Role of main chain rigidity and side-chain substitution on the supramolecular organization of rigid–flexible polymers

Riala, P.; Andreopoulou, Aikaterini K.; Kallitsis, J. K.; Gitsas, Antonis; Floudas, George

doi:10.1016/j.polymer.2006.05.079

Cited by 16 publications

(12 citation statements)

References 35 publications

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“…Correlation distances corresponding to backbones as a function of the molecular mass of the polymer repeat unit are shown in Figure b. Lines with slopes of 1 and 1/2 are indicated that correspond to a layered (1-D) or columnar (2-D) arrangement of backbones. − The data for the three generations suggest the latter arrangement. Hence, the emerging picture of molecular packing is of backbones with a columnar arrangement and with improved backbone–backbone correlations with increasing P n .…”

Section: Resultsmentioning

confidence: 99%

Rheology and Packing of Dendronized Polymers

et al. 2016

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A series of homologous dendronized polymers (DPs) with generations (g) 1−3 and backbone nominal degrees of polymerization (P n ) in the range 50−3000 have been synthesized and characterized in order to investigate the g-and P n -dependent viscoelastic properties and packing of this class of densely grafted, associating and effectively "thick" macromolecules in their molten state. Rheological measurements reveal an unusually long thermal equilibration time, attributed to (i) the tendency of DPs to minimize local density gradients, as realized via their mutual weak interpenetration, and (ii) the intermolecular DP−DP correlations and inter-and intramolecular hydrogen bonding and π−π stacking interactions. With the help of simulations and X-ray scattering measurements, a scenario emerges, according to which DPs interact via local cooperative rearrangements of the dendrons, akin to a Velcro fastening process. In this picture, neighboring bonds accelerate the local interpenetration process. Results from X-ray scattering show increased lateral backbone−backbone correlations with a columnar arrangement of backbones and a liquid crystalline underlying order. Linear viscoelasticity is characterized by plateau moduli which originate from intermolecular bonding and whose extent in frequency and absolute value depends on P n and g and can be lower than or comparable to that of the backbone. Very long relaxation times can be probed (sometimes via creep measurements) and attributed to the lifetime of the bonds. The nonlinear shear rheology data suggest a resemblance in behavior to unentangled linear chains with finite extensibility and point to reduced deformability of the DPs in flow. These findings indicate that DPs constitute a promising class of functional macromolecules with tunable properties.

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Section: Resultsmentioning

confidence: 99%

Rheology and Packing of Dendronized Polymers

et al. 2016

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“…54). [183][184][185][186] Also Lam Sm and correlated layer structures (Col rec phases) were observed if a regular sequence of different building blocks is incorporated in the polymer backbones. 184,187,188 Further reducing the number of lateral chains or reducing their length leads to hexagonal honeycomb structures.…”

Section: Lc Phases Of Rod-like Polymers With Lateral Chainsmentioning

confidence: 99%

Liquid crystal engineering – new complex mesophase structures and their relations to polymer morphologies, nanoscale patterning and crystal engineering

2007

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This critical review focuses on recent progress in the field of T-shaped ternary amphiphiles. These molecules can self-assemble into a series of new liquid crystalline (LC) phases with polygonal cylinder structures, new lamellar phases and LC phases combining columns and layers. These structures are analyzed on the basis of symmetry, net topology and tiling pattern (Laves and Archimedean tilings) and discussed in relation to morphologies of multiblock copolymers, self organized DNA super-lattices, metal-organic frameworks, crystal-engineering and self-assembled periodic superstructures on surfaces (210 references).

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“…For example, in the series of aromatic polyesters, the melting point decreases considerably from 276 to 234 and 156 °C for poly(ethylene terephthalate), poly(tetramethylene terephthalate, and poly(hexa methylene terephthalate) (2,4 and 6 methylene units, respectively) [21]. In the liquid crystalline polymers, the length of the methylene spacers induces important variations in the transition temperatures [22][23][24]. Therefore, it seems particularly important to define the dependence of the thermal properties of poly(alkylene dicarboxylate)s from aliphatic chain length, especially because this kind of study is scarce in literature [25][26][27][28][29].…”

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The effect of aliphatic chain length on thermal properties of poly(alkylene dicarboxylate)s

et al. 2007

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Some poly(alkylene dicarboxylate)s, derived from ethanediol or 1,4-butanediol and different diacids, have been synthesized and analyzed by DSC to determine the correlations existing between the thermal properties and the length of the aliphatic chain. The polymers show crystallization and melting temperatures and enthalpies which increase as the polymethylene segments lengthen, due to the formation of more stable crystals. The samples derived from ethanediol are peculiar; they show reorganization processes during the melting and the melting temperatures are notably higher with respect to those of the other polyesters. This behavior is discussed. Isothermal analysis highlights that poly(alkylene dicarboxylate)s are fast crystallizing polymers. The Avrami analysis suggests a crystallization mechanism characterized by heterogeneous nucleation and three dimensional growth; secondary crystallizations is present only in the samples characterized by short -(CH 2 )-sequences, due to the reorganization of less perfect crystalline forms. A comparative study between the crystallization rates as a function of the undercooling is reported.

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Role of main chain rigidity and side-chain substitution on the supramolecular organization of rigid–flexible polymers

Cited by 16 publications

References 35 publications

Rheology and Packing of Dendronized Polymers

Rheology and Packing of Dendronized Polymers

Liquid crystal engineering – new complex mesophase structures and their relations to polymer morphologies, nanoscale patterning and crystal engineering

The effect of aliphatic chain length on thermal properties of poly(alkylene dicarboxylate)s

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