Evolution of Helical Mesostructures

• Published in: Chemistry : a European journal Vol. 16; no. 5; pp. 1629 - 1637
• Main Authors: Yuan, Pei, Zhao, Lingzhi, Liu, Nian, Wei, Guangfeng, Wang, Yunhua, Auchterlonie, Graeme J., Drennan, J., Lu, Gao Qing, Zou, Jin, Yu, Chengzhong
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.02.2010; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: Architecture; Chemistry; Circularity; electron tomography; Evolution; Formations; Helical; helical structures; Helices; helix-coil transition; Porous materials; Rods; self-assembly; surfactants; Three dimensional
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200902435

An intriguing evolution from a simple internal helix to a hierarchical helical (HH) mesostructure with both internal and external helices or a complicated screwlike and concentric circular (CC) mesostructure is successfully observed. The complicated helical structures are determined by TEM studies and 3D electron tomography. We demonstrate a topological helix–coil transition between the internal and external helices to reveal the origin of the HH mesostructure and the relationship between the straight helical and HH rods. Moreover, the boundary condition of the helix–coil transition is clarified to explain in detail the formation of complex helical structures, such as the screwlike mesostructure. It is proposed that the final structural characteristics are determined exactly by the balance between the decrease in the surface free energy and the maintenance of the hexagonal packing in one individual rod, which explains the formation of unusual CC, HH, and screwlike morphologies in one pot. Our success has opened new opportunities in the characterization of complex porous architectures, thus paving a way to remarkable advances in the fields of synthesis, understanding, and application of novel porous materials. A simple transition: An evolution from a straight internal helical to hierarchical helical (HH) mesostructure with both internal and external helices or screwlike and concentric circular (CC) mesostructures is successfully observed. The HH structures with both internal and external helices are formed during the helix–coil transition process (region I; see picture). Structural mutation occurs in the restricted region (II), thus resulting in the complicated screwlike and CC mesostructures.