Polymers for Chemosensing

A special issue of Polymers (ISSN 2073-4360).

Deadline for manuscript submissions: closed (28 February 2017) | Viewed by 105663

Special Issue Editor


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Guest Editor
Department of Chemical Engineering and Materials Science, Yuan Ze University, Taoyuan 32003, Taiwan
Interests: polymer modifications; radical polymerzation; self assembly; organic/inrganic composites; polymer coatings; biomedical applications
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Special Issue Information

Dear Colleagues,

This Special Issue of Polymers is dedicated to the synthesis and functionalization of polymers for chemosensing applications. In recent decades, the development of conjugated polymers has attracted increasing attention, due to their use as highly sensitive fluorescent chemosensors. Several applications have been demonstrated for sensing various analytes, measuring pH, and detecting metal ions and biological species in environmental applications by utilizing color and/or fluorescence intensities. Fluorescent chemosensors offer several crucial advantages over low-molecular-weight compounds. For instance, the chemical signals that are converted into electronic or optical signals when these conjugated polymers bind with an analyte can be transformed and enhanced effectively. During the formation of fluorescent ligand-metal ion complexes, intramolecular charge transfer (ICT) and coordination interactions cause the polymer backbone to undergo changes in electron charge distribution and molecular conformation. Additionally, the fluorophore of a conjugated polymer used as a fluorescent chemosensor is always bonded at the conjugated backbone, along which the excitons can diffuse easily, resulting in more marked and defined changes in the fluorescence intensity and bathochromic or hypsochromic shifts of the fluorescence wavelengths of these polymers.

This Special Issue covers the synthesis, characterization, functionalization, and chemosensory properties of polymers and hybrid organic-inorganic polymer composites. The aim of this Special Issue is to provide an update on recent research and knowledge in this field, and to broaden our perspectives on polymers used in chemosensing for environmental and medical applications.

Prof. Dr. Po-Chih Yang
Guest Editor

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Keywords

  • polymer synthesis
  • polymer composites
  • optical properties
  • fluorescent chemosensors
  • fluorescence enhancement/fluorescence quenching
  • charge transfer/electron transfer

Published Papers (14 papers)

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Research

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8088 KiB  
Article
Facile Synthesis of Polyaniline Nanotubes Using Self-Assembly Method Based on the Hydrogen Bonding: Mechanism and Application in Gas Sensing
by Changqing Yin, Lei Gao, Fei Zhou and Guotao Duan
Polymers 2017, 9(10), 544; https://doi.org/10.3390/polym9100544 - 24 Oct 2017
Cited by 25 | Viewed by 8198
Abstract
Based on hydrogen bonding, the highly uniform polyaniline (PANI) nanotubes were synthesized by self-assembly method using citric acid (CA) as the dopant and the structure-directing agent by optimizing the molar ratio of CA to aniline monomer (Ani). Synthesis conditions like reaction temperature and [...] Read more.
Based on hydrogen bonding, the highly uniform polyaniline (PANI) nanotubes were synthesized by self-assembly method using citric acid (CA) as the dopant and the structure-directing agent by optimizing the molar ratio of CA to aniline monomer (Ani). Synthesis conditions like reaction temperature and mechanical stirring were considered to explore the effects of hydrogen bonding on the morphologies. The effects of CA on the final morphology of the products were also investigated. The as-synthesized CA doped polyaniline (PANI) nanomaterials were further deposited on the plate electrodes for the test of gas sensing performance to ammonia (NH3). The sensitivity to various concentrations of NH3, the repeatability, and the stability of the sensors were also tested and analyzed. As a result, it was found that the PANI nanomaterial synthesized at the CA/Ani molar ratio of 0.5 has highly uniform tubular morphology and shows the best sensing performance to NH3. It makes the PANI nanotubes a promising material for high performance gas sensing to NH3. Full article
(This article belongs to the Special Issue Polymers for Chemosensing)
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5521 KiB  
Article
Synthesis, Chemosensory Properties, and Self-Assembly of Terpyridine-Containing Conjugated Polycarbazole through RAFT Polymerization and Heck Coupling Reaction
by Po-Chih Yang, Si-Qiao Li, Yueh-Han Chien, Ta-Lun Tao, Ruo-Yun Huang and Hsueh-Yu Chen
Polymers 2017, 9(9), 427; https://doi.org/10.3390/polym9090427 - 07 Sep 2017
Cited by 12 | Viewed by 8140
Abstract
We report the responsive fluorescence chemosensory phenomena of a carbazole-functionalized crosslinked polymer (PCaT) with pendent terpyridine (tpy) groups as receptors of metal ions. The polymer was synthesized using Heck polymerization between 3,6-dibromide groups in a carbazole-based polymer (PC2Br) and divinyl tpy monomer. The [...] Read more.
We report the responsive fluorescence chemosensory phenomena of a carbazole-functionalized crosslinked polymer (PCaT) with pendent terpyridine (tpy) groups as receptors of metal ions. The polymer was synthesized using Heck polymerization between 3,6-dibromide groups in a carbazole-based polymer (PC2Br) and divinyl tpy monomer. The effects of the polymeric structure on the optical and chemosensory properties of the PCaT were compared with those of a carbazole-tpy alternating conjugated polymer (PCT). Photoluminescence titrations demonstrated that the PCaT and PCT had the high sensing ability toward Fe3+ ions, with Stern–Volmer constants of 8.10 × 104 and 6.68 × 104 M−1, respectively. The limit of detection (LOD) toward Fe3+ of the PCaT and PCT was estimated to be 1.31 × 10−6 and 1.81 × 10−6 M, respectively, and the superior LOD of the PCaT was ascribed to its lowly crosslinked structure. The fluorescence of the solutions of these polymers that were quenched by Fe3+ ions recovered when trace CN anions were added because of the high stability constant of the CN–Fe3+ complex. Micellar aggregates with a mean diameter of approximately 239.5 nm were formed by dissolving the PCaT in tetrahydrofuran (THF) solution. Our results suggest that the PCaT is a promising material for chemosensory applications. Full article
(This article belongs to the Special Issue Polymers for Chemosensing)
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3119 KiB  
Article
A Conjugated Polyelectrolyte with Pendant High Dense Short-Alkyl-Chain-Bridged Cationic Ions: Analyte-Induced Light-Up and Label-Free Fluorescent Sensing of Tumor Markers
by Nina Fu, Yijiao Wang, Dan Liu, Caixia Zhang, Shao Su, Biqing Bao, Baomin Zhao and Lianhui Wang
Polymers 2017, 9(6), 227; https://doi.org/10.3390/polym9060227 - 15 Jun 2017
Cited by 5 | Viewed by 5216
Abstract
A novel cationic water-soluble conjugated polyelectrolyte (CPE) of polyfluorene that contains 15% fraction of 2,1,3-benzothiadiazole (BT) units (PFC3NBT) has been obtained. PFC3NBT demonstrates intramolecular energy transfer from the fluorene segments to BT sites when negatively charged species (SDS or DNAs) are added, following [...] Read more.
A novel cationic water-soluble conjugated polyelectrolyte (CPE) of polyfluorene that contains 15% fraction of 2,1,3-benzothiadiazole (BT) units (PFC3NBT) has been obtained. PFC3NBT demonstrates intramolecular energy transfer from the fluorene segments to BT sites when negatively charged species (SDS or DNAs) are added, following by a shift in emission color from blue to green, has been developed. The high density of positive charges and pendent short alkyl chains of N-propyltrimethylammoniums endow PFC3NBT with high solubility and high fluorescence quantum efficiency of 33.6% in water. The fluorescence emission properties were investigated in the presence of adverse buffer solutions, different surfactants and DNA strands. Interesting fluorescence emission quenching at short wavelength and fluorescence resonance energy transfer (FRET) induced light-on at BT sites were observed and discussed in detail. Very different from previous reports, the fluorescence emission spectra transition happens with an enhancement of integrated fluorescent intensity. The analytes induced a light-up sensing system was studied with a PFC3NBT/SDS complex mode and confirmed with DNA/DNA-FAM sensing systems. More exciting preliminary results on label-free sensing of tumor markers were also reported by investigating the unique fluorescence response to 11 kinds of proteins. These results provide a new insight view for designing CPEs with light-up and label-free features for biomolecular sensing. Full article
(This article belongs to the Special Issue Polymers for Chemosensing)
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6357 KiB  
Article
Novel Magnet and Thermoresponsive Chemosensory Electrospinning Fluorescent Nanofibers and Their Sensing Capability for Metal Ions
by Fang-Cheng Liang, Yi-Ling Luo, Chi-Ching Kuo, Bo-Yu Chen, Chia-Jung Cho, Fan-Jie Lin, Yang-Yen Yu and Redouane Borsali
Polymers 2017, 9(4), 136; https://doi.org/10.3390/polym9040136 - 10 Apr 2017
Cited by 24 | Viewed by 5982
Abstract
Novel multifunctional switchable chemosensors based on fluorescent electrospun (ES) nanofibers with sensitivity toward magnetism, temperature, and mercury ions (Hg2+) were prepared using blends of poly(N-isopropylacrylamide)-co-(N-methylolacrylamide)-co-(Acrylic acid), the fluorescent probe 1-benzoyl-3-[2-(2-allyl-1,3-dioxo-2,3-dihydro-1Hbenzo[de]isoquinolin-6-ylamino)-ethyl]-thiourea (BNPTU), and magnetite nanoparticles (NPs), and a single-capillary spinneret. The moieties [...] Read more.
Novel multifunctional switchable chemosensors based on fluorescent electrospun (ES) nanofibers with sensitivity toward magnetism, temperature, and mercury ions (Hg2+) were prepared using blends of poly(N-isopropylacrylamide)-co-(N-methylolacrylamide)-co-(Acrylic acid), the fluorescent probe 1-benzoyl-3-[2-(2-allyl-1,3-dioxo-2,3-dihydro-1Hbenzo[de]isoquinolin-6-ylamino)-ethyl]-thiourea (BNPTU), and magnetite nanoparticles (NPs), and a single-capillary spinneret. The moieties of N-isopropylacrylamide, N-methylolacrylamide, acrylic acid, BNPTU, and Iron oxide (Fe3O4) NPs were designed to provide thermoresponsiveness, chemical cross-linking, Fe3O4 NPs dispersion, Hg2+ sensing, and magnetism, respectively. The prepared nanofibers exhibited ultrasensitivity to Hg2+ (as low as 10−3 M) because of an 80-nm blueshift of the emission maximum (from green to blue) and 1.6-fold enhancement of the emission intensity, as well as substantial volume (or hydrophilic to hydrophobic) changes between 30 and 60 °C, attributed to the low critical solution temperature of the thermoresponsive N-isopropylacrylamide moiety. Such temperature-dependent variations in the presence of Hg2+ engendered distinct on–off switching of photoluminescence. The magnetic ES nanofibers can be collected using a magnet rather than being extracted through alternative methods. The results indicate that the prepared multifunctional fluorescent ES nanofibrous membranes can be used as naked eye sensors and have the potential for application in multifunctional environmental sensing devices for detecting metal ions, temperature, and magnetism as well as for water purification sensing filters. Full article
(This article belongs to the Special Issue Polymers for Chemosensing)
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6113 KiB  
Article
A Facile Approach for Fabrication of Core-Shell Magnetic Molecularly Imprinted Nanospheres towards Hypericin
by Wenxia Cheng, Fengfeng Fan, Ying Zhang, Zhichao Pei, Wenji Wang and Yuxin Pei
Polymers 2017, 9(4), 135; https://doi.org/10.3390/polym9040135 - 07 Apr 2017
Cited by 33 | Viewed by 7550
Abstract
By taking advantage of the self-polymerization of dopamine on the surface of magnetic nanospheres in weak alkaline Tris-HCl buffer solution, a facile approach was established to fabricate core-shell magnetic molecularly imprinted nanospheres towards hypericin (Fe3O4@PDA/Hyp NSs), via a surface [...] Read more.
By taking advantage of the self-polymerization of dopamine on the surface of magnetic nanospheres in weak alkaline Tris-HCl buffer solution, a facile approach was established to fabricate core-shell magnetic molecularly imprinted nanospheres towards hypericin (Fe3O4@PDA/Hyp NSs), via a surface molecular imprinting technique. The Fe3O4@PDA/Hyp NSs were characterized by FTIR, TEM, DLS, and BET methods, respectively. The reaction conditions for adsorption capacity and selectivity towards hypericin were optimized, and the Fe3O4@PDA/Hyp NSs synthesized under the optimized conditions showed a high adsorption capacity (Q = 18.28 mg/g) towards hypericin. The selectivity factors of Fe3O4@PDA/Hyp NSs were about 1.92 and 3.55 towards protohypericin and emodin, respectively. In addition, the approach established in this work showed good reproducibility for fabrication of Fe3O4@PDA/Hyp. Full article
(This article belongs to the Special Issue Polymers for Chemosensing)
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2862 KiB  
Communication
Label-Free Colorimetric Detection of Influenza Antigen Based on an Antibody-Polydiacetylene Conjugate and Its Coated Polyvinylidene Difluoride Membrane
by Jae-pil Jeong, Eunae Cho, Deokgyu Yun, Taejoon Kim, Im-Soon Lee and Seunho Jung
Polymers 2017, 9(4), 127; https://doi.org/10.3390/polym9040127 - 30 Mar 2017
Cited by 16 | Viewed by 7306
Abstract
This study presents an antibody-conjugated polydiacetylene (PDA) and its coated polyvinylidene difluoride (PVDF) membrane. The M149 antibody was hybridized to nano-vesicles consisting of pentacosa-10,12-diynoic acid (PCDA) and dimyristoylphosphatidylcholine (DMPC). After photo-polymerization at 254 nm, the effects on the PDA by antigenic injection were [...] Read more.
This study presents an antibody-conjugated polydiacetylene (PDA) and its coated polyvinylidene difluoride (PVDF) membrane. The M149 antibody was hybridized to nano-vesicles consisting of pentacosa-10,12-diynoic acid (PCDA) and dimyristoylphosphatidylcholine (DMPC). After photo-polymerization at 254 nm, the effects on the PDA by antigenic injection were investigated with UV-vis spectroscopy, fluorescence spectroscopy, dynamic light scattering and transmission electron microscopy. Because PDA, an alternating ene-yne molecule, induces a blue-to-red color transition and an interesting fluorescent response by the distortion of its backbone, the biomolecular recognition of an antibody–antigen can be converted into an optical and fluorescent signal. Thus, an influenza antigen was successfully detected with the proposed label-free method. Furthermore, the vesicular system was improved by coating it onto a membrane type sensing platform for its stability and portability. The proposed antibody-PDA composite PVDF membrane has potential for rapid, easy and selective visualization of the influenza virus. Full article
(This article belongs to the Special Issue Polymers for Chemosensing)
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2800 KiB  
Article
A Gelated Colloidal Crystal Attached Lens for Noninvasive Continuous Monitoring of Tear Glucose
by Jia-Li Ruan, Cheng Chen, Jian-Hua Shen, Xue-Ling Zhao, Shao-Hong Qian and Zhi-Gang Zhu
Polymers 2017, 9(4), 125; https://doi.org/10.3390/polym9040125 - 28 Mar 2017
Cited by 70 | Viewed by 11871
Abstract
Patients of diabetes mellitus urgently need noninvasive and continuous glucose monitoring in daily point-of-care. As the tear glucose concentration has a positive correlation with that in blood, the hydrogel colloidal crystal integrated into contact lens possesses promising potential for noninvasive monitoring of glucose [...] Read more.
Patients of diabetes mellitus urgently need noninvasive and continuous glucose monitoring in daily point-of-care. As the tear glucose concentration has a positive correlation with that in blood, the hydrogel colloidal crystal integrated into contact lens possesses promising potential for noninvasive monitoring of glucose in tears. This paper presents a new glucose-responsive sensor, which consists a crystalline colloidal array (CCA) embedded in hydrogel matrix, attached onto a rigid gas permeable (RGP) contact lens. This novel sensing lens is able to selectively diffract visible light, whose wavelength shifts between 567 and 468 nm according to the alternation of the glucose concentration between 0 and 50 mM and its visible color change between reddish yellow, green, and blue. The detection limit of responsive glucose concentration can be reduced to 0.05 mM. Its combination with a contact lens endows it with excellent biocompatibility and portability, which shows great possibility for it to push the development of glucose-detecting devices into new era. Full article
(This article belongs to the Special Issue Polymers for Chemosensing)
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2887 KiB  
Article
Pentiptycene-Derived Fluorescence Turn-Off Polymer Chemosensor for Copper(II) Cation with High Selectivity and Sensitivity
by Anting Chen, Wei Wu, Megan E. A. Fegley, Sherryllene S. Pinnock, Jetty L. Duffy-Matzner, William E. Bernier and Wayne E. Jones
Polymers 2017, 9(4), 118; https://doi.org/10.3390/polym9040118 - 24 Mar 2017
Cited by 8 | Viewed by 6226
Abstract
Fluorescent conjugated polymers (FCPs) have been explored for selective detection of metal cations with ultra-sensitivity in environmental and biological systems. Herein, a new FCP sensor, tmeda-PPpETE (poly[(pentiptycene ethynylene)-alt-(thienylene ethynylene)] with a N,N,N′-trimethylethylenediamino receptor), has been designed [...] Read more.
Fluorescent conjugated polymers (FCPs) have been explored for selective detection of metal cations with ultra-sensitivity in environmental and biological systems. Herein, a new FCP sensor, tmeda-PPpETE (poly[(pentiptycene ethynylene)-alt-(thienylene ethynylene)] with a N,N,N′-trimethylethylenediamino receptor), has been designed and synthesized via Sonogashira cross-coupling reaction with the goal of improving solid state polymer sensor development. The polymer was found to be emissive at λmax ~ 459 nm under UV radiation with a quantum yield of 0.119 at room temperature in THF solution. By incorporating diamino receptors and pentiptycene groups into the poly[(phenylene ethynylene)-(thiophene ethynylene)] (PPETE) backbone, the polymer showed an improved turn-off response towards copper(II) cation, with more than 99% quenching in fluorescence emission. It is capable of discriminating copper(II) cation from sixteen common cations, with a detection limit of 16.5 nM (1.04 ppb). Full article
(This article belongs to the Special Issue Polymers for Chemosensing)
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5204 KiB  
Article
Unusual Emission of Polystyrene-Based Alternating Copolymers Incorporating Aminobutyl Maleimide Fluorophore-Containing Polyhedral Oligomeric Silsesquioxane Nanoparticles
by Mohamed Gamal Mohamed, Yu-Ru Jheng, Shu-Ling Yeh, Tao Chen and Shiao-Wei Kuo
Polymers 2017, 9(3), 103; https://doi.org/10.3390/polym9030103 - 15 Mar 2017
Cited by 20 | Viewed by 7019
Abstract
In this study, we synthesized an unusual 2-aminobutyl maleimide isobutyl polyhedral oligomeric silsesquioxane (MIPOSS-NHBu) monomer lacking conventional fluorescent groups. We then prepared poly(styrene-alt-2-aminobutyl maleimide isobutyl POSS) [poly(S-alt-MIPOSS-NHBu)] and poly(4-acetoxystyrene-alt-2-aminobutyl maleimide isobutyl POSS) [poly(AS-alt-MIPOSS-NHBu)] copolymers through [...] Read more.
In this study, we synthesized an unusual 2-aminobutyl maleimide isobutyl polyhedral oligomeric silsesquioxane (MIPOSS-NHBu) monomer lacking conventional fluorescent groups. We then prepared poly(styrene-alt-2-aminobutyl maleimide isobutyl POSS) [poly(S-alt-MIPOSS-NHBu)] and poly(4-acetoxystyrene-alt-2-aminobutyl maleimide isobutyl POSS) [poly(AS-alt-MIPOSS-NHBu)] copolymers through facile free radical copolymerizations using azobisisobutyronitrile as the initiator and tetrahydrofuran as the solvent. A poly(4-hydroxystyrene-alt-2-aminobutyl maleimide isobutyl POSS) [poly(HS-alt-MIPOSS-NHBu)] copolymer was prepared through acetoxyl hydrazinolysis of poly(AS-alt-MIPOSS-NHBu). We employed 1H, 13C, and 29Si nuclear magnetic resonance spectroscopy; Fourier transform infrared spectroscopy; differential scanning calorimetry; and photoluminescence spectroscopy to investigate the structures and the thermal and optical properties of the monomers and novel POSS-containing alternating copolymers. Intramolecular hydrogen bonding between the amino and dihydrofuran-2,5-dione group and clustering of the locked C=O groups from the POSS nanoparticles in the MIPOSS-NHBu units restricted the intramolecular motion of the polymer chain, causing it to exhibit strong light emission. As a result, the MIPOSS-NHBu monomer and the poly(AS-alt-MIPOSS-NHBu) copolymer both have potential applicability in the detection of metal ions with good selectivity. Full article
(This article belongs to the Special Issue Polymers for Chemosensing)
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6957 KiB  
Article
Au Nanoparticles Immobilized on Honeycomb-Like Polymeric Films for Surface-Enhanced Raman Scattering (SERS) Detection
by Chia-Yen Chiang, Ting-Yu Liu, Yu-An Su, Chien-Hsin Wu, Yu-Wei Cheng, Ho-Wen Cheng and Ru-Jong Jeng
Polymers 2017, 9(3), 93; https://doi.org/10.3390/polym9030093 - 06 Mar 2017
Cited by 36 | Viewed by 9721
Abstract
We have successfully developed novel surface-enhanced Raman scattering (SERS) substrates with three-dimensional (3D) porous structures for effectively improving the sensitivity and reproducibility of SERS, which can rapidly detect small molecules (rhodamine 6G as an example). Periodical arrays of the honeycomb-like substrates were fabricated [...] Read more.
We have successfully developed novel surface-enhanced Raman scattering (SERS) substrates with three-dimensional (3D) porous structures for effectively improving the sensitivity and reproducibility of SERS, which can rapidly detect small molecules (rhodamine 6G as an example). Periodical arrays of the honeycomb-like substrates were fabricated by self-assembling polyurethane-co-azetidine-2,4-dione (PU-PAZ) polymers. PU-PAZ comprising amphiphilic dendrons could stabilize the phase separation between the water droplets and polymer solution, and then organize into regular porous structures during the breath figure method. Subsequently, SERS substrates were fabricated by immobilizing gold nanoparticles (AuNPs) onto the honeycomb-like films with various 3D porous structures, controlled by the different PU-PAZ concentrations and relative humidities. Results show that surface enhancement factors of honeycomb-like substrates were 20 times higher than that of flat-film substrates (control group) due to enormous hot-spots resonance effects by the 3D porous structure, verified through Raman mapping at various positions of the z-axis. Furthermore, the particle size effects were evaluated by immobilized 12 and 67 nm of AuNPs on the honeycomb-like substrates, indicating larger AuNPs could induce more pronounced hot-spots effects. The generation of hot-spots resonance to enhance Raman intensity is strongly dependent on the diameter of AuNPs and the pore size of the honeycomb-like and 3D porous substrates for label-free and rapid SERS detection. Full article
(This article belongs to the Special Issue Polymers for Chemosensing)
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1734 KiB  
Article
Potassium Iodide-Functionalized Polyaniline Nanothin Film Chemiresistor for Ultrasensitive Ozone Gas Sensing
by Sira Srinives, Tapan Sarkar, Raul Hernandez and Ashok Mulchandani
Polymers 2017, 9(3), 80; https://doi.org/10.3390/polym9030080 - 24 Feb 2017
Cited by 7 | Viewed by 4477
Abstract
Polyaniline (PANI) nanostructures have been widely studied for their sensitivity to atmospheric pollutants at ambient conditions. We recently showed an effective way to electropolymerize a PANI nanothin film on prefabricated microelectrodes, and demonstrated its remarkable sensing performance to be comparable to that of [...] Read more.
Polyaniline (PANI) nanostructures have been widely studied for their sensitivity to atmospheric pollutants at ambient conditions. We recently showed an effective way to electropolymerize a PANI nanothin film on prefabricated microelectrodes, and demonstrated its remarkable sensing performance to be comparable to that of a one-dimensional nanostructure, such as PANI nanowires. In this work, we report further progress in the application of the PANI nanothin film chemiresistive sensor for the detection of ozone (O3) by modifying the film with potassium iodide (KI). The KI-PANI sensor exhibited an excellent sensitivity to O3 (8–180 ppb O3 concentration rage) with a limit of detection of 230 ppt O3, and exquisite selectivity against active chemicals such as nitrogen dioxide (NO2) and sulfur dioxide (SO2). The sensing mechanism of the sensor relied on iodometric chemistry of KI and O3, producing triiodide ( I 3 ) that partially doped and increased electrical conductivity of the PANI film. The sensitivity and selectivity of the KI-functionalized PANI film demonstrates the potential use for KI-PANI-based O3 sensing devices in environmental monitoring and occupational safety. Full article
(This article belongs to the Special Issue Polymers for Chemosensing)
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5308 KiB  
Article
Real-Time Packing Behavior of Core-Shell Silica@Poly(N-isopropylacrylamide) Microspheres as Photonic Crystals for Visualizing in Thermal Sensing
by Karthikeyan Manivannan, Yi-Shen Huang, Bohr-Ran Huang, Chih-Feng Huang and Jem-Kun Chen
Polymers 2016, 8(12), 428; https://doi.org/10.3390/polym8120428 - 10 Dec 2016
Cited by 10 | Viewed by 6327
Abstract
We grafted thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) brushes from monodisperse SiO2 microspheres through surface-initiated atom transfer radical polymerization (SI ATRP) to generate core-shell structured SiO2@PNIPAM microspheres (SPMs). Regular-sized SPMs dispersed in aqueous solution and packed as photonic crystals (PCs) in [...] Read more.
We grafted thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) brushes from monodisperse SiO2 microspheres through surface-initiated atom transfer radical polymerization (SI ATRP) to generate core-shell structured SiO2@PNIPAM microspheres (SPMs). Regular-sized SPMs dispersed in aqueous solution and packed as photonic crystals (PCs) in dry state. Because of the microscale of the SPMs, the packing behavior of the PCs in water can be observed by optical microscopy. By increasing the temperature above the lower critical solution temperature (LCST) of PNIPAM, the reversible swelling and shrinking of the PNIPAM shell resulted in dispersion and precipitation (three-dimensional aggregation) of the SPM in aqueous solution. The SPMs were microdispersed in a water layer to accommodate the aggregation along two dimensions. In the microdispersion, the SPMs are packed as PCs with microscale spacing between SPMs below the LCST. When the temperature is increased above the LCST, the microdispersed PCs exhibited a close-packed arrangement along two dimensions with decreased spacing between SPMs. The change in spacing with increasing temperature above the LCST resulted in a color change from red to blue, which could be observed by the naked eye at an incident angle. Thus, the SPM array could be applied as a visual temperature sensor. Full article
(This article belongs to the Special Issue Polymers for Chemosensing)
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Review

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5328 KiB  
Review
Stimuli Responsive Polymer-Based 3D Optical Crystals for Sensing
by Qiang Zhang, Michael J. Serpe and Samuel M. Mugo
Polymers 2017, 9(11), 436; https://doi.org/10.3390/polym9110436 - 25 Oct 2017
Cited by 10 | Viewed by 6152
Abstract
3D optical crystals have found their applications in sensing, actuation, optical devices, batteries, supercapacitors, etc. The 3D optical crystal devices are comprised of two main components: colloidal gels and nanoparticles. Nanoparticles self-assemble into face center cubic structures in colloidal gels. The inherent 3D [...] Read more.
3D optical crystals have found their applications in sensing, actuation, optical devices, batteries, supercapacitors, etc. The 3D optical crystal devices are comprised of two main components: colloidal gels and nanoparticles. Nanoparticles self-assemble into face center cubic structures in colloidal gels. The inherent 3D optical crystal structure leads to display of structural colors on these devices following light impingement. As such, these optical properties have led to the utilization of these 3D optical crystals as self-reporting colorimetric sensors, which is the focus of this review paper. While there is extensive work done so far on these materials to exhaustively be covered in this review, we focus here in on: mechanism of color display, materials and preparation of 3D optical crystals, introduction of recent sensing examples, and combination of 3D optical crystals with molecular imprinting technology. The aim of this review is to familiarize the reader with recent developments in the area and to encourage further research in this field to overcome some of its challenges as well as to inspire creative innovations of these materials. Full article
(This article belongs to the Special Issue Polymers for Chemosensing)
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4896 KiB  
Review
Chemo-Electrical Gas Sensors Based on Conducting Polymer Hybrids
by Seon Joo Park, Chul Soon Park and Hyeonseok Yoon
Polymers 2017, 9(5), 155; https://doi.org/10.3390/polym9050155 - 26 Apr 2017
Cited by 145 | Viewed by 10569
Abstract
Conducting polymer (CP) hybrids, which combine CPs with heterogeneous species, have shown strong potential as electrical transducers in chemosensors. The charge transport properties of CPs are based on chemical redox reactions and provide various chemo-electrical signal transduction mechanisms. Combining CPs with other functional [...] Read more.
Conducting polymer (CP) hybrids, which combine CPs with heterogeneous species, have shown strong potential as electrical transducers in chemosensors. The charge transport properties of CPs are based on chemical redox reactions and provide various chemo-electrical signal transduction mechanisms. Combining CPs with other functional materials has provided opportunities to tailor their major morphological and physicochemical properties, often resulting in enhanced sensing performance. The hybrids can provide an enlarged effective surface area for enhanced interaction and chemical specificity to target analytes via a new signal transduction mechanism. Here, we review a selection of important CPs, including polyaniline, polypyrrole, polythiophene and their derivatives, to fabricate versatile organic and inorganic hybrid materials and their chemo-electrical sensing performance. We focus on what benefits can be achieved through material hybridization in the sensing application. Moreover, state-of-the-art trends in technologies of CP hybrid sensors are discussed, as are limitations and challenges. Full article
(This article belongs to the Special Issue Polymers for Chemosensing)
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