Inverse Opal Photonic Crystals Research Articles

Controllable Radical Polymerization of Selenide Functionalized Vinyl Monomers and Its Application in Redox Responsive Photonic Crystals

Selenium-containing monomer (p-phenylseleno) styrene (p-PhSeSt) is polymerized by reversible addition-fragmentation chain transfer polymerization. Polymer, (P(p-PhSeSt)), with controlled molecular weight and narrow molecular weight is obtained. The selenide moiety in obtained P(p-PhSeSt) can be selectively oxidized to selenoxide or selenone groups by H2 O2 or NaClO, respectively. These oxidized groups can be further reduced to selenide by Na2 S2 O4 . The structure changing of polymers during such redox cycle is characterized by nuclear magnetic resonance, X-ray photoelectron spectroscopy, and size exclusion chromatography. Properties, such as thermal performance, glass transition temperature, water contact angles, and refractive indices, of the resulting polymers are systematically investigated before and after oxidation. In addition, SiO2 inverse opal photonic crystal (IOPC) is fabricated by sacrificial polymer colloidal template method. Owing to changes of the RIs of P(p-PhSeSt) after selective oxidation, the predictable change of PC bandgap as a redox-responsive PC sensor is successfully realized, which provides new perspectives for modulating photonic crystals.

Slow Photon-induced Enhancement of Photocatalytic Activity of Gold Nanoparticle-incorporated Titania Inverse Opal

Abstract Here, we report a novel structured material, titania inverse-opal photonic crystal with or without a single gold nanoparticle in each void, to provide a photoabsorption design strategy as enhanced photoreaction rates, only when wavelengths of photoirradiation, photoabsorption (by gold nanoparticles or titania), and photonic-bandgap edge are trebly matched.

Detection of amine gases by inverse opal photonic crystals infiltrated with precursor HPQ‐Ac of aggregation‐induced emission luminogen

AbstractIn this study, to detect amine gases such as ammonia, a kind of biological gas, with high sensitivity, we fabricated a device that combines an inverse opal photonic crystal (IOPC) and 2‐(4‐oxo‐3,4‐dihydroquinazolin‐2‐yl)phenyl acetate (HPQ‐Ac), a precursor of the aggregation‐induced emission luminogen. IOPC silica structures (200IOPC, 350IOPC, 500IOPC) with SiO2 were respectively obtained after calcination with 200, 350, and 500 nm polystyrene (PS) nanoparticles used as templates and tetraethyl orthosilicate (TEOS) formed by self‐assembly on a slide glass. Furthermore, mesopore‐introduced IOPC (50 nm‐350IOPC) was prepared by mixing 350 and 50 nm PS particles in TEOS solution. Each IOPC was infiltrated with HPQ‐Ac, reacted with ammonia, and the rate of change in emission intensity owing to fluorescence was examined. The highest response was obtained for 350IOPC infiltrated with HPQ‐Ac among the three IOPCs without mesopores. The 50 nm‐350IOPC had higher sensitivity than 350IOPC and was found to be able to detect 50 ppb ammonia gas.

An ordered fish scale-like Co-TiO2/GO inverse opal photonic crystal as the multifunctional SERS substrate

Nowadays, developing highly sensitive and multifunctional surface-enhanced Raman scattering (SERS) substrates is very significant. Here, a new cobalt (Co)-doped titanium dioxide (TiO2)/graphene oxide (GO) inverse opal photonic crystal (IO PC) was successfully synthesized using polystyrene opal as the template. The scanning and transmission electron microscope images demonstrate the ordered fish scale-like shape while the element mappings display the uniform element distribution of the Co-TiO2/GO IO PC. Raman spectra show that the detection limit of 4-mercaptobenzoic acid (4-MBA) on the Co-TiO2/GO IO PC SERS substrate is as low as 10−12 M, exhibiting better SERS effect than TiO2 and Co-TiO2 IO PCs. Amperometric I-t curves reveal that the photocurrent density of Co-TiO2/GO IO PC is six and three times more than that of TiO2 and Co-TiO2 IO PCs under simulated sunlight irradiation, respectively. Furthermore, UV-Vis spectra indicate that the degradation rate of methylene blue and Congo red over Co-TiO2/GO IO PC photocatalyst could separately reach 96% and 93%, which are much higher than that over TiO2 and Co-TiO2 IO PCs. The outstanding performance of Co-TiO2/GO IO PC was caused by that the Co2+ doping and GO addition broadened the light absorption to visible range, the electron traps resulted from Co2+ doping inhibited the recombination of electron-hole pairs and doping levels promoted TiO2-to-molecule charge-transfer process, which were confirmed by the UV-Vis spectra, PL spectra and SERS spectra, respectively. At the same time the periodic IO PC structure led to multiple scattering of light and improved the light-mass interaction. The prepared Co-TiO2/GO IO PC may be a promising material in SERS effect, water purification and so on.

Titania Inverse-Opal Photonic Crystals Incorporating Gold Nanoparticles in Void Spaces for Photoabsorption Enhancement

Designing of three-dimensional (3D) materials such as inverse-opal (IO) photonic crystals (PCs) has been identified as an effective pathway to enhance light harvesting to longer electromagnetic absorption regions such as visible and infrared [1]. IO PCs exhibit photonic band gap (PBG) and this band structure predicts the translation of photons with reduced velocity, namely as slow photons at certain crystallographic directions. The photonic effect from titania (TiO2)-IO structure was reported to enhance light-material interactions thus allowing better absorption of light at the wavelength at which the materials absorb poorly [2]. On the other hand, utilization of gold-nanoparticles (Au-NPs) on TiO2 could aid in charge separation and play its role as an amplifier for visible-light absorption due to its effects originating from localized surface plasmon resonance (LSPR) [3]. In this study, TiO2-IO PC with incorporated gold nanoparticles (Au-NPs) per void space was developed by implementing five important steps to achieve a good quality of TiO2-IO structure. Both photonic effects due to the slow photons in TiO2-IO structure and LSPR effects contributed by Au-NPs were expected to give visible-light absorption by the photocatalyst material.The experimental procedure consists of five steps as shown in Scheme 1 starting from (i) synthesis of Au-NPs, (ii) silica (SiO2) coating on Au-NP to form Au/SiO2 core-shells, (iii) self-assembly of Au/SiO2 to form high-quality opal structure, (iv) infiltration of TiO2 precursor via forced impregnation method and (v) selective etching of SiO2 to obtain the final TiO2-IO structure. Photodegradation of acetic acid was carried out in the presence of the photocatalyst material by using blue LED light (450 nm) with optical power of 0.3 W. SiO2 containing Au-NP (Au/SiO2) was used as the opal template for the 3D macroporous TiO2-IO containing Au-NP per void space (TiO2(Au)-IO). Figures 1a and 1b are images observed for Au/SiO2 opal structure exhibiting face-centered cubic (FCC) arrangement. As is observed, the closely packed opal structure could be obtained as the minimum variation among each particle was less than 5 %. However, extra precautions should be taken to avoid cracking on the opal structure to sustain the quality of the final desired material. Figures 1c and 1d are images of TiO2(Au)-IO which was successfully obtained after TiO2 infiltration via forced impregnation method followed by the removal of SiO2 to form the nanovoids. The strategy that has been implemented to enhance the light harvesting process was by designing the TiO2-IO structure with different diameter of nanovoids, which can be controlled by altering the SiO2 shell thickness in the second step of the synthesis process.Photocatalytic activities of those samples were evaluated by measuring the amount of carbon-dioxide (CO2) generated from acetic acid by TiO2(Au)-IO with different diameter of nanovoid diameters (Au-NP size: 44 nm) under LED light irradiation (4 h). Enhanced CO2 evolution was detected with TiO2(Au)-IO with nanovoid diameter of 215 nm suggesting the successful matching of photonic and LSPR effects in TiO2(Au)-IO.[1] X. Zheng, D. Li, X. Li, L. Yu, P. Wang, X. Zhang, J. Fang, Yu. Shao and Y. Zheng. Phys. Chem. Chem. Phys. 16 (2014) 15299–15306.[2] V. Jovic, H. Idriss and G.I.N. Waterhouse. Chem. Phys. 479 (2016) 109–121.[3] S.M. Yoo, S.B. Rawal, J.E. Lee, J. Kim, H. Ryu, D. Park and W.E. Lee. Appl. Catal. A Gen. 499 (2015) 47–54. Figure 1

Detection of Amine Gases by Inverse Opal Photonic Crystals Infiltrated with Precursor HPQ-Ac of Aggregation-Induced Emission Luminogen

Detection of Amine Gases by Inverse Opal Photonic Crystals Infiltrated with Precursor HPQ-Ac of Aggregation-Induced Emission Luminogen

Signal amplified sandwich-type photoelectrochemical sensing assay based on rGO-Znln2S4 functionalized Au–WO3 IOPCs Z-scheme heterojunction

A novel photoelectrochemical (PEC) detection strategy based on reduced graphene oxide-Znln2S4 (rGO-Znln2S4) functionalized Au–WO3 inverse opal photonic crystals (IOPCs) Z-scheme photoresponse system was designed. Benefiting from great optical property of WO3 IOPCs, the optical absorption of PEC sensor was highly enhanced. Meanwhile, the ‘Z-scheme’ electron transfer between Znln2S4 and WO3 IOPCs with application of Au nanoparticles (NPs) and rGO as electron mediators largely promoted separation of photo-generated carriers. Consequently, the enhanced optical absorption and accelerated photo-excited charge separation were beneficial to increase of photocurrent, resulting in an amplification of detection signal. The sandwich-type analytical mode was further applied to enhance the specificity and increase the sensitivity. Under optimum conditions, the PEC sensing system exhibited great property towards oxytetracycline (OTC) detection with a linear range of 2 × 10−4 −1 × 10−1 nM and a low detection limit of 1.2 × 10−4 nM (≈ 5.52 × 10−2 ng L−1). Given these advantages, the developed PEC sensing strategy offers a new avenue for efficient detection of other targets.

Intelligent Silk Fibroin Based Microneedle Dressing (i‐SMD)

AbstractWounds, especially those caused by chronic diseases, are severe threats to human health. To facilitate their recovery, considerable efforts have been devoted to the generation of wound tissues and the detection of wound biomarkers. Here, an intelligent origami silk fibroin microneedle‐structured dressing (i‐SMD) with a smart drug release system, biochemical sensing, and physiological monitoring ability for epidermal sensing and wound healing, is presented. By utilizing temperature‐responsive N‐isopropylacrylamide (NIPAM) hydrogel and inverse opal (IO) photonic crystals (PCs) as a smart drug release system, controllable drug release is achieved on the i‐SMD. The patterned microfluidic channels on the i‐SMD and IO PCs enable the liquid to flow spontaneously in the channels, thereby achieving sensitive multiple biochemical analysis of inflammatory factors; meanwhile, microelectronic circuits integrated on the i‐SMD enable sensitive motion monitoring. Notably, the performance of i‐SMD in facilitating wound healing is demonstrated by treating full‐thickness cutaneous wounds in a diabetic mouse model, indicating the remarkable prospects of i‐SMD in wound management and other related biomedical fields.

Studies on the active radicals in synthesized inverse opal photonic crystal and its effect on photocatalytic removal of organic pollutants

Ternary inverse opal TiO2-ZrTiO4-SiO2 photonic crystal (IOPC-TZS) photocatalysts have been synthesized in-situ by a simple template method. The morphology and thickness of the inverse opal photocatalysts with photonic crystal structure were controlled and optimized in order to obtain the inverse opal structure while maintaining the crystalline phase. The photocatalytic performance among the IOPC-TZS photocatalysts of Rhodamine B removal is 27 times higher than P25, and the excellent catalytic stability is observed even after three testing cycles. Compared with previous TiO2-ZrTiO4-SiO2 (TZS) powders, the OH radicals that appear in inverse opal photonic crystal structure play an important role in the RhB degradation due to the up-shifted band structure. The formation of the TiO2-ZrTiO4 heterojunction, the slow-photon-effect and the existence of the oxygen vacancies caused by the high active surface among the IOPC structure, result in the synergistic effect of remarkably enhanced separation efficiency and improved redox capacity of the photo-induced charge carriers, which boost the photodegradation behavior to organic pollutants.

How Light Passes Through Ordered Macroporous Photonic Crystals Immersed in Solvents

A better understanding of light transmission and relation to photonic bandgap in inverse opal photonic crystals is important when these structures are examined in liquids or solvents. We present a study of light tranmission through TiO2 and SnO2 inverse opals in several common solvents. The data and analysis identifies a correction to the Bragg-Snell theory and the photonic crystal unit cell definition that consolidates some inconsistencies between Bragg-Snell theory in various index solvents and physical measurements of inverse opals. We show experimental studies that suggest low fill factors in inverse opals are defined by porous material infilling all interstitial vacancies in the opal template to form an IO.

Ordered Macroporous Photonic Crystal Hot Electron Plasmonic Photocatalysts

Plasmonic metal-semiconductor heterostructures are promising for photocatalytic applications since the metal and the oxide semiconductor can absorb light in the visible spectrum leading to better catalytic rates. Photon absorption efficiency can be enhanced by fashioning the catalyst into a photonic crystal that can enhance absorption at certain wavelength because of its structure. We show how Au nanoparticle sensitized V2O5 and TiO2 inverse opal photonic crystals can enhanced reaction rate for catalysis by over an order of magnitude under λ = 532 nm excitation or under white light illumination. This effect is shown to results from spectral overlap of the electronic band gap, localized surface plasmon resonance and the excitation photon energy. When we compare the photocatalytic response of Au-V2O5 IO with Au-TiO2 IO, we can selectively enhance reaction rates either in the visible or in the UV regions, depending on the bandgap of the semiconductor, and the photonic band gap of the IO. For Au-TiO2 IO, hot electron transfer occurs from the gold into the conduction band, and better catalysis under white light illumination at the TiO2 surface is attributed to improved photon adsorption in the visible by the presence of a photonic band gap, slow light in the photonic crystal to enhance photon absorption, the UV bandgap of the TiO2, and the localised surface plasmon resonance of the Au. For Au-V2O5, electron transfer to the Au in addition to enhanced absorption in the visible range, promote better catalysis at λ = 532 nm.

Structurally colored silica photonic crystal coatings modified by Ce or Eu rare-earth dopants

Recently three-dimensional photonic crystal (PC) materials with inverse opal morphology are very popular due to their high application capacity. The structural color that is one of these popular application areas attracts attention with fadeless bright color, low toxicity and eco-friendly features. With this respect, silica based inverse opal photonic crystals were deposited on borosilicate glass substrates and the effect of the cerium (Ce) and europium (Eu) dopants on the properties of these coatings were investigated in detail. Thermal, structural and physical properties were characterized via differential thermal analysis (DTA-TGA), x-ray photoelectron spectroscopy (XPS), x-ray diffractometer (XRD), scanning electron microscope (SEM), UV spectrophotometer (UV–vis) and optical microscope (OM), respectively. The results reveal that the ordered porous honeycomb like morphology surrounds the entire 3-D structure. Periodically ordered photonic crystal morphologies are achieved at the coatings with the lowest dopant ratios. SiO2 based PC coatings possess blue and purple structural colors. It was found that the photonic band gap value was red-shifted by Ce doping in the coating while blue-shifting by Eu doping.

Filling in the gaps: The nature of light transmission through solvent-filled inverse opal photonic crystals

Understanding the nature of light transmission and the photonic bandgap in inverse opal photonic crystals is essential for linking their optical characteristics to any application. This is especially important when these structures are examined in liquids or solvents. We examined TiO2 and SnO2 IOs in a range of common solvents to solve the conflict between Bragg-Snell theory, optical and physical measurements by a comprehensive angle-resolved light transmission study coupled to microscopy examination of the IO structure. Tuning the position of the photonic bandgap and index contrast by solvent infiltration of each inverse opal requires a modification to the Bragg-Snell theory and the photonic crystal unit cell definition. We also demonstrate experimentally and theroetically that low fill factors are caused by less desne material infilling all interstitial vancancies in the opal template to form an IO. By also including an optical interference condition for inverse opals with an effective refractive index greater than its substrate, and an alternative internal refraction angle in the substrate, angle-resolved transmission spectra for inverse opals are now consistent with physical measurements. This work now allows an accurate correlation between the true response of an IO to the index contrast with a solvent, how an IO is infilled, and the directionality and bandwidth of the photonic bandgap. As control in functional photonic materials becomes more prevalent outside of optics and photonics, such as biosensing and energy storage, for example, a comprehensive and consistent correlation between photonic crystals structures and their primary optical signatures is a fundamental requirement for application.

Dimethyl sulfoxide infiltrated photonic crystals for gas sensing

Colorimetric sensors were fabricated by embedding three dimensional (3D) inverse opal photonic crystal (IOPC) structure inside a dimethyl sulfoxide (DMSO) infiltrated carboxymethyl cellulose membrane for gas sensing. The DMSO infiltrated IOPC (DMSO-IOPC) carboxymethyl cellulose sensors can perform visual, on-site monitoring for analytes including alcohols, acetone and hydrogen peroxide (H2O2). After exposed to alcohols and acetone, the mean effective refractive index (RI) and lattice constant of DMSO-IOPCs were changed, which led to a redshift of diffraction peak of the incident light. Sequentially their structural color changed remarkably. The limit of detection (LOD) for methanol and ethanol vapors are 110 ppm and 102 ppm, respectively. The H2O2 sensor is also achieved by using DMSO-IOPCs, and the diffraction blue-shifted when they were exposed to H2O2 vapor. In addition, this DMSO-IOPC sensor shows excellent selectivity and reversibility. The sensing mechanism of the DMSO-IOPC membranes was explained and simulated using finite-different time-domain (FDTD) method, and the experimental results were consistent with the simulated results. The DMSO-IOPCs demonstrate promising potential for in-situ monitoring of alcohol vapors, and could be used for peroxides detection and as a cheap and minimally invasive breathalyzer.

Design of a ZnO/Poly(vinylidene fluoride) inverse opal film for photon localization-assisted full solar spectrum photocatalysis

Owing to its photonic band gap (PBG) and slow light effects, aniline black (AB)-poly(vinylidene fluoride) (PVDF) inverse opal (IO) photonic crystal (PC) was constructed to promote the utility of light and realize photothermal synergetic catalysis. As a highly efficient reaction platform with the capability of restricting heat, a microreactor was introduced to further amplify the photothermal effects of near infrared (NIR) radiation. The photocatalytic efficiency of ZnO/0.5AB-PVDF IO (Z0.5A) increases 1.63-fold compared to that of pure ZnO film under a full solar spectrum, indicating the effectiveness of synergetic promotion by slow light and photothermal effects. Moreover, a 5.85-fold increase is achieved by combining Z0.5A with a microreactor compared to the film in a beaker. The photon localization effect of PVDF IO was further exemplified by finite-difference time-domain (FDTD) calculations. In conclusion, photonic crystal-microreactor enhanced photothermal catalysis has immense potential for alleviating the deteriorating water environment.

(Invited) Titania Inverse-Opal Photonic Crystals Incorporating Gold Nanoparticles in Void Spaces for Photoabsorption Enhancement

Designing of three-dimensional (3D) materials such as inverse-opal (IO) photonic crystals (PCs) has been identified as an effective pathway to enhance light harvesting to longer electromagnetic absorption regions such as visible and infrared [1]. IO PCs exhibit photonic band gap (PBG) and this band structure predicts the translation of photons with reduced velocity, namely as slow photons at certain crystallographic directions. The photonic effect from titania (TiO2)-IO structure was reported to enhance light-material interactions thus allowing better absorption of light at the wavelength at which the materials absorb poorly [2]. On the other hand, utilization of gold-nanoparticles (Au-NPs) on TiO2 could aid in charge separation and play its role as an amplifier for visible-light absorption due to its effects originating from localized surface plasmon resonance (LSPR) [3]. In this study, TiO2-IO PC with incorporated gold nanoparticles (Au-NPs) per void space was developed by implementing five important steps to achieve a good quality of TiO2-IO structure. Both photonic effects due to the slow photons in TiO2-IO structure and LSPR effects contributed by Au-NPs were expected to give visible-light absorption by the photocatalyst materialThe experimental procedure consists of five steps as shown in Scheme 1 starting from (i) synthesis of Au-NPs, (ii) silica (SiO2) coating on Au-NP to form Au/SiO2 core-shells, (iii) self-assembly of Au/SiO2 to form high-quality opal structure, (iv) infiltration of TiO2 precursor via forced impregnation method and (v) selective etching of SiO2 to obtain the final TiO2-IO structure. Photodegradation of acetic acid was carried out in the presence of the photocatalyst material by using blue LED light (450 nm) with optical power of 0.3 W.SiO2 containing Au-NP (Au/SiO2) was used as the opal template for the 3D macroporous TiO2-IO containing Au-NP per void space (TiO2(Au)-IO). Figures 1a and 1b are images observed for Au/SiO2 opal structure exhibiting face-centered cubic (FCC) arrangement. As is observed, the closely packed opal structure could be obtained as the minimum variation among each particle was less than 5 %. However, extra precautions should be taken to avoid cracking on the opal structure to sustain the quality of the final desired material. Figures 1c and 1d are images of TiO2(Au)-IO which was successfully obtained after TiO2 infiltration via forced impregnation method followed by the removal of SiO2 to form the nanovoids. The strategy that has been implemented to enhance the light harvesting process was by designing the TiO2-IO structure with different diameter of nanovoids, which can be controlled by altering the SiO2 shell thickness in the second step of the synthesis process.Photocatalytic activities of those samples were evaluated by measuring the amount of carbon-dioxide (CO2) generated from acetic acid by TiO2(Au)-IO with different diameter of nanovoid diameters (Au-NP size: 44 nm) under LED light irradiation (4 h). Enhanced CO2 evolution was detected with TiO2(Au)-IO with nanovoid diameter of 215 nm suggesting the successful matching of photonic and LSPR effects in TiO2(Au)-IO.

Colloidal Self-Assembly of Highly-Ordered Silica Inverse Opals for Deep Ultraviolet Diffraction

The fabrication of highly-ordered ~2 µm thick silica inverse opal (IO) photonic crystal (PhC) films is reported. These IO films diffract deep ultraviolet light (UV, < 250 nm) and are prepared using...

Semiconducting Metal Oxide Photonic Crystal Plasmonic Photocatalysts

AbstractPlasmonic photocatalysis has facilitated rapid progress in enhancing photocatalytic efficiency under visible light irradiation. Poor visible‐light‐responsive photocatalytic materials and low photocatalytic efficiency remain major challenges. Plasmonic metal–semiconductor heterostructures where both the metal and semiconductor are photosensitive are promising for light harvesting catalysis, as both components can absorb solar light. Efficiency of photon capture can be further improved by structuring the catalyst as a photonic crystal. Here, the synthesis of photonic crystal plasmonic photocatalyst materials using Au nanoparticle‐functionalized inverse opal (IO) photonic crystals is reported. A catalyst prepared using a visible‐light‐responsive semiconductor (V2O5) displayed over an order of magnitude increase in reaction rate under green light excitation (λ = 532 nm) compared to no illumination. The superior performance of Au‐V2O5 IO is attributed to spectral overlap of the electronic bandgap, localized surface plasmon resonance, and incident light source. For the Au‐TiO2 catalyst, despite coupling of the LSPR and excitation source at λ = 532 nm, this is not as effective in enhancing photocatalytic activity compared to carrying out the reaction under broadband visible light, which is attributed to improved photon adsorption in the visible by the presence of a photonic bandgap, and exploiting slow light in the photonic crystal to enhance photon absorption to create this synergistic type of photocatalyst.

Signal amplified photoelectrochemical assay based on Polypyrrole/g-C3N4/WO3 inverse opal photonic crystals triple heterojunction assembled through sandwich-type recognition model

A novel photoelectrochemical (PEC) sensing strategy with an amplified signal was proposed based on polypyrrole/g-C3N4/WO3 inverse opal photonic crystals triple heterojunction. The sandwich-type detection model was applied to increase the sensitivity and favor the assembly of heterojunction structure. The heterojunction among PPy, g-C3N4 and WO3 highly improved the separation of photo-generated charges. Meanwhile, WO3 IOPCs with good optical performance were employed to enhance the light absorption of PEC detection electrode. With the simultaneous combination of these amplification techniques, the designed PEC sensor achieved high sensitivity with low limit of detection (LOD) as 0.004 nM (≈ 1.99 ng L−1) and admirable selectivity in the detection of oxytetracycline under visible light irradiation.

Selective and Colorimetric Detection of p-Nitrophenol Based on Inverse Opal Polymeric Photonic Crystals.

The detection of p-nitrophenol (PNP) is of great significance for assessment of environment pollution and potential health risks. In this study, based on inverse opal polymeric photonic crystals (IOPPCs), a selective and visual sensor for high-performance PNP detection is developed. Due to their unique optical properties, IOPPCs report events by change of color, which can easily be observed by the naked eye. Hydroxyethyl methacrylate (HEMA) was selected as the functional monomer with which to fabricate the IOPPCs. By precisely adjusting the molar ratio between the functional monomer and the crosslinker, the sensors were only able to be sensitive to a specific solution, thus realizing the visual, selective, and semi-quantitative detection of PNP. When the sensors were immersed in different concentrations of PNP solution, their Bragg diffraction wavelengths showed different redshifts. The color of the IOPPCs changed from green to red as the peak shift of Bragg diffraction occurred. In addition, the IOPPCs displayed good interference immunity and reusability.