Optically Bistable Macroporous Photonic Crystals Enabled by Thermoresponsive Shape Memory Polymers

Fang, Yin; Leo, Sin‐Yen; Ni, Yongliang; Yu, Long; Qi, Pengxu; Wang, Bing-Chen; Basile, Vito; Taylor, Curtis R.; Jiang, Peng

doi:10.1002/adom.201500277

Cited by 50 publications

(37 citation statements)

References 69 publications

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“…Upon heating above the T g , the original shape and photonic structure recovers in approximately 200 s, resulting in a colourless to coloured transition. 34 A similar effect can be obtained using glassy cholesteric liquid crystal network (LCN) polymers. In cholesteric liquid crystals (CLCs) a periodic refractive index modulation is caused by the helical organization of the liquid crystals.…”

Section: One-way Temperature Responsive Photonic Polymersmentioning

confidence: 72%

Environmentally responsive photonic polymers

et al. 2019

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Section: One-way Temperature Responsive Photonic Polymersmentioning

confidence: 72%

Environmentally responsive photonic polymers

et al. 2019

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“…For example, colloidal crystals with narrow bandwidth and high transparency can be stacked to form multiple layers, which provide complex optical codes . In addition, colloidal crystals are further patterned to possess identification shapes . Such colloidal crystals delivering combinatorial codes of optical signals and graphical shapes can potentially serve as novel security materials for anti‐counterfeiting of banknotes and passports …”

Section: Introductionmentioning

confidence: 99%

Lithographically Encrypted Inverse Opals for Anti-Counterfeiting Applications

Heo

Kang

Lee

et al. 2016

Small

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Colloidal photonic crystals possess inimitable optical properties of iridescent structural colors and unique spectral shape, which render them useful for security materials. This work reports a novel method to encrypt graphical and spectral codes in polymeric inverse opals to provide advanced security. To accomplish this, this study prepares lithographically featured micropatterns on the top surface of hydrophobic inverse opals, which serve as shadow masks against the surface modification of air cavities to achieve hydrophilicity. The resultant inverse opals allow rapid infiltration of aqueous solution into the hydrophilic cavities while retaining air in the hydrophobic cavities. Therefore, the structural color of inverse opals is regioselectively red-shifted, disclosing the encrypted graphical codes. The decoded inverse opals also deliver unique reflectance spectral codes originated from two distinct regions. The combinatorial code composed of graphical and optical codes is revealed only when the aqueous solution agreed in advance is used for decoding. In addition, the encrypted inverse opals are chemically stable, providing invariant codes with high reproducibility. In addition, high mechanical stability enables the transfer of the films onto any surfaces. This novel encryption technology will provide a new opportunity in a wide range of security applications.

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“…For example, shape memory photonic films have been produced from core–interlayer–shell polymer microspheres that form opal structures . Alternatively porous inverse‐opal SMPs have been templated by silica colloids . Capillary pressure‐induced “cold” programming of these materials results in a disordered temporary state consisting of collapsed pores and an arbitrarily roughened surface, which can be recovered by pressure, heat, organic vapors, solvents, and microwave radiation .…”

Section: Introductionmentioning

confidence: 99%

Photonic Shape Memory Chiral Nematic Polymer Coatings with Changing Surface Topography and Color

Nickmans

Heijden

Schenning

2019

Advanced Optical Materials

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optical time-analyte indicators. [21,22] Regular surface topographies exhibiting structural colors have been fabricated in SMPs by top-down methods including locally induced surface wrinkling, [23] nanoimprint lithography, [24,25] compression molding, [26] or templating via microspheres. [27] In these examples, hot pressing of the surface features results in a temporary flattened and colorless state, which is reversible upon heating. [24][25][26][27] To circumvent the cumbersome topdown nanoforming steps to generate the structural color, photonic SMP coatings generated by bottom-up self-assembly have also been employed. [17,28,29] For example, shape memory photonic films have been produced from core-interlayer-shell polymer microspheres that form opal structures. [30][31][32] Alternatively porous inverse-opal SMPs have been templated by silica colloids. [33] Capillary pressure-induced "cold" programming of these materials results in a disordered temporary state consisting of collapsed pores and an arbitrarily roughened surface, which can be recovered by pressure, heat, organic vapors, solvents, and microwave radiation. [34][35][36][37][38][39] Unfortunately, the fabrication of such SMP coatings is still hampered by the lack of facile methods and materials. [40] Reactive liquid crystalline materials are exciting from this perspective since they form nanostructured phases via selfassembly, and can be easily processed via photopolymerization [41][42][43][44] to fabricate polymeric coatings. [45][46][47][48][49] Chiral nematic liquid crystalline (a.k.a. cholesteric liquid crystalline (CLC)) phases are of particular interest for their periodic helical structures which lead to the selective and incident-angledependent reflection of light, resulting in iridescent structural colors. [50] CLC coatings have been reported that respond to stimuli including heat, light, and humidity. [17,[51][52][53][54][55][56][57] In addition, CLC coatings have been reported that simultaneously change surface topography and color in a reversible manner. [41,55] Recently, our group reported that irreversible thermoresponsive photonic coatings can be fabricated based on CLC polymer networks using a shape memory approach. [58,59] Indentation of a small area (≈1 mm 2 ) of the CLC film, at a temperature above the T g of the polymer network, resulted in a blue-shift of the reflection band through a reduction of the pitch of the cholesteric helix, which was fully recovered upon heating.We now report a new approach for the fabrication of shape memory photonic coatings that irreversibly change both topography and color. Polymeric CLC films with a red structural The fabrication of shape memory coatings that change both reflectivity and topography is hampered by the lack of facile methods and materials. Now, shape memory photonic coatings are fabricated by high-speed flexographic printing and UV-curing in air of a chiral nematic liquid crystal ink. Deformable polymeric films with a red reflection band and a smooth surface topography are obtained which...

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Optically Bistable Macroporous Photonic Crystals Enabled by Thermoresponsive Shape Memory Polymers

Cited by 50 publications

References 69 publications

Environmentally responsive photonic polymers

Environmentally responsive photonic polymers

Lithographically Encrypted Inverse Opals for Anti-Counterfeiting Applications

Photonic Shape Memory Chiral Nematic Polymer Coatings with Changing Surface Topography and Color

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