Liquid Crystalline Assembly of a Diblock Rod−Coil Polymer Based on Poly(ethylene oxide) and Its Complexes with LiCF3SO3

• Published in: Macromolecules Vol. 29; no. 17; pp. 5567 - 5573
• Main Authors: Lee, Myongsoo, Oh, Nam-Keun, Lee, Hwan-Koo, Zin, Wang-Cheol
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 12.08.1996
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Thermal and thermodynamic properties; End group; Thermotropic state; Mesomorphic state structure; Experimental study; Oligomer; Complexes; Liquid crystals; Phase transitions; Sulfonate; Ethylene oxide polymer; Molecular assembly; Biphenyl derivatives; Diester; Concentration effect; Lithium compound
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma951418y

The rod−coil polymer of ethyl 4-[4‘-oxy-4-biphenylylcarbonyloxy]-4‘-biphenylcarboxylate with poly(ethylene oxide) with a degree of polymerization of 12 (12-4) was observed to exhibit a microphase-separated lamellar structure with nanoscale dimension and to melt into a layered smectic A mesophase. The complexes of 12-4 with 0.05−0.8 mol of LiCF3SO3 per ethylene oxide unit of a molecule were also prepared in order to investigate mesomorphic phase changes of 12-4 upon complexation. An abrupt mesophase change was observed for the entire range of salt concentrations. The complexes with 0.05−0.2 mol of LiCF3SO3 display an enantiotropic smectic A phase as their highest temperature mesophase. From the complex with 0.2 mol of LiCF3SO3, an enantiotropic cubic phase is induced and a smectic A phase disappears at the complex with 0.25 mol of LiCF3SO3, which displays a cubic mesophase only. The complex with 0.3 mol of LiCF3SO3 also exhibits an enantiotropic cubic phase; however, it exhibits a cylindrical micellar mesophase as its highest temperature mesophase, contrary to the complexes with up to 0.25 mol of LiCF3SO3. The complexes with 0.4−0.7 mol of LiCF3SO3 exhibit only a cylindrical micellar mesophase, and the complex with higher salt concentration becomes amorphous. These results, characterized by a combination of differential scanning calorimetry, optical polarized microscopy, and X-ray scattering experiments, are discussed.