Sheetlike Side-Chain Liquid Crystalline Polyacetylenes Forming Monolayer Lamellae in Dilute Solutions

Abstract

Self-assembly behaviors of a series of hydrophobic side-chain liquid crystalline (LC) polyacetylenes, namely, poly(5-{[(4‘-alkoxy-4-biphenylyl)carbonyl]oxy}-1-pentyne)s [P-3,m (m = 5, 7, 9)], were studied in dilute solutions. The assembly was induced by tuning the solvent property to be selective for the alkyl tails on the side chains, with the processes characterized by turbidity, dynamic light scattering, 1H NMR, and excitation fluorescence anisotropy measurements. The morphology and structure of the P-3,m aggregates formed in the solutions were investigated using atomic force microscopy and wide-angle X-ray diffraction. The experimental results indicate that the P-3,m polymers can form monolayer lamellae in selective solvents. In the lamella, the P-3,m molecules are sheetlike and pack parallel to each other with their backbones located in the lamellar center and their alkyl tails covering the top and bottom lamellar surfaces. The lamellar thickness is largely determined by the width of the molecular sheet. When the solvent becomes selective for the tails, the P-3,m chains may undergo shape stiffening to become more sheetlike.

DFT Study on the Effect of Different Peripheral Chains on Charge Transport Properties of Triphenylene Derivatives

“…The introduction of liquid-crystalline pendants to the conjugated polyacetylene backbones has attracted much attention because the resulting offspring may be both light emitting and liquid crystalline, which may offer an array of exciting opportunities for high-tech innovations. [12][13][14] Although the disubstituted (RC＝CR') n polymers have been reported to exhibit higher thermal stability, higher glass transition temperatures and higher luminescence efficiency than monosubstituted polymers (CH＝CR) n , the latter are studied much more because they can be polymerized easier. 12 Our research team has synthesised several monomers of polyacetylene containing triphenylene.…”

Liquid crystalline conjugated polymers and their applications in organic electronics

“…These sheet-like side chain LC PAs can form monolayer lamellae in dilute solution. 37 The mono-substituted PAs bearing ferroelectric LC groups can also show chiral nematic and smectic phases under LC state. 38 In addition to PAs, many other conjugated polymers incorporating with LC side groups have also been synthesized and characterized.…”

Molecular Shapes of Monosubstituted Polyacetylenes in their Liquid Crystalline Phases

“…Later on, we found that this sheet-like SCLCPA, in solvents selective for the alkyl tails, can selfassemble into monolayer lamellae with thickness nearly identical to the molecular width. [76] In order to form an LC phase using the building block of the whole sheet-like SCLCPA molecules rather than only the side-chains, one may intuitively consider that the flexible spacer is not necessary. The rigid mesogenic moieties can be directly linked to the PA backbone without spacer.…”