Photoswitchable Smectic Liquid‐Crystalline Elastomers

Beyer, Patrick; Zentel, Rudolf

doi:10.1002/marc.200500093

Cited by 38 publications

(24 citation statements)

References 24 publications

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“…[19] The synthesis of the monomers and the crosslinkable LC polyester is described elsewhere. [20] In order to suppress crystallinity, 50 mol-% of the mesogenic biphenyl groups were laterally substituted with bromine. As a photocrosslinker, 15 mol-% of a malonate comonomer containing a photoreactive benzophenone group were used.…”

Section: Experimental Part Synthesis and Characterization Of The Linementioning

confidence: 99%

Monodomain Liquid Crystal Main Chain Elastomers by Photocrosslinking

Beyer¹,

Terentjev²,

Zentel³

2007

Macromol. Rapid Commun.

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101

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A new synthetic strategy for the preparation of macroscopically oriented smectic main chain liquid crystal elastomers (MC‐LCE) by the photocrosslinking of laterally functionalized polyesters is presented. X‐ray measurements proved the formation of the monodomain and allowed a quantitative determination of the order parameter. The thermo‐actuation of our material at the phase transition from the liquid‐crystalline to the isotropic phase was demonstrated by temperature dependent measurements of the sample length, showing a fully reversible shape change of ≈40%. Mechanical measurements showed that the sample can be stretched by up to 60% along the smectic layer normal without any reorientation of the structure, in contrast to earlier experiments and theoretical predictions. The results are discussed in the context of limited smectic layer correlation in different types of smectic materials.magnified image

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Section: Experimental Part Synthesis and Characterization Of The Linementioning

confidence: 99%

Monodomain Liquid Crystal Main Chain Elastomers by Photocrosslinking

Beyer¹,

Terentjev²,

Zentel³

2007

Macromol. Rapid Commun.

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101

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“…The mesogenic molecules tend to recover their alignment along the director direction to restore their positive contribution to the nematic potential of the mesophase. [27][28] The analysis of nematic solutions in ZLI-1695 with different contents of AZO2 NO 2 demonstrated that the rate of the thermal process is independent of the chromophore concentration thereby following a first-order profile (Table 1, entries 9, 10, 12 and 13).…”

Section: Resultsmentioning

confidence: 99%

Increasing the Isomerisation Kinetics of Azo Dyes by Chemical Bonding to Liquid‐Crystalline Polymers

García-Amorós

Finkelmann

Velasco

2011

Chemistry A European J

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It is well known that the proper substitution of the azobenzene core allows tuning the thermal cis-to-trans isomerisation kinetics of azo dyes. The thermal isomerisation process of nitro-substituted azobenzenes is accelerated up to 13 times with respect to that in the common isotropic solvents when they are doped in nematic low molar mass liquid crystals. This kinetic acceleration is even stronger when these azo dyes are covalently linked to a nematic siloxane polymer. In this environment, the isomerisation process is accelerated more than 10(3) times. This effect is presented herein for the first time. The possible application of the networks obtained as possible photo-actuators has been also considered.

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“…Its synthesis and characterization have been described elsewhere. [10] The polymer forms broad smectic phases (S A , S C *, and an unknown smectic phase S X ). The ferroelectric transition from S A to S C * is observed at T C = 66°C.…”

Section: Resultsmentioning

confidence: 99%

“…The synthesis and characterization of the investigated polymer has been described in detail in the literature [10].…”

Section: Methodsmentioning

confidence: 99%

“…1). [10] For the investigation of photoinduced effects, ferroelectric LC polymers are of special interest due to the spontaneous electric polarization P S exhibited by the chiral smectic C phase (S C *). As P S vanishes at the phase transition to the smectic A (S A ) phase (Curie temperature, T C ), its measurement enables us to accurately monitor photoinduced phase shifts.…”

Section: Introductionmentioning

confidence: 99%

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Photoresponsive Ferroelectric Liquid‐Crystalline Polymers

Beyer

Krueger

Gießelmann

et al. 2006

Adv Funct Materials

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The photoresponse of ferroelectric smectic side‐chain liquid‐crystalline (LC) polymers containing a photoisomerizable azobenzene derivative as a covalently linked photochromic side group is investigated. By static measurements in different photostationary states, the effect of trans–cis isomerization on the material's phase‐transition temperatures and its ferroelectric properties (spontaneous electric polarization PS and director tilt angle θ) are analyzed. It turns out that the Curie temperature (transition SC* to SA) can be reversibly shifted by up to 17 °C. The molecular mechanism of this “photoferroelectric effect” is studied in detail using time‐resolved measurements of the dye's optical absorbance, the director tilt angle, and the spontaneous polarization, which show a direct response of the ferroelectric parameters to the molecular isomerization. The kinetics of the thermal reisomerization of the azo dye in the LC matrix are evaluated. A comparison to the reisomerization reaction in isotropic solution (toluene) reveals a faster thermal relaxation of the dye in the LC phase.

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Photoswitchable Smectic Liquid‐Crystalline Elastomers

Cited by 38 publications

References 24 publications

Monodomain Liquid Crystal Main Chain Elastomers by Photocrosslinking

Monodomain Liquid Crystal Main Chain Elastomers by Photocrosslinking

Increasing the Isomerisation Kinetics of Azo Dyes by Chemical Bonding to Liquid‐Crystalline Polymers

Photoresponsive Ferroelectric Liquid‐Crystalline Polymers

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