiral monomers and copolymers obtained in this study were characterized using Fourier transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, gel permeation chromatography (GPC), polarizing optical microscopy (POM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) measurements. The effect of the spacer length on the molecular interaction and mesophase of the chiral monomers and copolymers was investigated. It was found that chiral monomers with longer spacer seemed beneficial for the formation of mesophases, and the additional ordering on polymerization caused mesophases to be more ordered than for the corresponding monomers. The LC copolymers all revealed a smectic A phase with an interdigitated molecular arrangement. The results seemed to show a decreased tendency toward the glass transition temperature, and isotropic temperature for the LC copolymers by increasing the spacer length. In addition, four LC copolymers had a good thermal stability.

Study on the structure, melting, and nonisothermal crystallization behaviors of isotactic polypropylene with nematic liquid crystalline polymer as a new β-nucleating agent

Co-reporter:Sheng Lu;Yan-Hua Lu;Jing Sun

Polymer Science, Series A 2015 Volume 57( Issue 1) pp:67-75

Publication Date(Web):2015 January

DOI:10.1134/S0965545X15010058

Wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) were used to evaluate the effect of nematic liquid crystalline polymer as a new β-nucleating agent (LCP-NA) on the structure, melting, and nonisothermal crystallization behaviors of isotactic polypropylene (iPP). A high content of β-crystal could be obtained by the combined effect of the optimum LCP-NA content and crystallization temperature and time. The relative content of β-crystal increased with increasing LCP-NA content, reached a maximum value of 59% when LCP-NA content was 1.0 wt % at 130°C for 1h, and then decreased with a further increase of LCP-NA content. Avrami, Jeziorny, Ozawa, and Mo methods were applied to describe the crystallization process. Jeziorny and Mo methods showed a good agreement in describing the nonisothermal crystallization behaviors of pure iPP and iPP blends with 1.0 wt % LCP-NA, but Ozawa method could not better describe these behaviors. The addition of LCP-NA could effectively increase the crystallization temperature and the crystallization rate, and induce heterogeneous nucleation with the nonisothermal tridimensional growth of the spherulite. Kissinger’s method indicated that the iPP blends with 1.0 wt % LCP-NA needed a higher energy for crystallization per mole than pure iPP.

Influence of two liquid crystalline polysiloxanes with different average molecular weight as new β-nucleator on crystallization structure of isotactic polypropylene

Co-reporter:Jing Sun;Qun Li;Xi-Jing Yao;Yang Qi

Polymer Bulletin 2013 Volume 70( Issue 9) pp:2519-2530

Publication Date(Web):2013 September

DOI:10.1007/s00289-013-0969-1

Two liquid crystalline polymers (LC-N1 and LC-N2) with different average molecular weight were designed and synthesized as a new β-nucleator in isotactic polypropylene (iPP). The main aim of this work was to investigate the influence of LC-N1 and LC-N2 on the crystallization structure and β nucleating activity of the iPP with wide angle X-ray diffraction and polarized optical microscopy. The β nucleation activity not only depended on the nucleator content, mesogenic molecular structure, and thermal processing history, but also on average molecular weight of the liquid crystalline polymers. LC-N1 or LC-N2 has been found to be an effective β-nucleator for the iPP. The experimental results indicated the relative content of β-crystal first increased and then decreased with increasing the nucleator content or crystallization temperature. The addition of LC-N1 or LC-N2 could provide a large number of nuclei, enhance the crystallization rate, reduce the spherulite size, and lead to a more uniform morphology; moreover, the colorful β-crystal was also induced. In addition, LC-N2 with higher average molecular weight is more effective than LC-N1 in inducing β heterogeneous nucleation under same crystallization conditions.

A nematic liquid crystalline polymer as highly active novel β-nucleating agent for isotactic polypropylene

Co-reporter:Jing Sun;Qun Li;Xi-Jing Yao;Yang Qi

Journal of Materials Science 2013 Volume 48( Issue 11) pp:4032-4040

Publication Date(Web):2013 June

DOI:10.1007/s10853-013-7215-y

A nematic liquid crystalline polysiloxane has been found to be a novel nucleating agent (LCP-NA2) to induce the formation of β-crystals in isotactic polypropylene (iPP). Wide angle X-ray diffraction, differential scanning calorimetry, and polarized optical microscopy were used to evaluate the nucleating activity of LCP-NA2. The effect of LCP-NA2 content, crystallization temperature, and time on the crystallization structure, morphology, and thermal behavior of the iPP was discussed. The results indicated that the nucleating activity mainly depended on LCP-NA2 content and thermal history of processing. The addition of LCP-NA2 could provide a large number of nuclei and lead to a more uniform morphology, along with a change in the nucleation and crystal growth mechanism. The relative content of β-crystal increased with increasing LCP-NA2 content or crystallization temperature, reached a maximum value of 70 % when LCP-NA2 content and crystallization temperature were 1.0 wt% and 125 °C, and then decreased with a further increase of LCP-NA2 content or crystallization temperature. In addition, a different polymorphic behavior had been observed between pure iPP and LCP-NA2/iPP blends under the same thermal treatment.

Cholesteric monomer and elastomers containing menthyl groups: Synthesis and phase behavior

Co-reporter:Jian-She Hu;Dan Li;Qing-Bao Meng ;Dan-Shu Yao

Journal of Applied Polymer Science 2012 Volume 125( Issue 5) pp:3849-3855

Publication Date(Web):

DOI:10.1002/app.36701

Abstract

The synthesis of a new cholesteric monomer (M_LC) containing menthyl groups and a series of cholesteric elastomers (LCE₁−LCE₄) is described. Their chemical structures and purity were characterized by FTIR, ¹H-NMR, and elemental analyses. The phase behavior and thermal stability were investigated by differential scanning calorimetry, polarizing optical microscopy, X-ray diffraction, and thermogravimetric analysis. By inserting a flexible spacer between the mesogenic core and the terminal menthyl groups, mesomorphism of M_LC was realized. LCE₁−LCE₄ with low content of crosslinking unit exhibited cholesteric phase because of the introduction of the nematic crosslinking unit. This indicates that low levels of chemical crosslinking do not significantly affect the phase behavior and mesomorphism of the elastomers, and reversible mesophase transitions can be observed. In addition, with increasing the content of crosslinking unit, the corresponding T_g decreased for LCE₁−LCE₄, whereas their T_i did not remarkable change. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Liquid crystalline properties of cholesteric elastomers based on a mesogenic monomer containing menthyl groups

Co-reporter:Jian-She Hu;Xia Zhang;Dan Li ;Qing-Bao Meng

Polymer International 2012 Volume 61( Issue 7) pp:1186-1192

Publication Date(Web):

DOI:10.1002/pi.4198

Abstract

A new chiral mesogenic monomer (M_LC) based on menthyl groups and the corresponding cholesteric elastomers (LCE₁–LCE₃) were prepared. Their chemical structures and purity were characterized by Fourier transform infrared, nuclear magnetic resonance and elemental analyses. The liquid crystalline properties were investigated by differential scanning calorimetry, polarizing optical microscopy, thermogravimetric analysis and X-ray diffraction. The selective reflection of light for M_LC was characterized with ultraviolet/visible/near infrared. The effect of the content of crosslinking units on the liquid crystalline behaviour of LCE₁–LCE₃ is discussed. The experimental results show that the chiral monomer and the corresponding elastomers containing menthyl groups can show mesomorphism when a flexible linkage chain is inserted between the mesogenic core and the bulky terminal menthyl fragments to reduce the steric effect. M_LC exhibited a chiral smectic C phase, a cholesteric phase and a cubic blue phase. LCE₁–LCE₃ with a low content of crosslinking units showed a cholesteric phase because of the introduction of the nematic crosslinking unit. With increasing content of crosslinking units, the corresponding glass transition temperature increased, while the clearing temperature decreased. Thermogravimetric analysis showed that LCE₁–LCE₃ have good thermal stability. Copyright © 2012 Society of Chemical Industry

Synthesis, structure, and properties of chiral liquid crystal monomers and polymers based on menthol

Co-reporter:Jian-She Hu;Dan Li;Wen-Chang Zhang ;Qing-Bao Meng

Journal of Polymer Science Part A: Polymer Chemistry 2012 Volume 50( Issue 24) pp:5049-5059

Publication Date(Web):

DOI:10.1002/pola.26350

Abstract

To study structure–mesomorphism relationships of the monomers and polymers based on menthol, four new chiral monomers (M₁–M₄) and the corresponding homopolymers (P₁–P₄) with menthyl group were synthesized. Their chemical structures, formula, phase behavior, and thermal stability were characterized by FTIR, ¹H NMR, ¹³C NMR, elemental analyses, differential scanning calorimetry, polarizing optical microscopy, X-ray diffraction, and thermogravimetric analysis. The selective reflection of light was investigated with ultraviolet/visible spectrometer. The influence of the mesogenic core rigidity, spacer length, and menthyl steric effect on the mesomorphism of M₁–M₄ and P₁–P₄ was examined. By inserting a flexible spacer between the mesogenic core and the terminal menthyl groups, four target monomers and polymers could form the expected mesophase. Moreover, their melting temperature (T_m), glass transition temperature (T_g), clearing temperature (T_i), and mesophase range (ΔT) increased with increasing the mesogenic core rigidity; whereas the T_m and T_g decreased, T_i and ΔT increased with an increase of the spacer length. M₁ and M₂ showed monotropic and enantiotropic cholesteric phase, respectively, whereas M₃ and M₄ all revealed chiral smectic C (SmC*), cholesteric and cubic blue phases. In addition, with increasing temperature, the selective reflection of light shifted to the long wavelength region at the SmC* phase range and to the short wavelength region at the cholesteric range, respectively. P₁ and P₂ only showed a smectic A (SmA) phase, whereas P₃ and P₄ exhibited the SmC* and SmA phases. All the obtained polymers had very good thermal stability. © 2012 Wiley Periodicals, Inc. J. Polym. Sci. Part A: Polym Chem, 2012

Synthesis, structure and mesomorphism of new cholesteric monomers and smectic comblike polymers

Co-reporter:Jian-She Hu, Bai Wang, Cong Liu, Xiao-Zhi He

European Polymer Journal 2010 Volume 46(Issue 3) pp:535-545

Publication Date(Web):March 2010

DOI:10.1016/j.eurpolymj.2009.12.002

Seven new cholesteric monomers (M-1−M-7) and the corresponding smectic comblike polymers containing cholesteryl groups (P-1−P-7) were synthesized. The chemical structures and purity were characterized by FT-IR, 1H NMR, and elemental analyses. The specific optical rotations were evaluated with a polarimeter. The mesomorphism was investigated by polarizing optical microscopy, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction. The specific optical rotation values of these monomers and polymers with the same numbers of phenyl ring and terminal groups were nearly equal, however, they decreased with increasing the aryl numbers in the mesogenic core. M-1−M-7 showed oily streak texture and focal conic texture, or fingerprint texture, or spiral texture of cholesteric phase. P-1−P-7 showed the smectic A phase. The melting, clearing, and glass transition temperatures increased, and the mesophase temperature ranges widened with increasing the aryl number in the mesogenic core. Surprisingly, although the molecular structures of M-6 and M-7 were similar to those of M-4, namely the mesogenic cores contained three phenyl rings, their phase behavior had a considerable difference, and Tm and Ti of M-6 and M-7 were less than those of M-4. In addition, M-6 and M-7 also showed an obvious glass transition. TGA showed that all the polymers had good thermal stabilities.Seven new cholesteric monomers (M-1–M-7) and the corresponding smectic comblike polymers containing cholesteryl groups (P-1–P-7) were synthesized. The chemical structures and purity were characterized by FT-IR, 1H NMR, and elemental analyses. The mesomorphism was investigated by POM, DSC, TGA, and XRD. The structure–property relationships of these chiral monomers and polymers are discussed. M-1–M-7 showed oily streak texture and focal conic texture, or fingerprint texture, or spiral texture of cholesteric phase. P-1–P-7 showed the smectic A phase. TGA showed that all the polymers had good thermal stabilities.

Influence of different nematic crosslinking unit on mesomorphism of side-chain cholesteric elastomers containing menthyl groups

Co-reporter:Jian-She Hu;Zhi-Wei Song;Cong Liu;Wen-Chang Zhang

Colloid and Polymer Science 2010 Volume 288( Issue 8) pp:851-858

Publication Date(Web):2010 June

DOI:10.1007/s00396-010-2206-x

The synthesis of two cholesteric monomers (M1 and M2), nematic crosslinking agent (C1 and C2), and the corresponding side-chain elastomers containing menthyl groups (P1 and P2 series) is described. The mesomorphism was investigated by differential scanning calorimetry, polarizing optical microscopy, X-ray diffraction, and thermogravimetric analysis. The effect of the content of the different nematic crosslinking unit on the mesomorphism of the elastomers was discussed. M1 and M2 showed cholesteric and blue phases; C1 and C2 showed nematic phase. Because of the introduction of the nematic crosslinking unit, elastomers P1-1−P1-5 and P2-1−P2-5 exhibited cholesteric phase. With increasing the content of nematic crosslinking unit, Tg of the obtained elastomers revealed an increased tendency, and Ti of P1 series firstly increased then decreased, while Ti of P2 series decreased the mesomorphism of the corresponding elastomers when the content of nematic crosslinking unit was 12 mol.%.

Synthesis and properties of new chiral mesogenic monomers and side-chain smectic homopolymers containing (−)-menthyl groups

Co-reporter:Jian-She Hu, Cong Liu, Xia Zhang, Qing-Bao Meng

European Polymer Journal 2009 Volume 45(Issue 11) pp:3292-3301

Publication Date(Web):November 2009

DOI:10.1016/j.eurpolymj.2009.07.015

The synthesis of new chiral monomers (M1−M5) and the corresponding smectic homopolymers (P1−P5) containing menthyl groups is described. The chemical structures and purity were characterized by FT-IR, 1H NMR and elemental analyses. The specific optical rotations were evaluated with a polarimeter. The phase behavior and mesomorphism were investigated by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X-ray diffraction. The selective reflection property of light was studied with UV/visible/NIR. The monomers M2−M5 formed a chiral smectic C (SC∗), and cholesteric or blue phase when a flexible linkage chain was inserted between the mesogenic core and the terminal menthyl groups by reducing the steric effect. M1 showed no mesomorphism, while M2−M5 showed enantiotropic SC∗ and cholesteric phases. Moreover, M5 also exhibited a cubic blue phase on cooling. With increasing temperature, the selective reflection of light shifted to the long wavelength region at the SC∗ phase range, and to the short wavelength region at the cholesteric phase range, respectively. The homopolymers P1−P5 all exhibited the batonnet textures of a smectic A phase. The melting, clearing, and glass transition temperatures increased, and the mesophase temperature ranges widened with increasing the aryl number in the mesogenic core.The new chiral monomers M2−M5 can form SC∗, and cholesteric or blue phases when a flexible spacer is inserted between the mesogenic core and the terminal menthyl groups by reducing the steric effect, while their corresponding homopolymers P1−P5 only exhibit SA phases. Tm, Ti and Tg increased with increasing the rigidity of mesogenic units or decreasing the spacer length. With increasing temperature, the selective reflection of light shifted to the long wavelength region at the SC∗ phase range, and to the short wavelength region at the cholesteric phase range, respectively.

Synthesis and characterization of new cholesteric monomers and smectic polymers containing menthyl groups

Co-reporter:Jian-She Hu;Zhan-Xiang Zhao;Bo Kong;Dan Li

Colloid and Polymer Science 2009 Volume 287( Issue 2) pp:215-224

Publication Date(Web):2009 February

DOI:10.1007/s00396-008-1970-3

New cholesteric monomers (M2−M5) and the corresponding smectic homopolymers (P2−P5) based on menthyl groups were synthesized. The chemical structures were characterized by Fourier transform infrared and 1H NMR. The specific optical rotations were evaluated with a polarimeter. The structure–property relationships of the new compounds are discussed. The mesomorphism was investigated by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X-ray diffraction. The selective reflection property of light was studied with UV/Visible/NIR. The monomers M2−M5 formed the cholesteric or blue phase when a flexible link chain was inserted between the mesogenic core and the terminal menthyl groups by reducing the steric effect. M1 showed no mesomorphism, while M2−M5 revealed enantiotropic cholesteric phase. In addition, M2 and M3 also showed a cubic blue phase on cooling. The selective reflection of light for M2−M5 shifted to the short reciprocal wavelength region with increasing the temperature or intramolecular spacer length. P2−P5 exhibited the smectic A phase. The melting, clearing, and glass transition temperatures increased when increasing the aryl number in the mesogenic core or decreasing the intramolecular spacer length.