American Chemical Society
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pH-Induced Antireflection Coatings Derived From Hydrogen-Bonding-Directed Multilayer Films

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journal contribution
posted on 2010-11-16, 00:00 authored by Yingxi Lu, Yeon Joo Choi, Ho Sun Lim, Donghoon Kwak, Chiyeoung Shim, Seung Goo Lee, Kilwon Cho
Hydrogen-bonding-directed layer-by-layer assembled films, based on polystyrene-block-poly(acrylic acid) (PS-b-PAA) block copolymer micelles and poly(4-vinylpyridine) (P4VP), were successfully fabricated in methanol. Varying the PAA content in the PS-b-PAA micelles afforded control over the film growth properties, especially the multilayer film thickness. Interestingly, antireflection films with refractive indices that could be tuned between 1.58 and 1.28 were obtained by treatment with an aqueous HCl solution (pH 2.27), and the transmittance obtained was as high as 98.4%. In acid solution, the pyridine group was protonated, destroying the hydrogen bonding between P4VP and PAA. A concomitant pH-induced polymer reorganization in the multilayers resulted in a porous honeycomb-like texture on the substrate.