Synthesis and curing of novel LC twin epoxy monomers for liquid crystal thermosets

Shiota, Atsushi; Ober, Christopher K.

doi:10.1002/(sici)1099-0518(199605)34:7<1291::aid-pola16>3.0.co;2-4

Cited by 86 publications

(54 citation statements)

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“…[17,28] Various authors have observed that the introduction of a flexible spacer that decouples the reactive end-functional group from the rigid-rod mesogenic group can also lower the melting temperature and increase the mesophase stability of LCER in most cases. [4,5,23,25,[29][30][31][32][33][34][35][36][37] Galià and co-workers have synthesized phenylhydroquinine bis-6-[6-(glycidyloxy)hexyloxy]-2-naphthoate (Gly A) from 6-hydroxy-2-naphthoic acid. A nematic mesophase was observed between 109 and 123 8C on heating and between 123 8C and room temperature on cooling.…”

Section: Introductioncontrasting

confidence: 99%

Novel Triaromatic Ester Mesogenic Liquid Crystalline Epoxy Resin Containing Both Methyl Substituent and Ethoxy Flexible Spacer: Synthesis and Curing

Liu¹,

Zhou²,

Zhao³

et al. 2008

Macro Chemistry & Physics

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A novel triaromatic ester liquid crystalline epoxy resin (LCER) that contains both a methyl substituent and an ethoxy flexible spacer, p‐methylphenylene di{4‐[(2,3‐epoxypropoxy)ethoxy]benzoate} (MPEPEB), has been synthesized. The mesotropic property has been investigated by differential scanning calorimetry (DSC) and polarized light optical microscopy (POM). MPEPEB shows a lower melting temperature at 78.7 °C and a broad nematic mesophase temperature range of about 55 °C. Meanwhile MPEPEB shows a mesophase to −50 °C upon cooling. The curing behavior of MPEPEB with 2,6‐diamino‐3,5‐diethyltoluene (DAE) has been investigated by means of DSC and POM during isothermal and dynamic processes. Although there is little difference between the activation energies obtained from the kinetic data, a marked difference is found between the isothermal and dynamic investigation. The curing reaction in the isothermal investigation roughly obeys n‐th order kinetics, while two exothermal peaks appear in the dynamic DSC curves of MPEPEB/DAE. A comparison of the isothermal and dynamic data shows that the curing rate is not a unique function of temperature and curing degree. The cured networks have lower glass temperatures and show a mesophase at room temperature which disappears at about 86–88 °C.magnified image

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Section: Introductioncontrasting

confidence: 99%

Novel Triaromatic Ester Mesogenic Liquid Crystalline Epoxy Resin Containing Both Methyl Substituent and Ethoxy Flexible Spacer: Synthesis and Curing

Liu¹,

Zhou²,

Zhao³

et al. 2008

Macro Chemistry & Physics

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“…Our results obtained from dimeric azomethine monomers are different from those of Shiota and Ober, [16] in that the compounds described here are able to lock smectic networks. This may be due to the structure of the mesogen, which in our case is polarized and therefore cannot stabilize an ordered smectic organization in which the charges of the same sign are located closely to each other.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Crosslinking of a Series of Dimeric Liquid Crystalline Epoxy Resins Containing Imine Mesogens

Ribera

Mantecón

Serra

2001

Macromol. Chem. Phys.

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Eight aromatic imine liquid crystalline (LC) diepoxides with dimeric architecture from readily available commercial reagents were synthesized and characterized by spectroscopic techniques. We characterized their liquid crystalline mesophases by differential scanning calorimetry (DSC), hot‐stage polarized‐light optical microscopy (POM) and wide‐angle X‐ray diffraction (WAXS). The mesomorphism of the products was related to their structure, which varies in the length of the central spacer. Odd‐membered spacer mesogens lead to the formation of smectic C mesophases, whereas even‐membered samples of this series lead to the formation of smectic A and/or nematic mesophases. By relating the calculated molecular parameters to the layer spacings obtained by WAXS, we deduced the organization of the mesogens in the smectic phases, since the dimeric compounds present a variety of possible arrangements. Liquid crystal thermosets (LCTs) were obtained from these monomers by isothermal curing with equimolar amounts of 2,4‐diaminotoluene (DAT). The curing process was studied by calorimetry and their thermal stability was evaluated by thermogravimetry (TGA). Most monomers produced nematic‐like networks, but in one case a smectic C mesophase was also locked.

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“…The third diamine (SAA) has, two different amine functions of unequal reactivity and seems to favor formation of a smectic phase as described by some researchers. [12] MDA reacts with the epoxy monomer at the lowest temperature of the three diamines. The epoxy compound reacts with DABP more slowly than with MDA, while the reaction between epoxy and SAA occurs quite gradually.…”

Section: Cure and Phase Changementioning

confidence: 99%

Curing Reaction and Phase Change in a Liquid Crystalline Monomer

Shim

Kim³

2001

Macromol. Chem. Phys.

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Synthesis and curing of novel LC twin epoxy monomers for liquid crystal thermosets

Cited by 86 publications

References 1 publication

Novel Triaromatic Ester Mesogenic Liquid Crystalline Epoxy Resin Containing Both Methyl Substituent and Ethoxy Flexible Spacer: Synthesis and Curing

Novel Triaromatic Ester Mesogenic Liquid Crystalline Epoxy Resin Containing Both Methyl Substituent and Ethoxy Flexible Spacer: Synthesis and Curing

Synthesis and Crosslinking of a Series of Dimeric Liquid Crystalline Epoxy Resins Containing Imine Mesogens

Curing Reaction and Phase Change in a Liquid Crystalline Monomer

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