Liquid‐Crystalline Colloidal Particles

We have developed a method to convert 10 different LC acrylate monomers into colloids by dispersion polymerization. This yields nine different types of anisotropic colloids with nematic and different smectic phases. The diameter of these colloids mostly varied between 0.5 and 3.5 µm; it can be adjusted by variation of the solvent mixture and it can be systematically increased by seed polymerization. The polydispersity of the anisotropic colloids is thereby often below 10%. Polarizing microscopy shows that colloids of a size between about 2 to 4 µm appear to have a bipolar director configuration. Smaller colloids appear uniaxially oriented, the resolution does, however, not allow a more refined investigation of the director pattern. These anisotropic spheres (diameter between 0.7 and 3.7 µm) can be trapped with an optical tweezers. Circularly polarized light transfers a torque to the particles, enabling one to rotate them clockwise and anticlockwise, which makes these spheres attractive as actuators. The size dependence of their rotational frequency makes it additionally possible to determine changes of the director configuration with size. For a nematic colloid (P 6), it could be shown that the anisotropy stays constant from 1.6 to 3.4 µm.

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“…Monomer M 12 was synthesized in analogy to monomer M 11. 13 Yield: 72% of a colorless solid, mp 74°C.…”

Section: -[2-(2-mentioning

confidence: 99%

“…13 These colloids have diameters of a few micrometers and can therefore be used for experiments with optical tweezers, of which we show some examples.…”

Section: Introductionmentioning

confidence: 97%

Anisotropic Particles from LC Polymers for Optical Manipulation

et al. 2006

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“…[12][13][14] This uniform orientation could be used to rotate them by an optical tweezer with polarized light. [14] In addition, a uniform director orientation was found in some LC colloids prepared by the miniemulsion process (up to 100 nm).…”

Section: Introductionmentioning

confidence: 99%

Nanosized Shape‐Changing Colloids from Liquid Crystalline Elastomers

Haseloh

Ohm

Smallwood

et al. 2010

Macromol. Rapid Commun.

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A method to prepare shape-changing nanospheres from liquid crystalline elastomers is reported. The nanosized colloids are prepared by a miniemulsion process. During this process, colloids are prepared from a liquid crystalline (LC) main-chain polyester and subsequently crosslinked into a nanometer-sized LC elastomer. The ability of these LC elastomers to change their shape at the phase transition temperature from the smectic A to the isotropic phase was detected by temperature-dependent transmission electron microscopy. The phase transition-induced shape change leads to strongly shape anisotropic nanosized elastomer particles.

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“…[18] LC colloidal particles possessing switching properties were prepared through emulsion polymerization. [19] However, these methods have limits and require of the article's abstract page, which can be accessed from the journal's homepage at http://www.mrc-journal.de, or from the author.…”

Section: Introductionmentioning

confidence: 99%

Easy Fabrication and Morphology Control of Supramolecular Liquid‐Crystalline Polymer Microparticles

Liu

Kobayashi

2010

Macromol. Rapid Commun.

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A novel kind of supramolecular liquid-crystalline polymer (SLCP) microparticles was successfully fabricated with an azopyridyl polymer and sebacic acid by combining a simple self-organized precipitation method with hydrogen bonding interactions. Upon slow evaporation of a mixed solution of a volatile good solvent and a nonvolatile poor one, walnutlike microparticles showing wrinkled surfaces and LC natures were obtained. The diacid might play a crucial role in the formation of SLCP particles. Without addition of the diacid, neither wrinkled surfaces nor LC natures were observed in azopyridyl polymer microparticles. The fabricated SLCP microparticle possessed not only photoresponsive properties (due to azopyridyl groups) but also LC ordering, which might enable them to find advanced applications.

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Liquid‐Crystalline Colloidal Particles

Cited by 39 publications

References 16 publications

Anisotropic Particles from LC Polymers for Optical Manipulation

Anisotropic Particles from LC Polymers for Optical Manipulation

Nanosized Shape‐Changing Colloids from Liquid Crystalline Elastomers

Easy Fabrication and Morphology Control of Supramolecular Liquid‐Crystalline Polymer Microparticles

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