Photoinduced Modulation of Polymeric Interfacial Behavior Controlling Thin-Film Block Copolymer Wetting

Abstract

The tunable surface-wetting properties of photosensitive random copolymer mats were used to spatially control the orientations of thin-film block copolymer (BCP) structures. A photosensitive mat was produced via thermal treatment on spin-coated random copolymers of poly­(styrene-ran-2-nitrobenzyl methacrylate-ran-glycidyl methacrylate), synthesized via reversible-deactivation radical polymerization. The degree of UV-induced deprotection of the nitrobenzyl esters in the mat was precisely controlled through the amount of UV-irradiation energy imparted to the mat. The resulting polarity switching of the constituents collectively altered the interfacial wetting properties of the mat, and the tunability allowed lamellar or cylinder-forming poly­(styrene-b-methyl methacrylate) BCP thin films, applied over the mat, to change the domain orientation from perpendicular to parallel at proper UV exposures. UV irradiation passing through a photomask was capable of generating defined regions of BCP domains with targeted orientations.

Distributions of Deuterated Polystyrene Chains in Perforated Layers of Blend Films of a Symmetric Polystyrene-block-poly(methyl methacrylate)

“…The main reason is that the perpendicular orientation is only favored on substrates with a neutral surface, which has no affinity to both PS and PMMA. It has been well known that the neutralization of the substrate interface relies on grafting a thin layer of random copolymers, depositing a thin sheet of reduced graphene oxide, or a thin mat of cross-linkable homopolymers. − , …”

“…It has been well known that the neutralization of the substrate interface relies on grafting a thin layer of random copolymers, depositing a thin sheet of reduced graphene oxide, or a thin mat of cross-linkable homopolymers. [27][28][29][30][31][32][33][34]44 To obtain structural information in a reciprocal space, the same films shown in Figure 1 were characterized by both GISAXS and GISANS. Figure 4 shows the resultant GISAXS patterns.…”

“…Furthermore, domain orientations and chain conformations near the substrate interface are different from those far from the substrate interfaces when thin films are supported by a solid substrate. − For example, an attractive substrate inevitably favors the parallel orientation of self-assembled nanodomains and specific adsorption of a wetting layer on it. To prevent the effect of the substrate interface, much effort has been devoted to finely neutralize the substrate interface with surface modifiers, which can effectively grow perpendicularly oriented nanodomains in thin films. − …”

Photoimageable Organic Coating Bearing Cyclic Dithiocarbonate for a Multifunctional Surface

“…These functionalities can also be dynamically altered via chemical transformations, thus expanding their potential range of applications. The fine-tuning of surface wettability is a good example of such a strategy, as it allows the control of the self-assembly behavior of thin films comprising overlying block copolymer. , Other design strategies include the modification of the dielectric surface (which can improve the performance of organic thin-film transistors), − the grafting of hydrophilic zwitterionic polymer brushes (which is used for the formation of antifouling or antibacterial surfaces), − and the immobilization of oligopeptides with specific sequences onto the surface of the polymeric layer (which is used for the enhancement of cell adhesion). , …”

Recent Trends in Applying Ortho-Nitrobenzyl Esters for the Design of Photo-Responsive Polymer Networks

“…Several works have shown the influence of the substrate on the orientation of the structure domains of a coated block co-polymer [104,105]. In a recent work, Sol and co-workers [106] proposed an interesting approach in order to control the domains' orientation of a coated co-polymer blocks, by photo-controlling the substrate wettability. They fabricated a substrate with photo-responsive wettability based on a block copolymer of poly(styrene-r-2-nitrobenzyl methacrylate-r-glycidyl methacrylate).…”