Nature has engineered universal, catechol-containing adhesives which can be synthetically mimicked in the form of polydopamine (PDA). In this study, PDA was exploited to enable the formation of block copolymer (BCP) nanopatterns on a variety of soft material surfaces. While conventional PDA coating times (1 h) produce a layer too rough for most applications of BCP nanopatterning, we found that these substrates could be polished by bath sonication in a weakly basic solution to form a conformal, smooth (root-mean-square roughness ∼0.4 nm), and thin (3 nm) layer free of large prominent granules. This chemically functionalized, biomimetic layer served as a reactive platform for subsequently grafting a surface neutral layer of poly(styrene-random-methyl methacrylate-random-glycidyl methacrylate) to perpendicularly orient lamellae-forming poly(styrene-block-methyl methacrylate) BCP. Moreover, scanning electron microscopy observations confirmed that a BCP nanopattern on a poly(ethylene terephthalate) substrate was not affected by bending with a radius of ∼0.5 cm. This procedure enables nondestructive, plasma-free surface modification of chemically inert, low-surface energy soft materials, thus overcoming many current chemical and physical limitations that may impede high-throughput, roll-to-roll nanomanufacturing.
Bibliographical noteFunding Information:
C.J.E. thanks the Welch Foundation (grant # F-1709), DuPont Young Professor Award, 3M Nontenured Faculty Award and the Norman Hackerman Advanced Research Program (grant # ARP-003658-0037-2011) for partial financial support. J.H.C. acknowledges partial financial support from LG Chem Graduate Research Fellowship and Graduate Dean's Prestigious Fellowship Supplement. R.K. thanks the Takenaka Scholarship Foundation and Dr. Thomas F. Edgar Endowed Graduate Fellowship in Chemical Engineering for financial support. The findings and conclusions in this paper have not been formally disseminated by the Food and Drug Administration and should not be construed to represent any agency determination or policy. The mention of commercial products, their sources, or their use in connection with material reported herein is not to be construed as either an actual or implied endorsement of such products by the Department of Health and Human Services.
© 2016 American Chemical Society.
- block copolymer (BCP)
- conformal coating
- flexible substrates
- polydopamine (PDA)
- solution deposition
- surface modification