Synergy Effect on Morphology Switching: Real‐Time Observation of Photo‐Orientation of Microphase Separation in a Block Copolymer

Abstract

Linear polarisiertes Licht (LPL) verursacht zeitauflösenden Messungen der Synchrotron‐Röntgenstreuung zufolge eine Reorientierung phasengetrennter mesoskopischer amorpher Zylinder in einer lichtresponsiven Flüssigkristallin(LC)‐Matrixdomäne eines Diblockcopolymers (siehe Schema). Dabei kommt es zu kooperativen und synchronen Bewegungen der LC‐Schicht (auf Molekülebene) und der Polymerdomänen (auf mesoskopischer Ebene).

Liquid‐Crystalline Polymer and Block Copolymer Domain Alignment Controlled by Free‐Surface Segregation

“…GI‐XRD measurements similarly revealed that the addition of PBMA‐ b ‐PAz and annealing drastically changes the orientation of the smectic layer ( d =3.6 nm), as shown in Figure 2 c and d. The MPS cylindrical pattern within the PBMA‐ b ‐PAz (10 %)/PS‐ b ‐PAz film are oriented parallel to the substrate following the Az mesogen alignment 14b,c…”

“…The GI‐XRD results indicate the existence of more ordered, vertically aligned smectic layers in the film when the direction of the X‐ray beam incidence was set orthogonal to the actinic LPL direction (Figure 3 c and d). 14b, 19…”

Liquid‐Crystalline Polymer and Block Copolymer Domain Alignment Controlled by Free‐Surface Segregation

“…We demonstrate here that the coverage of the surface with the free-surface-active polymer leads to a homeotropic-to-parallel orientation change of LC mesogens, which further leads to an efficient in-plane photoalignment of microphase separation (MPS) domains of a relevant LC block copolymer by linearly polarized light (LPL). [14] With regard to the MPS alignment control, the important role of a top coat layer has recently been demonstrated by Bates et al [15] In this case, a polar-to-nonpolar chemical conversion of the top layer is achieved to fulfill the requirement of spin-casting from an aqueous solvent and to provide a neutral (non-preferential) layer for the hydrophobic block copolymer during the annealing. In the present approach, in contrast, no additional coating procedure is required, providing a simple, versatile method for the desired alignment control of MPS domains.First, the alignment behavior of an LC azobenzene (Az) homopolymer (PAz in Figure 1 a; M n = 8.0 10 4 , M w /M n = 1.13, and g-43 8C-SmC-100 8C-SmA-120 8C-iso) was examined.…”

Free Surface-Induced Planar Orientation in Liquid Crystalline Block Copolymer Films: On the Design of Additive Surface Active Polymer Layer

“…However, it is already confirmed that the information at the molecular level obtained by spectroscopic evaluation can be directly related to the orientation of cylinder MPS cylinder domains at the mesoscopic level. It is well established by X-ray measurements and atomic force microscopy that the mesogenic orientation and the MPS domain orientations are parallel with each other to minimize the elastic energy of the system [5][6][7][8][9]12]. Therefore, the total hierarchical structures including Az mesogens and polystyrene cylinder domains should be controlled in the film as displayed in Scheme 1.…”

“…The photoalignment technique leads to static uniform orientational inductions of MPS structures [5][6][7][8] and further to dynamic rewritable functions [9]. We have demonstrated such dynamic rewritable photoalignment controls by using a block copolymer of poly(butyl methacrylate) (PBMA) connected with an azobenzene (Az)-containing liquid crystalline (LC) polymer (PBMA-b-P5Az10MA, see Scheme 2).…”