Shape Amphiphiles:  Mixing Rods and Disks in Liquid Crystals

Date, Richard W.; Bruce, Duncan W.

doi:10.1021/ja0357947

Cited by 117 publications

(95 citation statements)

References 10 publications

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“…In addition, unusual nanostructured colloidal particles have also been observed from compounds in libraries 2 and 4 by slow addition of a selective solvent, e.g., water, into their solution in 1,4-dioxane. A large difference exists between the colloidal particles obtained from a pair of topological isomers, AC 60 -PS 44 and AC 60 -2PS 23 . Dynamic light scattering (DLS) shows a unimodal narrow size distribution for the formed particles with sizes centered at 220 nm for AC 60 -PS 44 and 140 nm for AC 60 -2PS 23 , respectively (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Specific recognition and binding events, such as DNA hybridization and protein folding, are based on collective and cooperative multiple secondary interactions. More recently, anisotropy in shape has also been recognized as a critical factor in the self-assembly process due to packing constraints (17)(18)(19)(20)(21)(22), as indicated by the emerging concept of "shape amphiphiles" (23,24). However, it remains challenging to design nanomaterials "from scratch" (25) that can generate diverse structures at a specific length scale, e.g., the nanostructures with feature sizes around 10 nm or smaller.…”

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confidence: 99%

See 1 more Smart Citation

Giant surfactants provide a versatile platform for sub-10-nm nanostructure engineering

Yue

Hsieh

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

205

163

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The engineering of structures across different length scales is central to the design of novel materials with controlled macroscopic properties. Herein, we introduce a unique class of self-assembling materials, which are built upon shape-and volume-persistent molecular nanoparticles and other structural motifs, such as polymers, and can be viewed as a size-amplified version of the corresponding small-molecule counterparts. Among them, "giant surfactants" with precise molecular structures have been synthesized by "clicking" compact and polar molecular nanoparticles to flexible polymer tails of various composition and architecture at specific sites. Capturing the structural features of small-molecule surfactants but possessing much larger sizes, giant surfactants bridge the gap between small-molecule surfactants and block copolymers and demonstrate a duality of both materials in terms of their self-assembly behaviors. The controlled structural variations of these giant surfactants through precision synthesis further reveal that their selfassemblies are remarkably sensitive to primary chemical structures, leading to highly diverse, thermodynamically stable nanostructures with feature sizes around 10 nm or smaller in the bulk, thin-film, and solution states, as dictated by the collective physical interactions and geometric constraints. The results suggest that this class of materials provides a versatile platform for engineering nanostructures with sub-10-nm feature sizes. These findings are not only scientifically intriguing in understanding the chemical and physical principles of the self-assembly, but also technologically relevant, such as in nanopatterning technology and microelectronics. giant molecules | shape amphiphiles | hybrid materials | microphase separation | colloidal particles P hysical properties of materials are dictated by the hierarchical arrangements of atoms, molecules, and supramolecular assemblies across different length scales. The construction and engineering of structures at each length scale, especially at the 2-to 100-nm scale (1), are critically important in achieving desired macroscopic properties. As the traditional top-down lithography techniques face serious challenges in fabricating 2D and 3D nanostructured materials with sub-20-nm feature sizes (2), the bottom-up approach based on self-organization or directed assembly of functional molecules provides a promising alternative. The past decades have witnessed the development of diverse self-assembly building blocks ranging from small-molecule surfactants (3), block copolymers (4), and dendrimers (5) to DNAs (6, 7), peptides (8), and proteins (9). Notably, these motifs have enabled the programmed self-assembly of nanomaterials as demonstrated in DNA-coated nanoparticles (10-13). These studies have greatly improved our understanding of the thermodynamics and kinetics of self-assembly processes and opened enormous possibilities in modern nanotechnology.Noncovalent interactions, such as hydrogen bonding, amphiphilic effect, π-π interacti...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Giant surfactants provide a versatile platform for sub-10-nm nanostructure engineering

Yue

Hsieh

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

205

163

View full text Add to dashboard Cite

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“…Besides using specific rod-disc interactions, another strategy for overcoming phase separation in mixtures may be that of using molecules with both rod-and disc-like mesogenic units joined by a flexible alkyl spacer (the so-called shape amphiphiles [161]). After the work of Fletcher and Luckhurst [162], other molecular design concepts have been explored [162,163,161,164,165,166] obtaining N u but not N b .…”

Section: Mixturesmentioning

confidence: 99%

“…After the work of Fletcher and Luckhurst [162], other molecular design concepts have been explored [162,163,161,164,165,166] obtaining N u but not N b . So far, the mesogen with closest resemblance to the theoretical cartoon of joined mesogens is the one of Kouwer and Mehl [164].…”

Section: Mixturesmentioning

confidence: 99%

Computer Simulations of Biaxial Nematics

Berardi¹,

Zannoni²

2015

Biaxial Nematic Liquid Crystals

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“…Experimentally the biaxial phase was first obtained in a lyotropic, ternary mixture of potassium laurate, 1-Decanol and D 2 O in 1980 [24] and more recently in bent-core compounds [25,26], organo-siloxane tetrapodes [27,28], LC polymers [29] and colloidal systems of Goethite particles [30]. Though recent experiments [31,32] point to low transition enthalpies for rod-disc systems, an unambiguous biaxial phase has not been established in such systems. From the point of view of application, it is anticipated that the minor director could switch more readily compared to the major director in an external field [33,34] leading to faster response times.…”

Section: Introductionmentioning

confidence: 99%

Reexamination of the mean-field phase diagram of biaxial nematic liquid crystals: Insights from Monte Carlo studies

et al. 2015

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Investigations of the phase diagram of biaxial liquid crystal systems through analyses of general Hamiltonian models within the simplifications of mean-field theory (MFT), as well as by computer simulations based on microscopic models, are directed towards an appreciation of the role of the underlying molecular-level interactions to facilitate its spontaneous condensation into a nematic phase with biaxial symmetry. Continuing experimental challenges in realising such a system unambiguously, despite encouraging predictions from MFT for example, are requiring more versatile simulational methodologies capable of providing insights into possible hindering barriers within the system, typically gleaned through its free energy dependences on relevant observables as the system is driven through the transitions. The recent brief report from this group [B. Kamala Latha, et. al., Phys. Rev. E 89, 050501(R), 2014], summarising the outcome of detailed Monte Carlo simulations carried out employing entropic sampling technique, suggested a qualitative modification of the MFT phase diagram as the Hamiltonian is asymptotically driven towards the so-called partlyrepulsive regions. It was argued that the degree of the (cross) coupling between the uniaxial and biaxial tensor components of neighbouring molecules plays a crucial role in facilitating, or otherwise, a ready condensation of the biaxial phase, suggesting that this could be a plausible factor in explaining the experimental difficulties. In this paper, we elaborate this point further, providing additional evidences from curious variations of free-energy profiles with respect to the relevant orientational order parameters, at different temperatures bracketing the phase transitions. 1 arXiv:1509.03834v1 [cond-mat.soft]

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Shape Amphiphiles: Mixing Rods and Disks in Liquid Crystals

Cited by 117 publications

References 10 publications

Giant surfactants provide a versatile platform for sub-10-nm nanostructure engineering

Giant surfactants provide a versatile platform for sub-10-nm nanostructure engineering

Computer Simulations of Biaxial Nematics

Reexamination of the mean-field phase diagram of biaxial nematic liquid crystals: Insights from Monte Carlo studies

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