Lamellar Liquid Crystals of In‐Plane Lying Rod‐Like Mesogens with Designer Side‐Chains: The Case of Sliding versus Locked Layers

Abstract

The dimensionality of self-assembled nanostructures plays an essential role for their properties and applications. Herein, an understanding of the transition from weakly to strongly coupled layers in soft matter systems is provided involving in-plane organized π-conjugated rods. For this purpose, bolaamphiphilic triblock molecules consisting of a rigid biphenyl core, polar glycerol groups at the ends, and a branched (swallow-tail) or linear alkyl or semiperfluoroalkyl chain in lateral position have been synthesized and investigated. Besides weakly coupled lamellar isotropic (Lam ), lamellar nematic (Lam ) and sliding lamellar smectic phases (Lam ), a sequence of three distinct types of strongly coupled (correlated) lamellar smectic phases with either centered (c2mm) or non-centered rectangular (p2mm) lattice and an intermediate oblique lattices (p2) were observed depending on chain length, chain branching and degree of chain fluorination. This new sequence is explained by the strengthening of the layer coupling and the competition between energetic packing constraints and the entropic contribution of either longitudinal or tangential fluctuations. This example of directed side chain engineering of small generic model compounds provides general clues for morphological design of two-dimensional and three-dimensionally coupled lamellar systems involving larger π-conjugated molecular rods and molecular or supramolecular polymers, being of actual interest in organic electronics and nanotechnology.

Flavylium Salts: A Blooming Core for Bioinspired Ionic Liquid Crystals

“…The occurrence of the Lam Col phase can be rationalized by the strong tendency for the formation of vertical aggregates of the flavylium cation and a weak layer coupling . At high temperatures the stacking is unfavorable, therefore the calamitic shaped molecules form a SmA phase as expected.…”

A Self‐Assembled Bicontinuous Cubic Phase with a Single‐Diamond Network

“…[a] Determined by DSC second heating scan, 10 K min −1 . Abbreviations: Cr=crystalline solid, =SD cubic phase with symmetry; =DG cubic phase with symmetry; p 2=honeycomb LC phase with p 2 lattice; Lam Sm =lamellar phase with coplanar bundles and periodicity in the layers; Iso=isotropic liquid; for DSCs, see Figure S1; for XRD data, see Tables S1 and S2.…”

“…Ia " 3d = DG cubic phase with Ia " 3d symmetry; p2 = honeycomb LC phase with p2lattice; [22] Lam Sm = lamellar phase with coplanar bundles and periodicity in the layers; [23] Iso = isotropic liquid;for DSCs, see Figure S1; for XRD data, see Tables S1 and S2. Figure S4d).…”

I22: SAXS/WAXS beamline at Diamond Light Source – an overview of 10 years operation

“…These are characteristic of living organisms and also many complex materials such as polymers and colloids. Relevant active research in the UK encompasses the fields of medicine (Ma et al, 2016;Burton et al, 2019;Coudrillier et al, 2016;Al-Jaibaji et al, 2018;Kudsiova et al, 2019), biology (Troilo et al, 2016;McGeehan et al, 2011;Arnold et al, 2011;Salamah et al, 2018), the environment (Neill et al, 2018;Seddon et al, 2016) and materials (Summerton et al, 2019;Wychowaniec et al, 2018;Burton et al, 2017), and includes studies of supramolecular organization in biomechanical systems (Xi et al, 2018;Kampourakis et al, 2018;Sui et al, 2014), corneal transparency (Morgan et al, 2018;Hayes et al, 2017), biological membranes (Barriga et al, 2016;Slatter et al, 2018;, polymer processing (Stasiak et al, 2015;Wan et al, 2018;Heeley et al, 2013;Toolan et al, 2017), colloids (Calabrese et al, 2019;Poulos et al, 2016;Mable et al, 2016), inorganic aggregates (Raine et al, 2018;Bennett et al, 2015;Zhou et al, 2018), liquid crystals (Hallett et al, 2014;Prehm et al, 2018;Lehmann et al, 2018) and devices (Xia et al, 2018;Barrows et al, 2016).…”