Phase behavior and elastic properties of a slightly crosslinked liquid crystalline main-chain polymer

Hanus, K. -H.; Pechhold, W.; Soergel, Fritz; Stoll, B.; Zentel, Rudolf

doi:10.1007/bf01490246

Cited by 38 publications

(27 citation statements)

References 16 publications

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“…For monodomains of these systems large strain thermal actuation has been demonstrated, drastically exceeding the effects found for side chain elastomers. Up to now, different synthetic routes to MC-LCEs have been proposed, including either polyaddition reactions (hydrosilylation, epoxyresins) for the in situ formation of the network [7][8][9][10] or the use of thermoplastic, selforganizing triblock copolymers. [11,12] By applying uniaxial stress during the formation of the network, monodomains of the elastomers could be prepared.…”

Section: Introductionmentioning

confidence: 99%

Monodomain Liquid Crystal Main Chain Elastomers by Photocrosslinking

Beyer¹,

Terentjev²,

Zentel³

2007

Macromol. Rapid Commun.

100

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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: Introductionmentioning

confidence: 99%

Monodomain Liquid Crystal Main Chain Elastomers by Photocrosslinking

Beyer¹,

Terentjev²,

Zentel³

2007

Macromol. Rapid Commun.

100

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“…Figure 11 shows the dynamic mechanical behavior as function of frequency for network #3 with the PDES block in the melt and in the mesophase, respectively. In the latter case, the samples shows behavior similar to slightly crosslinked amorphous polymers in the rubbery state, with the real part of the compliance (J 9) being nearly independent of the frequency at a level of the order of 10 -6 Pa -1 [11]. The temperature dependence of the compliance (Fig.…”

Section: Mechanical Behaviormentioning

confidence: 88%

“…Dynamic mechanical measurements were performed on a home-built dynamic mechanical spectrometer, operating at frequencies between 10 -4 and 100 Hz [11].…”

Section: Methodsmentioning

confidence: 99%

Block copolymers and networks from polybutadiene and polydiethylsiloxane

Molenberg¹,

Möller²,

Soden³

1998

Acta Polym.

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Di‐, tri‐, and star block copolymers from polybutadiene (PB) and polydiethylsiloxane (PDES) have been synthesized by sequential anionic polymerization, using mono‐, di‐, and tetrafunctional terminating agents. The tri‐ and star block copolymers were crosslinked by hydrosilylation of the PB double bonds with chlorodimethylsilane, followed by condensation of the chlorosilane groups with ambient humidity. The thus obtained rubbers showed elastomeric tensile behavior and stressinduced mesophase formation. Both the block copolymers and the rubbers showed microphase separation into PB and PDES domains.

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“…For these systems synthetic procedures described this far mainly involve the in situ formation of the network by either polyaddition reactions (hydrosilylation, epoxy resins) [16][17][18][19] or the use of thermoplastic, self-organizing triblock-copolymers, [20,21] making these systems unsuitable for the sample geometries known for SC-LCEs.…”

Section: Full Papermentioning

confidence: 99%

(Photo)crosslinkable Smectic LC Main‐Chain Polymers

Beyer

Braun

Zentel

2007

Macro Chemistry & Physics

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This paper presents the synthetic route to SmA LC main‐chain polymers, that can be (photo)crosslinked without solvent in the bulk phase. They are based on soluble polymalonates, in which higher ordered phases can be suppressed by copolymerization with a laterally brominated biphenyl. Two routes were developed to incorporate the crosslinkable groups into the polyester backbone. The first consists in the incorporation of phenols into the polyester. These phenols are not reactive enough to participate in the transesterification reaction used to build up the polymer, but they can be esterified afterwards with acrylates. Thermally or photochemically created radicals then start the crosslinking. The second route is based on the incorporation of benzophenone as side group. It allows a photochemical crosslinking. Crosslinked fibers (monodomains) show the potential of the smectic LC main‐chain elastomers as actuators.magnified image

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Phase behavior and elastic properties of a slightly crosslinked liquid crystalline main-chain polymer

Cited by 38 publications

References 16 publications

Monodomain Liquid Crystal Main Chain Elastomers by Photocrosslinking

Monodomain Liquid Crystal Main Chain Elastomers by Photocrosslinking

Block copolymers and networks from polybutadiene and polydiethylsiloxane

(Photo)crosslinkable Smectic LC Main‐Chain Polymers

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