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BIOMIMETIC NON-IRIDESCENT STRUCTURAL COLORATION VIA PHASE-SEPARATION OF COMPATIBILIZED POLYMER BLEND FILMS

Nallapaneni, Asritha
http://rave.ohiolink.edu/etdc/view?acc_num=akron1590749223865508

Abstract Details

2020, Doctor of Philosophy, University of Akron, Polymer Engineering.
Colors are ubiquitously present in nature and are used in several day-to-day applications such as paints, textiles, cosmetics and displays. Most of these colors are pigment-based and suffer from non-environment friendliness, toxicity and non-tunability. Structural colors have received significant attention as alternatives to degradation-prone pigment-based colors. Many non-iridescent (angle-independent) structural colors in nature are produced from porous bio-polymer nanostructures with multi-functional properties such as UV-protection and hydrophobicity. However, most bioinspired synthetic non-iridescent structural colors have been attained via self-assembly of colloids and 3D printing, but they suffer from poor adhesion and robustness. Non-iridescent structural colors in nature, on the other hand, are produced from quasi-ordered porous nanostructures and are thought to form by polymeric phase separation but have not yet been achieved artificially despite their advantages including scalability. The objective of this dissertation is to develop a polymeric phase-separation process that results in non-iridescent structural coloration. Here, we report, for the first time, fabrication of non-iridescent structural colors from porous polymers via temperature-induced phase-separation of compatibilized polymer blend films. By simply tuning the molecular parameters such as composition of the polymer blend (ϕ), the color of the films can be tuned from white to blue to transparent with underlying morphological transitions from a disordered to a quasi-ordered state. Control on brightness and color saturation can be achieved by tuning optical interfaces and structural order respectively at a molecular level without using any additives by tuning molecular weight of homopolymers and block co-polymer. Gradient non-iridescent structural colors were attained from films of differential thickness via tunable coffee ring effect. We further examined the absence of green and red colors via time-resolved optical and morphological analysis and the results suggested that loss of structural order (ξ0) with increase in domain size (d) because of Ostwald ripening during late stage of phase-separation is the key underlying phenomenon. Our preliminary results demonstrated that by utilization of polymer blend nanocomposites, we could successfully attain green and red colors as well, thus realizing a full spectrum of visible colors. Additionally, we explored the multi-functional properties of photonic materials such as light-weight, water-repellency, tunable UV and IR reflectance, rendering them suitable for aerospace coatings, building thermoregulation and cosmetics. In summary, we have developed a novel approach of compatibilized polymer blend phase-separation to attain non-iridescent structural coloration from porous polymer resembling photonic structures in nature. This study provides insights into various aspects of phase-separation from a molecular perspective that impact coloration at macroscopic level. One of the key results of our study is that structural order in addition to correlation length determines non-iridescent structural coloration from quasi-ordered structures based on polymeric phase-separation. Furthermore, this is a robust and scalable method compatible via a roll-to-roll process that can be readily integrated on an industrial platform.
Alamgir Karim (Advisor)
Matthew Shawkey (Advisor)
Sadhan Jana (Committee Member)
Xiong Gong (Committee Chair)
Erol Sancaktar (Committee Member)
Tianbo Liu (Committee Member)
278 p.
Polymer Chemistry
Biomimetics; Non iridescence; Structural coloration; Polymer blends; Phase separation; Block copolymers; Compatibilization; Multi functional properties; Disordered and quasiordered structures; Coffee ring; Kinetics; Coatings; Cosmetics; Thermoregulation;

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Citations

  • Nallapaneni, A. (2020). BIOMIMETIC NON-IRIDESCENT STRUCTURAL COLORATION VIA PHASE-SEPARATION OF COMPATIBILIZED POLYMER BLEND FILMS [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1590749223865508

    APA Style (7th edition)

  • Nallapaneni, Asritha. BIOMIMETIC NON-IRIDESCENT STRUCTURAL COLORATION VIA PHASE-SEPARATION OF COMPATIBILIZED POLYMER BLEND FILMS. 2020. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1590749223865508.

    MLA Style (8th edition)

  • Nallapaneni, Asritha. "BIOMIMETIC NON-IRIDESCENT STRUCTURAL COLORATION VIA PHASE-SEPARATION OF COMPATIBILIZED POLYMER BLEND FILMS." Doctoral dissertation, University of Akron, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1590749223865508

    Chicago Manual of Style (17th edition)

akron1590749223865508
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This open access ETD is published by University of Akron and OhioLINK.