Frustrated self-assembly of dendron and dendrimer-based supramolecular liquid crystals

Mezzenga, Raffaele; Ruokolainen, Janne; Canilho, Nadia; Kasëmi, Edis; Schlüter, D.; Lee, Won Bo; Fredrickson, Glenn H.

doi:10.1039/b814972k

Cited by 44 publications

(57 citation statements)

References 33 publications

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“…choice of non-covalent bonding type(s), side-groups, and macromolecular template chemistry and architecture). 6 Regarding this last choice, much recent work has focused on complexes involving macromolecular templates with even more complicated architectures, such as dendrimers, 14,15 hyperbranched polymers, 16 dendronized polymers, [17][18][19] and rod-coil block copolymers. [20][21][22] Nandan et al have recently reported hierarchically organized materials formed by complexation of amphiphilic surfactants with heteroarm star (HAS) and block-arm star (BAS) polymers composed of polystyrene (PS) and poly(2-vinylpyridine) (PVP).…”

Section: Introductionmentioning

confidence: 99%

Hierarchical self-organization in polyelectrolyte-surfactant complexes based on heteroarm star block copolyampholytes

Hammond

Tsitsilianis

et al. 2009

Soft Matter

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A novel heteroarm star block terpolymer bearing short polystyrene (PS) arms and an equal number of longer poly(2-vinylpyridine)-block-poly(acrylic acid) (P2VP-b-PAA) arms was used as the macromolecular template component in polyelectrolyte-surfactant supramolecular complexes. The ampholytic nature of this novel star block copolymer allowed complexation to be carried out on either the P2VP blocks (with negatively charged surfactants) or on the PAA blocks (with positively charged surfactants), depending only on the pH at which the complexation reaction was carried out. The various complexes displayed self-organization on both the length scale of the polyelectrolyte-surfactant complexes (ca. 3.5-4 nm) and on the length scale of the overall heteroarm star block copolymer (18-39 nm, depending on which block had been complexed). Addition of surfactants to one block versus the other results in dramatically different morphologies; when the P2VP blocks are complexed, closepacked spheres are observed, while when the PAA blocks are complexed, the material forms core-shell cylinders (PS and P2VP composing the core and shell, respectively) in a matrix of PAA(surfactant). The morphologies are discussed by combining both real-space techniques, such as transmission electron miscroscopy, and reciprocal space techniques, such as X-ray scattering at small and large angles.

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Section: Introductionmentioning

confidence: 99%

Hierarchical self-organization in polyelectrolyte-surfactant complexes based on heteroarm star block copolyampholytes

Hammond

Tsitsilianis

et al. 2009

Soft Matter

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“…[2][3][4][5][6] Dendrons, dendrimers, and dendronized polymers have emerged as unmatched building blocks for supramolecular polymer science. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] These highly branched molecules are of unique interest because their typical size and the number of peripheral groups, which participate in supramolecular interactions, can be designed by simply changing their generation. 7 These macromolecular templates have an intrinsic "concave" curvature at the dendritic surface with respect to the focal point, which has led previous studies on the self-assembly of dendrons and dendrimerbased systems to the assumption that this concave dendrimer/ pendant chain interface is maintained in the bulk structures.…”

Section: Introductionmentioning

confidence: 99%

Controlling Hierarchical Self-Assembly in Supramolecular Tailed-Dendron Systems

et al. 2010

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We study the self-assembly of a dendritic macromolecular system formed by a secondgeneration dendron with pH-responsive end groups and with a polymer chain emanating from its focal point, typically referred to as dendron-coil system. We use supramolecular ionic interactions to attach to the periphery of the dendrons sulfate-terminated alkyl tails of various lengths. The resulting ionic complexes have a molecular architecture similar to a four-arm dendritic pitchfork with varying arms and holder lengths. The bulk morphologies observed by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) show thermodynamically stable, hierarchical "inverted" hexagonal or lamellar structures. In addition, for a specific range of volume fractions, we show order-to-order transitions associated with the melting of the crystalline alkyl tails. The structural models for the molecular packing emerging from TEM and SAXS analysis are benchmarked to available self-consistent field theories (SCFTs) developed for identical systems and experiments and theoretical predictions are found in perfect agreement. With respect to our previous work on inverted dendron and dendrimer-surfactant self-assembled morphologies (Mezzenga et al. Soft Matter. 2009, 5, 92-97), the present findings show that keeping the same dendritic molecular architecture but adding a polymer chain emanating from the focal point enables the scale up of the structural organization from the liquid crystalline length scale (10 0 nm) to the block copolymer length scale (10 1 nm) while preserving the inverted unconventional morphologies. Because the length of the holder and the arms of the dendritic pitchfork can be finely tuned, these systems offer new possibilities in the design of nanostructured organic materials and their use in templating applications.

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“…Thus, dendrimers of lower generation have relatively loose inner structure while higher generations are densely packed and organized. [1][2][3][4] These particular organizations result in unusual properties, as for example liquid-crystalline behavior at high concentrations, 5,6 anomalous intrinsic viscosity, 7,8 and a multivalent molecular surface. 9,10 As a consequence, dendrimers have been proposed for very useful applications, as for example, drug-delivery systems, 11,12 gene vectors, 13,14 catalysts 15,16 and organic light-emitting diodes.…”

Section: Introductionmentioning

confidence: 99%

“…Dendrimers are the more widely investigated polymers [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and consist of perfectly branched molecules made of tree-like fragments (dendrons) attached to a central core. The internal organization and size of these welldefined, often monodisperse, molecules depends on the generation number, g, of dendrons.…”

Section: Introductionmentioning

confidence: 99%

Internal organization of macromonomers and dendronized polymers based on thiophene dendrons

et al. 2015

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The internal organization of macromonomers (MGs) consisting of all-thiophene dendrons of generation g= 2 and 3 attached to a phenyl core, as well as of the dendronized polymers resulting from polymerization of these macromonomers (PG2 and PG3, respectively), has been investigated using theoretical methods. The conformational preferences of the MGs, determined using density functional theory calculations, are characterized by the relative orientation between dendrons and core.We find that the strain of the MGs increases with the generation number and is alleviated by small conformational re-arrangements of the peripheral thiophene rings.The conformations obtained for the MGs have subsequently been used to construct models for the dendronized polymers. Classical molecular dynamics simulations have evidenced that the interpenetration of dendrons belonging to different repeat units is very small for PG2. In contrast, the degree of interpenetration is found to be very high for PG3, which also shows a significant degree of backfolding (i.e. occurrence of peripheral methyl groups approaching the backbone). Consequently, PG2 behaves as a conventional linear flexible polymer bearing bulk pendant groups, whereas PG3 is better characterized as a semirigid homogenous cylinder. The two polymers are stabilized by - stacking interactions, even though these are significantly more abundant for PG3 than for PG2; the average number of interactions per repeat unit is 3.0 and 8.8 for PG2 and PG3, respectively. While in these interactions the thiophene rings can adopt either parallel (sandwich) or perpendicular (T-shaped) dispositions, the former scenario turns out to be the most abundant.3

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Frustrated self-assembly of dendron and dendrimer-based supramolecular liquid crystals

Cited by 44 publications

References 33 publications

Hierarchical self-organization in polyelectrolyte-surfactant complexes based on heteroarm star block copolyampholytes

Hierarchical self-organization in polyelectrolyte-surfactant complexes based on heteroarm star block copolyampholytes

Controlling Hierarchical Self-Assembly in Supramolecular Tailed-Dendron Systems

Internal organization of macromonomers and dendronized polymers based on thiophene dendrons

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