Self-Assembly of n-Shaped Rod–Coil Molecules into Thermoresponsive Nanoassemblies: Construction of Reversible Helical Nanofibers in Aqueous Environment

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• 作者：Yuntian Yang ; Junjie Cui ; Zhaohua Li ; Keli Zhong ; Long Yi Jin ; Myongsoo Lee
• 刊名：Macromolecules
• 出版年：2016
• 出版时间：August 23, 2016
• 年：2016
• 卷：49
• 期：16
• 页码：5912-5920
• 全文大小：555K
• 年卷期：0
• ISSN：1520-5835

文摘

Amphiphilic coil–rod–coil molecules 1–3, consisting of an n-shaped rod building block and poly(ethylene oxide) (PEO) with a degree of polymerization of 5 linked through a biphenyl unit as the coil segment, were synthesized. Molecule 1 self-assembles into lamellar and hexagonal perforated layer structures, in the crystalline and liquid crystalline phases, respectively. Remarkably, molecule 2 incorporating lateral methyl groups between the rod and coil segments spontaneously self-organizes into hexagonal perforated layer and oblique columnar structures. The additional incorporation of a lateral butyl group at the center of the rod segment of molecule 2 generates molecule 3, which assumes an exclusively oblique columnar structure in the solid state. In aqueous solutions, molecule 1 self-assembles into fibrous aggregates, whereas molecules 2 and 3 exhibit a self-organizing capacity to form helical fibers. Additionally, circular dichroism (CD) experiments and atomic force microscope (AFM) measurements of molecule 3 highlight a switch of the helical sense to the opposite handedness, depending on the temperature of the aqueous solution.