Entropy‐Driven Helical Mesostructure Formation with Achiral Cationic Surfactant Templates

Han, Yu; Zhao, Lan; Ying, Jackie Y.

doi:10.1002/adma.200602703

Cited by 123 publications

(128 citation statements)

References 20 publications

(27 reference statements)

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“…2 are very similar to the TEM textures of rods formed by mesoporous silica with helical twist [23][24][25][26] . An interesting feature of both systems is that the families of parallel fringes can be bent.…”

Section: Resultssupporting

confidence: 65%

Helical nanofilaments of bent-core liquid crystals with a second twist

et al. 2014

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The B4 phase of bent-core liquid crystals has been shown to be an assembly of twisted layers stacked to form helical nanofilaments. Interestingly, some of them have structural colours that cannot be explained by the nanofilaments alone. Here cryogenic-transmission electron microscopy observations on 40-120 nm films of four bent-core liquid crystal materials show that the filaments are present even in contact with a carbon substrate with only minor deformation, thus representing bulk properties. We find that the subsequent arrays of nanofilaments are not parallel to each other, but rotate by an angle of 35-40°with respect to each other. This doubly twisted structure can explain the structural colour. Being principally different from the packing of molecules in the twist grain boundary and blue phases, the double-twist structure of helical nanofilaments expands the rich word of nanostructured organic materials.

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Section: Resultssupporting

confidence: 65%

Helical nanofilaments of bent-core liquid crystals with a second twist

et al. 2014

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“…[9,10,13,15] Importantly, the relationship between the well-studied straight internal helical structure and the complicated HH mesostructures has not been reported until now. On one hand, there have been few methods to simply synthesize a series of helical mesostructures with different helical parameters.…”

Section: Introductionmentioning

confidence: 94%

Evolution of Helical Mesostructures

Yuan

Zhao

Liu

et al. 2010

Chemistry A European J

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An intriguing evolution from a simple internal helix to a hierarchical helical (HH) mesostructure with both internal and external helices or a complicated screwlike and concentric circular (CC) mesostructure is successfully observed. The complicated helical structures are determined by TEM studies and 3D electron tomography. We demonstrate a topological helix-coil transition between the internal and external helices to reveal the origin of the HH mesostructure and the relationship between the straight helical and HH rods. Moreover, the boundary condition of the helix-coil transition is clarified to explain in detail the formation of complex helical structures, such as the screwlike mesostructure. It is proposed that the final structural characteristics are determined exactly by the balance between the decrease in the surface free energy and the maintenance of the hexagonal packing in one individual rod, which explains the formation of unusual CC, HH, and screwlike morphologies in one pot. Our success has opened new opportunities in the characterization of complex porous architectures, thus paving a way to remarkable advances in the fields of synthesis, understanding, and application of novel porous materials.

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“…Recently, significant research interest has been held in the formation of helical mesostructures with chiral channels [16][17][18][19] and concentric circular (CC) mesostructures, [20][21][22][23][24] as a result of their unique morphologies and internal pore architectures. Helical and CC mesostructured materials with pure silica composition have been successfully synthesized through acid-or basic-catalyzed sol-gel processes by using chiral or achiral surfactants as templates and tetraethyl orthosilicate (TEOS) or sodium silicate [25] as silica sources.…”

Section: Introductionmentioning

confidence: 99%

Periodic Mesoporous Organosilicas with Helical and Concentric Circular Pore Architectures

Yuan

Zhao

Liu

et al. 2009

Chemistry A European J

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This study systematically investigates periodic mesoporous organosilicas (PMOs) with controlled helical and concentric circular (CC) pore architectures prepared through a basic-catalyzed sol-gel process by using an achiral cationic surfactant trimethyloctadecylammonium bromide (C(18)TAB) as a structure-directing agent, perfluorooctanoic acid (PFOA) as an additive, and 1,2-bis(triethoxysilyl)ethane (BTEE) as a hybrid silica precursor. By increasing the weight ratio of PFOA/C(18)TAB, a pore architecture transition of PMO materials from hexagonal-arrayed, straight longitudinal channels to helical and CC mesostructures is achieved; such a transition has not been observed before in PMO materials. Our discovery is helpful in understanding the supramolecular cooperative assembly of hybrid materials and their structural and morphological evolution, which are important in the future applications of PMO materials.

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Entropy‐Driven Helical Mesostructure Formation with Achiral Cationic Surfactant Templates

Cited by 123 publications

References 20 publications

Helical nanofilaments of bent-core liquid crystals with a second twist

Helical nanofilaments of bent-core liquid crystals with a second twist

Evolution of Helical Mesostructures

Periodic Mesoporous Organosilicas with Helical and Concentric Circular Pore Architectures

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