COMPETITION BETWEEN LIQUID CRYSTALLINITY AND BLOCK COPOLYMER SELF ASSEMBLY IN CORE-SHELL ROD-COIL BLOCK COPOLYMERS
Block copolymer (BCP) self assembly offers a simple and controllable means to obtain nanostructures with typical orders on the scale of ~5-100 nm. Liquid crystals (LCs) are one class of soft materials that undergo self organization at 1-10 nm. Incorporating LCs as one of the blocks in a BCP results in LCBCPs that possess both structural hierarchy and functionality. One unique type of LCBCP is the rodcoil BCP (RCBCP), in which one block adopts a rigid rod-like conformation. Several factors affect the thermodynamic behavior of these systems, including X (Flory Huggins parameter), N (degree of polymerization), f(volume fraction of each block), the order parameter of the macromolecular mesogen, and the area per junction of the rod (Arod) and the coil (Acod). Novel self assembling behaviors with complex phase structures different from the coil-coil systems have been observed. In general, at symmetric volume fractions, lamellar morphology is prevalent. At asymmetric volume fractions, morphologies with highly curved interfaces such as sphere (S) or gyroid (G) have only been observed in low molecular mass rod-coil systems. As the molecular weight of the rod increases, the rigid rod becomes incompatible with the curved inter-material dividing surface (IMDS) dictated by S or G phases; there thus exists competition between liquid crystallinity of the rods and BCP self assembly. Most of the reported work showed that liquid crystallinity dominated the phase behavior and the S or G phase was often degenerated into structures with planar IMDS such as zig-zag, arrow-head, mushroom, perforated lamellae, etc. This is because the interaction between the rods is relatively strong and LC ordering dominates the ordering process. Thus, we hypothesize that in a rCBCP system with relatively weak LC interactions, BCP self assembly could dominate the overall phase structure.
Kishore K.Tenneti Xiaofang Chen Christopher Y.Li Xinhua Wan Xinghe Fan Qi-Feng Zhou Lixia Rong Benjamin S.Hsiao
A.J.Drexel Nanotechnology Institute and Department of Materials Science and Engineering,Drexel Unive Department of Polymer Science and Engineering and The Key Laboratory of Polymer Chemistry and Physic Department of Chemistry,Stony Brook University,Stony Brook,New York 11794
国际会议
International Symposium on Polymer Physics(2008年国际高分子物理学术会议PP2008)
厦门
英文
27-28
2008-06-08（万方平台首次上网日期，不代表论文的发表时间）