Photo-directing chemoepitaxy: the versatility of poly(aryl methacrylate) films in tuning block copolymer wetting

• Published in: Polymer chemistry Vol. 12; no. 21; pp. 321 - 329
• Main Authors: Zhao, Jiacheng, McCallum, Francis J, Yu, Ye, Fu, Changkui, Kaitz, Joshua A, Cameron, James F, Trefonas, Peter, Blakey, Idriss, Peng, Hui, Whittaker, Andrew K
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 07.06.2021
• Subjects: Aromatic compounds; Block copolymers; Crosslinking; Domains; Exposure; Lamella; Lamellar structure; Orientation; Polymer chemistry; Polymer films; Polymethyl methacrylate; Polystyrene resins; Self-assembly; Spin coating; Tuning; Ultraviolet radiation; Versatility; Wetting
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/d1py00501d

Photo-directed orientation control of block copolymer (BCP) domains is a powerful method for generating distinct regions of perpendicular and parallel-aligned lamella in a single film layer. In this study we demonstrate the versatility of aromatic methacrylate polymer films for tuning the wetting behaviour of PS- b -PMMA films on UV exposure. Poly(aryl methacrylate) films with excellent thermal and solvent stability were obtained by thermal crosslinking of spin-coated films. Upon exposure to UV light (254 nm), the surface polarity of the films changed as a result of the photo-Fries rearrangement of the aromatic ester groups. Following UV exposure to appropriate doses, the irradiated poly(aryl methacrylate) films can induce a change in the orientation of the domains of an overlayer of PS- b -PMMA from parallel to perpendicular lamellar structures. Patterning with a photomask enables generation of high fidelity BCP microdomain regions with targeted orientation. It is worth noting that the UV dose required to induce lamellar orientation in a wide range of BCP films can be tailored by rational selection of the poly(aryl methacrylate), suggesting outstanding flexibility in controlling BCP wetting behaviour. This simple, rapid, cost-effective and flexible approach to controlling BCP orientation makes poly(aryl methacrylate)s extremely promising for block copolymer self-assembly applications. UV irradiated poly(aryl methacrylate) films can induce a change in the orientation of the domains of an overlayer of PS- b -PMMA from parallel to perpendicular lamellar structures.