Ionic Thermotropic Liquid Crystal Dendrimers

Martín‐Rapún, Rafael; Marcos, Mercedes; Omenat, Ana; Barberá, Joaquín; Romero, Pilar; Serrano, José Luís

doi:10.1021/ja042264h

Cited by 103 publications

(119 citation statements)

References 42 publications

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“…We employ a numerical solution of the SCFT equations (eq [13][14][15][16][17][18][19] to evaluate the canonical ensemble free energies for various candidate inhomogeneous phases in their unit cells. Initial field configurations are seeded in order to produce a unit cell of a given mesophase, and the modified diffusion equation (eq 9) is solved pseudospectrally with an operator splitting scheme.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…38 Using the calculated propagators, the volume fractions and single-molecule partition functions are evaluated. The W A , W B , W C , and P fields are subsequently relaxed using various convergence schemes 26,39,40 in order to satisfy the remaining SCFT equations, (eqs [16][17][18][19]. We also minimize the free energy density with respect to the volume and shape of the periodic simulation box with a variable cell shape method.…”

Section: Summary and Discussionmentioning

confidence: 99%

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Novel Phase Morphologies in a Microphase-Separated Dendritic Polymer Melt

Lee¹,

Elliott²,

Mezzenga³

et al. 2009

Macromolecules

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Equilibrium phase morphologies of two different dendritic block copolymer melts are calculated and compared. These copolymers have a pitchfork-like architecture and consist of three distinct blocks that correspond roughly to the handle, the connecting middle dendron structure, and the attached tines of a pitchfork. The first melt considered consists of a copolymer that has a simple Y-junction middle block, and it connects the handle to two tines. The second is similar except its dendritic middle block branches twice to connect to four tines. Polymeric segments are modeled as flexible Gaussian threads and interactions between dissimilar blocks are all contact-like, Flory-Huggins repulsions. All calculations are done for incompressible melts in the context of self-consistent mean-field theory. We find that several morphologies compete for stability depending on the architecture and lengths of the blocks as well as their incompatibilities. As many as four stable two-dimensional phases appear in the phase diagram including: columnar square, rectangular and hexagonally packed structures. A long handle and a moderate length of the dendron are essential for stabilizing the square phases, and the four tine copolymer shows a larger region of stability for these phases compared to the Y-junction middle block system. A remarkable continuous phase transition between the square and rectangular phases is also found and investigated.

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Section: Summary and Discussionmentioning

confidence: 99%

Section: Summary and Discussionmentioning

confidence: 99%

Novel Phase Morphologies in a Microphase-Separated Dendritic Polymer Melt

Lee¹,

Elliott²,

Mezzenga³

et al. 2009

Macromolecules

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“…26 In the case of ionic complexation, various polyelectrolyte architectures such as linear and hyperbranched polymers as well as dendrimers have been explored as macromolecular templates and complexed with ionic mesogenes such as hydrocarbon-based surfactants and rigid rods. [27][28][29][30] Biopolyelectrolytic systems have also been studied as comblike polymers templates for complexation with ionic mesogenes in investigations relevant to pH-responsive systems and artificial biomembranes. 31 Recently, we have reported the use of cationic dendronized polymers as a model system to design comblike liquid-crystalline polymers where microphase-segregated structures can be tailored by both the mesogen type and length as well as the generation of the dendronized polymer.…”

Section: Introductionmentioning

confidence: 99%

Comblike Liquid-Crystalline Polymers from Ionic Complexation of Dendronized Polymers and Lipids

et al. 2007

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This work describes the self-assembly behavior, the structure, the state, and phase diagrams of comblike liquid-crystalline polymers obtained by supramolecular ionic complexation of cationic dendronized polymers (PG1-PG3) and anionic sulfonated lipid surfactants. In order to characterize the influence of both the polymer and the surfactant on the microphase separation of these complexes, dendronized polymers with generation 1 e n e 3, carrying 2 n positive charges per monomer, were complexed with a stoichiometric amount of anionic sodium alkyl monosulfate surfactants with hydrocarbon chain of C 8 , C 12 , C 14 , and C 18 lengths. Supramolecular complexes were obtained in water, and the complexation process was monitored by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance. After drying and thermal annealing under high vacuum, the complexes showed thermotropic liquid-crystalline behavior as demonstrated by both cross-polarized optical microscopy and differential scanning calorimetry. Small-angle X-ray scattering allowed determining the respective lattice parameters and type of structures for all the complexes considered. Depending on both generation and lipid chain length, amorphous isotropic fluid, columnar rectangular, columnar hexagonal, columnar tetragonal, and lamellar phases were observed, each characterized by a specific order-disorder transition temperature (T ODT ).

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“…More recently, other types of macromolecular polyelectrolytes have been explored such as dendrimers [11,12] and dendronized polymers, [13,14] leading to richer polymorphism compared to previous systems. In particular it has been shown that for these classes of highly branched systems can form columnar phases of various lattices such as rectangular hexagonal and lamellar types.…”

Section: Introductionmentioning

confidence: 99%

Functional Columnar Liquid Crystalline Phases From Ionic Complexes of Dendronized Polymers and Sulfate Alkyl Tails

Canilho¹,

Kasëmi

Schlüter

et al. 2008

Macromolecular Symposia

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Summary:We describe how cationic dendronized polymers of generations 1, and 2 and anionic monoalkyl tails can be combined by supramolecular ionic complexation into comb-like liquid crystalline polymers. The final structures in bulk of these supramolecular complexes were studied by differential scanning calorimetry (DSC), cross-polarized optical microscopy (CPOM), small angle x-rays scattering (SAXS) and transmission electron microscopy (TEM). The combination of these techniques allowed elucidating (i) that these complexes exhibit thermotropic behaviour, (ii) that various liquid crystalline structures in the 3-5 nm length scale can be obtained such as columnar rectangular, columnar tetragonal, columnar hexagonal and lamellar, depending both on alkyl tail length and polymer generation, (iii) that although the alkyl tails represent the majority phase in the columnar phases, they form the cylindric domains, and the dendronized polymers occupy the continuous domains. Therefore, upon selective cleavage of the alkyl tails in the columnar phases, the present self-assembly approach may constitute an efficient strategy towards the formation of porous organic matrices with ultra-dense pore size in the range of 2 to 4 nm.

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Ionic Thermotropic Liquid Crystal Dendrimers

Cited by 103 publications

References 42 publications

Novel Phase Morphologies in a Microphase-Separated Dendritic Polymer Melt

Novel Phase Morphologies in a Microphase-Separated Dendritic Polymer Melt

Comblike Liquid-Crystalline Polymers from Ionic Complexation of Dendronized Polymers and Lipids

Functional Columnar Liquid Crystalline Phases From Ionic Complexes of Dendronized Polymers and Sulfate Alkyl Tails

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