Polymer thin films with tailored porous structure providing desired color and other optical characteristics are of great interest due to resistance to shading and structural changes compared to polymer films filed with pigments and dyes. Pores with tailored structure and dimensions serving as ‘air-borne pigment’ nanoparticles incorporated in a polymer matrix of such thin films provide desired color/optical effects via trapping and scattering light of selected spectral regions at the polymer-air interface. We demonstrate in this work a novel concept of facile preparation of such thin films based on polymer blends and block co-polymers with in-situ incorporation of ‘air-borne pigments’ by direct immersion of the films in a mixture of organic solvents. The formation of the desired structure in this study is shown for the films based for selected compositions of blends of polystyrene (PS), poly-2-vynilpyrrolydone (P2VP) and their block copolymers, flow-coated on silicon substrates. Annealing of the films in a mixture of n-heptane and isopropyl alcohol provides partial dissolving of the P2VP domain and relaxation of PS chains resulting in formation of the ‘air-borne pigment’. This approach was applied to produce films of white and blue colors based on distinct polymer compositions and preparation, and can be potentially extended to designing films with other optical characteristics. The demonstrated method is fast, as well as it has other benefits, such as its applicability to preparation of films on thermal sensitive substrates and possibility for scaling-up.

Structural color with "air-borne pigments" via direct immersion annealing (DIA) of polymer thin films

256th National Meeting (2018)

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