Optical Properties and Liquid-Crystalline Behaviors of Cyclosiloxane-Based Oligomer Films

2011 ◽  
Vol 391-392 ◽  
pp. 1179-1182
Author(s):  
Fan Bao Meng ◽  
Hong Mei Gao ◽  
Cui Zhi Zhu ◽  
Ri Li ◽  
Xiao Yan Lin
Keyword(s):  
Optical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Liquid Crystalline ◽  
Cholesteric Phase ◽  
Polymer Systems ◽  
Long Wavelength ◽  
Chemical Structures ◽  
Temperature Ranges ◽  
Synthesized Materials

A series of liquid crystalline (LC) oligomer films (IP-VP) were prepared by use of cyclo(tetramethylhydrogeno)siloxane (CTMHS), and two different cholesteric monomers that possess ortho- or para-substituted benzene. The chemical structures, liquid-crystalline properties and optical properties of the synthesized materials were characterized by various experimental techniques. All the samples showed cholesteric phase with very wide mesophase temperature ranges. From IP to VP, the glass transition temperature and the isotropic temperature decreased slightly with increase of C2PB component in the polymer systems. The maximum reflection bands shift to long wavelength from IP to VP, suggesting the helical pitch become longer with more ortho-substituted benzene in the polymer systems

Effect of Two Diferrent Mesogens on Liquid-Crystalline Properties of Chiral Side-Chain Liquid-Crystalline Polysiloxanes

2011 ◽  
Vol 415-417 ◽  
pp. 1395-1398
Author(s):  
Ji Wei Wang ◽  
Jun Qing Zi ◽  
Li Xian He ◽  
Guang Yong Chen ◽  
Yan Zhong Yang
Keyword(s):  
Liquid Crystalline ◽  
Proton Nuclear Magnetic Resonance ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Cholesteric Phase ◽  
Long Wavelength ◽  
Crystalline Polymers ◽  
Chemical Structures ◽  
Nuclear Magnetic Resonance Spectra ◽  
Temperature Ranges

Abstract. A series of liquid crystalline polysiloxanes were synthesized by cholesteric LC monomer and nematic LC monomer. The chemical structures and liquid-crystalline properties of the monomers and polymers were characterized by various experimental techniques including Fourier transform infrared (FTIR), proton nuclear magnetic resonance spectra (1H-NMR), differential scanning calorimetry (DSC), thermogravimetric analyses (TGA) , X-ray diffraction measurements (XRD) and polarizing optical microscopy (POM). All the liquid crystalline polymers showed liquid crystalline properties with wide mesophase temperature ranges. For the polymers bearing only of one nematic LC monomer, it showed nematic phase, while others showed cholesteric phase. With increase the content of nematic LC monomer in the polymers from P1 to P7, the glass transition temperature and the isotropic temperature increased on heating circles. Reflection spectra of cholesteric mesophase of the series of polymers showed that the reflected wavelength shifted to long wavelength with increase content of nematic LC monomer in the polymers in the polymer systems, suggesting that helical pitch (P) become long.

Synthesis and Characterization of Liquid Crystalline Polysiloxanes Containing Terminal Fluoromethyl Groups

2012 ◽  
Vol 466-467 ◽  
pp. 500-503
Author(s):  
Fan Bao Meng ◽  
Na Diao ◽  
Cui Zhi Zhu ◽  
Ri Li ◽  
Hong Mei Gao
Keyword(s):  
Nematic Phase ◽  
Liquid Crystalline ◽  
Synthesis And Characterization ◽  
Polymer Systems ◽  
Chemical Structures ◽  
Nematic Mesophase ◽  
Smectic Mesophase ◽  
Temperature Ranges ◽  
Synthesized Materials

A series of liquid crystalline (LC) polysiloxanes (PI-PV) were prepared by use of poly(methylhydrogeno)siloxane and two kinds of terminal olefinic monomers. The chemical structures and liquid-crystalline properties of the synthesized materials were characterized by various experimental techniques. From PI to PV, the glass transition temperature and the isotropic temperature decreased slightly with increase of terminal fluoromethyl units in the polymer systems. All the monomers and polymers showed nematic phase with wide mesophase temperature ranges. The polymers PI, PII and PIII displayed single nematic mesophase, but PIV and PV bearing more terminal fluoromethyl units showed another smectic mesophase besides nematic mesophase.

Preparation and Characterization of Chiral Cyclosiloxane-Based Liquid-Crystalline Elastomers Bearing Menthyl Groups

2012 ◽  
Vol 466-467 ◽  
pp. 445-448
Author(s):  
Qian Yue Li ◽  
Jun Xu ◽  
Wen Zheng Zhang ◽  
Peng Li
Keyword(s):  
Transition Temperature ◽  
Liquid Crystalline ◽  
Helical Structure ◽  
Visual Observation ◽  
Side Chain ◽  
Isotropic Phase ◽  
Long Wavelength ◽  
Chemical Structures ◽  
One Step

Chiral side-chain liquid-crystalline elastomers (LCEs) IP~IVP containig menthyl groups were synthesized by a one-step hydrosilylation reaction. The chemical structures and LC properties of the monomers and polymers were characterized by use of various experimental techniques. The effect of crosslinking mesogens on mesomorphic properties of the chiral LCEs was studied by swelling experiments. All the samples IP~IVP showed cholesteric mesophase when they were heated and cooled, proved by visual observation and X-ray measurements. The glass transition temperature (Tg) of elastomers increased slightly with increase of crosslinking mesogens in the polymer systems, but mesophase-isotropic phase transition temperature (Ti) decreased slightly, suggesting that the temperature range of mesophase became narrow with increase of crosslinking mesogens for all the elastomers. The maximum reflection bands shift slightly to long wavelength and become broad at the same temperature, indicating that the helical structure is partially disrupted because of both the constraint of chemical crosslinking agents and the different mesogenic units.

scholarly journals Studies on the Modification of Commercial Bisphenol-A-Based Epoxy Resin Using Different Multifunctional Epoxy Systems

2021 ◽  
Vol 2 (2) ◽  
pp. 419-430
Author(s):  
Ankur Bajpai ◽  
James R. Davidson ◽  
Colin Robert
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Bisphenol A ◽  
Epoxy Resin ◽  
Tensile Fracture ◽  
Chemical Structures ◽  
Amino Phenol ◽  
Epoxy Systems

The tensile fracture mechanics and thermo-mechanical properties of mixtures composed of two kinds of epoxy resins of different chemical structures and functional groups were studied. The base resin was a bi-functional epoxy resin based on diglycidyl ether of bisphenol-A (DGEBA) and the other resins were (a) distilled triglycidylether of meta-amino phenol (b) 1, 6–naphthalene di epoxy and (c) fluorene di epoxy. This research shows that a small number of multifunctional epoxy systems, both di- and tri-functional, can significantly increase tensile strength (14%) over neat DGEBA while having no negative impact on other mechanical properties including glass transition temperature and elastic modulus. In fact, when compared to unmodified DGEBA, the tri-functional epoxy shows a slight increase (5%) in glass transition temperature at 10 wt.% concentration. The enhanced crosslinking of DGEBA (90 wt.%)/distilled triglycidylether of meta-amino phenol (10 wt.%) blends may be the possible reason for the improved glass transition. Finally, the influence of strain rate, temperature and moisture were investigated for both the neat DGEBA and the best performing modified system. The neat DGEBA was steadily outperformed by its modified counterpart in every condition.

Structural and optical properties of lithium bismuthate glasses

2002 ◽  
Vol 17 (8) ◽  
pp. 1941-1944 ◽  
Author(s):  
A. Pan ◽  
A. Ghosh
Keyword(s):  
Optical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Structural Unit ◽  
Infrared Region ◽  
Compositional Variation ◽  
Optical Study ◽  
Structural And Optical Properties ◽  
Transmission Window ◽  
Ion Conducting

Structural and optical properties of ion - conducting lithium bismuthate glasses are reported here. The structure of these glasses has been explored from the compositional variation of the density, molar volume, and glass transition temperature. The optical study in the visible and infrared region indicates a large transmission window for these glasses. The BiO6 octahedra were identified as the main structural unit from the Raman spectra of these bismuthate glasses.

A comparative study of side chain liquid crystalline polymers and their monomers designed for nonlinear optical applications

1991 ◽  
Vol 6 (3) ◽  
pp. 604-609 ◽  
Author(s):  
R.B. Findlay ◽  
T.J. Lemmon ◽  
A.H. Windle
Keyword(s):  
Transition Temperature ◽  
Liquid Crystalline ◽  
Nonlinear Optical ◽  
Liquid Crystalline Polymers ◽  
Significant Degree ◽  
Side Chain ◽  
Crystalline Polymers ◽  
Chemical Structures ◽  
Optical Applications ◽  
Nonlinear Optical Applications

Characterizations of side chain liquid crystalline polymers and their monomers point toward chemical structures and processing techniques which optimize their suitability for nonlinear optical applications. Polymers with methacrylate backbones and nitrostilbene or nitrobiphenyl side groups are studied; they tend to form smectic phases, but no solid crystallinity. By copolymerizing with nonmesogenic backbone units, the smectic-isotropic transition temperature can be controlled and may fall below the glass transition temperature. There is evidence for a significant degree of pretransitional alignment due to the surface fields, and mesogen ordering perpendicular to flow-induced backbone alignment. Very rapid cooling can suppress the highly scattering polydomain smectic phase.

Chiral Liquid Crystal Polymers Containing Electron Donor- Acceptor Action-Synthesis and Characterization

2011 ◽  
Vol 284-286 ◽  
pp. 2284-2287
Author(s):  
Xiao Zhi He ◽  
Mei Tian ◽  
Yang Chen ◽  
Jing Zhao ◽  
Bao Yan Zhang
Keyword(s):  
Electron Donor ◽  
Liquid Crystalline ◽  
Proton Nuclear Magnetic Resonance ◽  
Liquid Crystal Polymers ◽  
Scanning Calorimetry ◽  
Cholesteric Phase ◽  
Chemical Structures ◽  
Heating And Cooling ◽  
Acceptor Group ◽  
Donor Acceptor

A series of new chiral side-chain liquid crystalline polymers with electron donor-acceptor action were prepared containing chiral monomer with donor group and nematic LC monomer with acceptor group. All polymers were synthesized by graft polymerization using polymethylhydro- siloxane as backbone. The mesomorphic properties were investigated by differential scanning calorimetry(DSC), polarizing optical microscopy(POM)，thermogravimetric analyses（TGA） and X-ray diffraction measurements(XRD). The chemical structures of monomers and polymers were confirmed by Fourier transform infrared (FTIR), proton nuclear magnetic resonance spectra(1H NMR and 13CNMR). M1 showed nematic phase and M2 turned out cholesteric phase on heating and cooling cycle. Polymers P3~P8 were cholesteric phase. Experimental results demonstrated that the glass transition temperatures and isotropization temperatures and the ranges of the mesophase temperature increased with increasing the content of chiral agent. All of the obtained polymers showed high thermal stability.

Preparation and characterization of post-derivatives from functional polystyrene (ATRP) with p-nitroanilineazomethine phenol and their thermal and optical study

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Xifei Yu ◽  
Guo Zhang ◽  
Tongfei Shi ◽  
P.K. Dutta ◽  
Lijia An
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Liquid Crystalline ◽  
Gel Permeation Chromatography ◽  
Side Chain ◽  
Scanning Calorimetry ◽  
Xrd Study ◽  
Covalently Linked

AbstractThe functional polystyrene, (Cl-PS)2-CHCOOCH2CH2OH (designated as XPSt and coded P2) was prepared by ATRP at 1300C using CuCl and bipyridine as catalysts, 2,2-dichloro acetate-ethylene glycol (DCAG) as multifunctional initiator and THF as solvent. 4-Nitoroaniline azomethine-4’ phenol (P1) as chromophores were covalently linked to the functional end groups of the polymer by using simple displacement reaction. The functional polystyrenes, namely XPSt (P2) and (PS)2-CHCOOCH2CH2OH, designated as X-PSt and coded P3 and their post-derivatives, namely, DXPSt (P4) and DX-PSt (P5) respectively were characterized by IR, NMR and UV spectroscopies, gel permeation chromatography (GPC) and thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), polarising optical microscopy (POM) and XRD studies. DSC showed that incorporation of chromophores in the side chains of polymers towards the polystyrene moiety increases the rigidity of the polymer and subsequently, its glass transition temperature; however the incorporation of side chain towards the alcoholic functional group decreases the glass transition temperature. The post derivatives do not play any significant role to increase the thermal stability (TGA). There was evidence for liquid crystalline properties in the resulting polymer derivative DXPSt (P4) as observed from POM study, which defines the alignment of chromophores into the polymers. The XRD study shows crystalline behaviour of the polymer derivative, P4. The polymer derivative, DXPSt (P5) does not show such behaviour and this may be due to the bonding of azomethine towards the short chain alcoholic telechelic alcoholic sides of the copolymer.

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