Liquid-crystalline polymers (LCPs) have been extensively studied as advanced functional materials because of their useful properties, such as their self-organizing nature, the fluidity of long-range order, their cooperative motions, and their anisotropy in various physical properties.[1] The combination of LCPs with microphase-separated block copolymers has given the designed materials some interesting features. [2][3][4] Furthermore, periodic nanostructures may be formed by the interplay processes between the microphase separation and the regular periodicity of LC ordering, [5,6] which are known as supramolecular cooperative motions (SMCMs). It is widely known that ordered microphase structures can be formed in well-defined block copolymers, [7][8][9][10][11][12][13][14][15][16] which can be used as templates for the fabrication of novel nanostructured materials. Unfortunately, perfect domain order over a large area cannot be achieved by molecular self-assembly alone. Recent progress in block copolymers has concentrated on the control of such microphase-separated structures on a macroscopic scale: electric or magnetic-field, [7][8][9] temperature-gradient, [10] crystallization, [11] modified-substrate-surface, [12,13] shearing, [14] solvent-evaporation, [15] and roll-casting [16] methods have been explored for obtaining long-range order. Although introduction of LC ordering to act on the microphase-separated structures might provide a new opportunity to control nanoscopic ordered structures, SMCMs have not yet been adopted as a control method. Here, we report a simple rubbing technique combined with the SMCMs to align three-dimensional nanocylinder phase domains in an amphiphilic diblock LC copolymer. As shown in Figure 1, an amphiphilic diblock LC copolymer consisting of poly(ethylene oxide) (PEO) and polymethacrylate (PMA) containing an azobenzene (Az) moiety in the side chain, PEO 114 -b-PMA(Az) 51 , was used to study the microphase-separated structures. Typical transmission electron microscopy (TEM) images of annealed copolymer films without rubbing treatment show nanocylinders aligned perpendicular to the film surface with a diameter of 10 nm, dispersed in an Az LC matrix with a periodicity of 24 nm (Fig. 1B).A mechanical rubbing method, one of the most popular techniques for aligning LCs, has been used to control lowmolecular-weight compounds, LC polymers, and cross-linked LC gels. [17,18] Here, we first used this method combined with SMCMs to manipulate nanostructures of the amphiphilic diblock LC copolymer. Copolymer films with a thickness of about 200 nm were treated by a rubbing technique, as shown in Figure 1C. After annealing, a large anisotropic absorption was observed in the polarized UV-vis spectra shown in Figure 2A, indicating that the homogeneous LC alignment was achieved parallel to the rubbing direction. An order parameter (S) of 0.57 was obtained at 332 nm from Equation 1:where A ʈ and A ⊥ are the absorbance parallel and perpendicular to the rubbing direction, respectively. Such highly orde...
