Details

Autor(en) / Beteiligte

• Kwok, Man-Hin
• Seymour, Bryan T
• Li, Ruipeng
• Litt, Morton H
• Zhao, Bin
• Zhu, Lei

Titel

Tacticity Effect on Mesogen-Free Liquid Crystalline Self-assembly Induced by Strong Dipole–Dipole Interactions

Ist Teil von

• Macromolecules, 2019-05, Vol.52 (10), p.3601-3611

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2019

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Strong dipole–dipole interactions in mesogen-free aliphatic comblike polymers can induce unique liquid crystalline (LC) self-assembly. By comparing atactic and isotactic poly­(oxypropylene)­s with n-alkylsulfonyl side groups (aPOP-SO2C n and iPOP-SO2C n ), the effect of main-chain tacticity on the ordered phase behavior was studied in this work. For aPOP-SO2C n , LC self-assemblies were observed when n is ≥3. Two types of LC phases were formed depending on the side chain length n: (i) a three-dimensional (3D) high-order LC structure (possibly crystal B or E) for n = 3–5 and (ii) a smectic A (SmA) structure for n = 6–12. For iPOP-SO2C n , crystallization was favored as a result of regular main-chain configuration. Only when n ≥ 10, the isotactic comblike polymers exhibited a monotropic phase behavior with the SmA phase appearing during cooling from the isotropic melt. Regardless of atactic or isotactic main chains, these ordered LC and crystalline phases featured a double-layer structure, which was dictated by the optimal dipole–dipole interaction distance (i.e., 0.40–0.44 nm) between sulfonyl groups in the neighboring side chains. This study showed that the chiral centers incorporated in the backbone could not induce chiral smectic self-assembly for the isotactic polymers. As such, we are currently implementing chiral centers in the side chains for the formation of ferroelectric structures for these mesogen-free aliphatic LC polymers.