Special Issue "Polymeric Materials for Optical Applications"

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

Deadline for manuscript submissions: closed (26 January 2018).

Special Issue Editors

Prof. Dr. José Paulo Farinha
E-Mail Website
Guest Editor
Department of Chemical Engineering, Instituto Superior Técnico, University of Lisbon
Interests: functinal nanomaterials; nanoparticles; polymers and colloids; emulsion and miniemulsion polymerization; controled radical polymerization (RAFT); polymer coatings; optical sensor nanomaterials; fluorescence applications and laser scanning microscopy
Dr. Carlos Baleizão
E-Mail Website
Guest Editor
Department of Chemical Engineering, Instituto Superior Técnico, University of Lisbon
Interests: hybrid nanomaterials; nanoparticles; nanostructures for energy applications; controled radical polymerization; optical fluorescence sensors; fluorescent dyes

Special Issue Information

Dear Colleagues,

This Special Issue focus on the current state-of-the-art of polymeric materials for optical applications. The use of polymeric materials in optical applications is widespread, ranging from conjugated polymers for photovoltaics and optical (LED) devices, to optical sensing, bioimaging with dye-labelled polymers, nonlinear optics, light harvesting, different optical components and materials for structural color.

Papers are sought that discuss the latest research in the area or summarize selected areas of the field. The scope of the Special Issue encompasses the synthesis and characterization of polymers used for optical applications, including polymer chains, gels, polymer nanoparticles, polymer based nanocomposites and hybrid assemblies.

Of particular interests are new structures and functions resulting from the synthesis and processing of polymer materials featuring specific interactions with light, and new insights on the structure-optical properties relationships leading to enhanced functionality.

Prof. Dr. José Paulo Farinha
Dr. Carlos Baleizão
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Conjugated polymers for energy applications

  • Polymers for optical sensing

  • Dye labeled polymers for bioimaging

  • Polymers for nonlinear optics

  • Polymers for light harvesting

  • Polymer materials for structural color

  • Polymers for optical components

Published Papers (25 papers)

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Research

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Open AccessArticle
Optical Waveguide Tunable Phase Delay Lines Based on the Superior Thermo-Optic Effect of Polymer
Polymers 2018, 10(5), 497; https://doi.org/10.3390/polym10050497 - 04 May 2018
Cited by 1
Abstract
Strong thermo-optic effect of polymers is useful for fabricating tunable phase-delay devices with low power consumption and wide tuning range. However, if the temperature change is increased to extend the tuning range, an attenuation of the guided light is accompanied by the refractive [...] Read more.
Strong thermo-optic effect of polymers is useful for fabricating tunable phase-delay devices with low power consumption and wide tuning range. However, if the temperature change is increased to extend the tuning range, an attenuation of the guided light is accompanied by the refractive index gradient across the waveguide core. For three different waveguide structures, in this study, the optimal structure of the device for a variable phase delay line was found by investigating the attenuation and interference phenomena accompanying phase modulation. By improving the uniformity of thermal distribution across the waveguide core, a phase delay of 130π rad was obtained with an output attenuation less than 0.5 dB. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Thermal Dependence of Optical Parameters of Thin Polythiophene Films Blended with PCBM
Polymers 2018, 10(4), 454; https://doi.org/10.3390/polym10040454 - 19 Apr 2018
Abstract
The main purpose of this work is to show the thermal dependence of the refractive and extinction indices of conjugated polymer films used in optoelectronics devices. Herein, we present the results of optical investigations performed for the following polymers: poly(3-hexylthiophene) (P3HT), poly(3-octylthiophene) (P3OT), [...] Read more.
The main purpose of this work is to show the thermal dependence of the refractive and extinction indices of conjugated polymer films used in optoelectronics devices. Herein, we present the results of optical investigations performed for the following polymers: poly(3-hexylthiophene) (P3HT), poly(3-octylthiophene) (P3OT), and their blends with [6,6]-phenyl C61 butyric acid methyl ester (PCBM). For our analysis, we chose well-known polythiophenes such P3HT and P3OT, often used in photovoltaic cells. Our addition of PCMB to the polythiophenes allows their conversion efficiency to be increased. This paper presents the results of our investigation determining the spectral dispersion of optical constants in a wavelength range of 190–1700 nm by using spectroscopic ellipsometry (SE). Furthermore, we show the temperature dependence of the refractive indices of polythiophene films for a heating and a cooling process in the temperature range 25–130 °C. Additionally, thermo-optic coefficients and an optical gap were established and are presented in the paper, followed by a discussion on the conditions of the thermal stability of polythiophene blends and reversibility issues in thermal processes. Our paper presents a new and fresh analysis of depolarization beams after their reflection from the studied films. The paper presents the results of thermo-optical studies of polymer blends which have not been included in previously published works. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Highly Efficient Luminescent Polycarboxylate Lanthanide Complexes Incorporated into Di-Ureasils by an In-Situ Sol—Gel Process
Polymers 2018, 10(4), 434; https://doi.org/10.3390/polym10040434 - 13 Apr 2018
Cited by 1
Abstract
In order to prepare efficient luminescent organic–inorganic hybrid materials embedded with a lanthanide (Ln3+) complex with polycarboxylate ligands, Ln3+-doped di-ureasils with 4,4-oxybis(benzoic acid) and 1,10-phenanthroline ligands were synthesized via an in-situ sol–gel route. The resulting hybrids were structurally, thermally, [...] Read more.
In order to prepare efficient luminescent organic–inorganic hybrid materials embedded with a lanthanide (Ln3+) complex with polycarboxylate ligands, Ln3+-doped di-ureasils with 4,4-oxybis(benzoic acid) and 1,10-phenanthroline ligands were synthesized via an in-situ sol–gel route. The resulting hybrids were structurally, thermally, and optically characterized. The energy levels of the ligands and the host-to-ion and ligand-to-ion energy transfer mechanisms were investigated (including DFT/TD–DFT calculations). The results show that these Ln3+-based di-ureasil hybrids exhibit promising luminescent features, e.g., Eu3+-based materials are bright red emitters displaying quantum yields up to 0.50 ± 0.05. The luminescent color can be fine-tuned either by selection of adequate Ln3+ ions or by variation of the excitation wavelength. Accordingly, white light emission with CIE coordinates of (0.33, 0.35) under 310 nm irradiation was obtained. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessCommunication
Huge Enhancement of Luminescence from a Coaxial-Like Heterostructure of Poly(3-methylthiophene) and Au
Polymers 2018, 10(4), 414; https://doi.org/10.3390/polym10040414 - 09 Apr 2018
Abstract
Recently, the light-matter interaction at nanoscale has attracted great interest from physicists, chemists and material scientists, as it gives peculiar optical properties that couldn’t be observed at the bulk scale. The synthesis and characterization of organic-inorganic heterostructures forming quantum dots, nanowires or nanotubes [...] Read more.
Recently, the light-matter interaction at nanoscale has attracted great interest from physicists, chemists and material scientists, as it gives peculiar optical properties that couldn’t be observed at the bulk scale. The synthesis and characterization of organic-inorganic heterostructures forming quantum dots, nanowires or nanotubes provide opportunities to understand their photophysical mechanism and to apply optoelecronic devices. Herein, we report a huge enhanced luminescence in a coaxial-like heterostructured poly (3-methylthiophene) (P3MT) with Au. We electrochemically synthesized P3MT nanowires (NWs) on a nanoporous template, and sequentially deposited Au on the surface of P3MT NWs. The diameter of heterostructured P3MT/Au NWs was about 200 nm, where the cladding-shape Au were about 10 nm. The visible range absorbance, with two new absorption peaks of P3MT/Au NWs, was significantly increased compared with that of P3MT NWs. Accordingly, the photoluminescence (PL) of a P3MT/Au NW was enormously increased; up to 170 times compared to that of P3MT NWs. More interestingly, an unexpected enhancement of PL was observed from cross-junction point of P3MT/Au NWs. The abnormal PL properties of P3MT/Au NWs were attributed to the charge transfer and the surface plasmon resonance between the cladding-shape Au and the core-shape P3MT, which resulted in the enhanced quantum yield. This incites us to reconsider the light-matter interaction in polymer-metal hybrid structures applicable for high-performance optoelectronic devices. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Incorporation of Coumarin-Based Fluorescent Monomers into Co-Oligomeric Molecules
Polymers 2018, 10(4), 396; https://doi.org/10.3390/polym10040396 - 03 Apr 2018
Cited by 1
Abstract
With the purpose of modifying organic fluorescent dyes based on the coumarin scaffold, and developing and evaluating a route to its incorporation into a polymeric backbone, a study was conducted on the co-polymerization of 3-vinylcoumarins with styrene and methyl acrylate using 2,2-azobis(isobutyronitrile) (AIBN) [...] Read more.
With the purpose of modifying organic fluorescent dyes based on the coumarin scaffold, and developing and evaluating a route to its incorporation into a polymeric backbone, a study was conducted on the co-polymerization of 3-vinylcoumarins with styrene and methyl acrylate using 2,2-azobis(isobutyronitrile) (AIBN) as the radical initiator. The structural and photophysical characterization proved the incorporation of the coumarin monomers into the polymeric chain and further showed a decrease in the fluorescence quantum yields in the co-oligomers. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Optical and Thermomechanical Properties of Doped Polyfunctional Acrylate Copolymers
Polymers 2018, 10(3), 337; https://doi.org/10.3390/polym10030337 - 19 Mar 2018
Abstract
Three different polyfunctional acrylate monomers—trimethylolpropantriacrylate (TMPTA), pentaerythritol triacrylate (PETA) and di(trimethylolpropane) tetraacrylate (DTTA)—have been used as comonomers in combination with a reactive resin consisting of poly(methylmethacrylate), dissolved in its monomer methylmethacrylate. Phenanthrene has been added to form a guest–host system. The level of [...] Read more.
Three different polyfunctional acrylate monomers—trimethylolpropantriacrylate (TMPTA), pentaerythritol triacrylate (PETA) and di(trimethylolpropane) tetraacrylate (DTTA)—have been used as comonomers in combination with a reactive resin consisting of poly(methylmethacrylate), dissolved in its monomer methylmethacrylate. Phenanthrene has been added to form a guest–host system. The level of phenanthrene present may be adjusted to tailor the refractive index in the system. Prior to curing, the shear rate and temperature-dependent viscosity as a function of the composition were measured. It could be demonstrated that, with respect to different shaping methods, a tailor-made flow behaviour can be adjusted. After thermally-induced polymerization, the resulting optical (refractive index, optical transmittance) and thermomechanical (glass transition behavior, Vickers hardness) properties were characterized. A significant refractive index increase—up to a value close to 1.56 (@589 nm)—under the retention of good optical transmittance was able to be obtained. In addition, the photopolymerization behaviour was investigated to overcome the undesirable oxygen inhibition effect during the light-induced radical polymerization of acrylates. The level of acrylate units in the copolymer can compensate for the plasticizing effect of the dopant phenanthrene, enabling higher concentrations of the dopant in the guest–host system and therefore larger refractive index values suitable for polymer waveguide fabrication. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Synthesis and Photovoltaic Properties of 2D-Conjugated Polymers Based on Alkylthiothienyl-Substituted Benzodithiophene and Different Accepting Units
Polymers 2018, 10(3), 331; https://doi.org/10.3390/polym10030331 - 18 Mar 2018
Cited by 5
Abstract
Two new low bandgap conjugated polymers, PBDTS-ID and PBDTS-DTNT, containing isoindigo (ID) and naphtho[1,2-c:5,6-c′]bis[1,2,5]thiadiazole (NT), respectively, as an electron-deficient unit and alkylthiothienyl-substituted benzodithiophene (BDTS) as an electron-rich unit, were designed and synthesized by palladium-catalyzed Stille polycondensation. Both polymers showed [...] Read more.
Two new low bandgap conjugated polymers, PBDTS-ID and PBDTS-DTNT, containing isoindigo (ID) and naphtho[1,2-c:5,6-c′]bis[1,2,5]thiadiazole (NT), respectively, as an electron-deficient unit and alkylthiothienyl-substituted benzodithiophene (BDTS) as an electron-rich unit, were designed and synthesized by palladium-catalyzed Stille polycondensation. Both polymers showed good thermal stability up to 330 °C and broad absorption ranging from 300 to 842 nm. Electrochemical measurement revealed that PBDTS-ID and PBDTS-DTNT exhibited relatively low-lying highest occupied molecular orbital energy levels at −5.40 and −5.24 eV, respectively. These features might be beneficial for obtaining reasonable high open-circuit voltage and high short-circuit current. Polymer solar cells (PSCs) were fabricated with an inverted structure of indium-tin oxide/poly(ethylenimine ethoxylate)/polymer:PC71BM/MoO3/Ag. As a preliminary result, the PSCs based on PBDTS-ID and PBDTS-DTNT exhibited moderate power conversion efficiencies of 2.70% and 2.71%, respectively. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Amphiphilic Quantum Dots with Asymmetric, Mixed Polymer Brush Layers: From Single Core-Shell Nanoparticles to Salt-Induced Vesicle Formation
Polymers 2018, 10(3), 327; https://doi.org/10.3390/polym10030327 - 16 Mar 2018
Cited by 1
Abstract
A mixed micelle approach is used to produce amphiphilic brush nanoparticles (ABNPs) with cadmium sulfide quantum dot (QD) cores and surface layers of densely grafted (σ = ~1 chain/nm2) and asymmetric (fPS = 0.9) mixed polymer brushes that contain [...] Read more.
A mixed micelle approach is used to produce amphiphilic brush nanoparticles (ABNPs) with cadmium sulfide quantum dot (QD) cores and surface layers of densely grafted (σ = ~1 chain/nm2) and asymmetric (fPS = 0.9) mixed polymer brushes that contain hydrophobic polystyrene (PS) and hydrophilic poly(methyl methacrylate) (PMAA) chains (PS/PMAA-CdS). In aqueous media, the mixed brushes undergo conformational rearrangements that depend strongly on prior salt addition, giving rise to one of two pathways to fluorescent and morphologically disparate QD-polymer colloids. (A) In the absence of salt, centrosymmetric condensation of PS chains forms individual core-shell QD-polymer colloids. (B) In the presence of salt, non-centrosymmetric condensation of PS chains forms Janus particles, which trigger anisotropic interactions and amphiphilic self-assembly into the QD-polymer vesicles. To our knowledge, this is the first example of an ABNP building block that can form either discrete core-shell colloids or self-assembled superstructures in water depending on simple changes to the chemical conditions (i.e., salt addition). Such dramatic and finely tuned morphological variation could inform numerous applications in sensing, biolabeling, photonics, and nanomedicine. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Photo-Polymerization in Chiral Dopant Liquid Crystal Cells via Holographic Exposure to Fabricate Polarization-Independent Phase Modulator with Fast Optical Response
Polymers 2018, 10(3), 315; https://doi.org/10.3390/polym10030315 - 14 Mar 2018
Cited by 1
Abstract
Small liquid crystal domains with random director distributions were obtained to show novel optical isotropy using a holographic exposure processes to treat chiral dopant liquid crystal cells in the isotropic phase (i.e., polymer-stabilized isotropic liquid crystal cells). The cells used to fabricate phase [...] Read more.
Small liquid crystal domains with random director distributions were obtained to show novel optical isotropy using a holographic exposure processes to treat chiral dopant liquid crystal cells in the isotropic phase (i.e., polymer-stabilized isotropic liquid crystal cells). The cells used to fabricate phase modulators showed unique performances, including low light scattering, polarization-independence, and fast optical response. Furthermore, an extra fluoro-surfactant dopant in cells showed that the phase modulators retained their performance but with considerable reduction of operating voltages, from 180 Vrms to 100 Vrms. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Holographic Lenses in an Environment-Friendly Photopolymer
Polymers 2018, 10(3), 302; https://doi.org/10.3390/polym10030302 - 11 Mar 2018
Cited by 6
Abstract
In this paper, we theoretically and experimentally evaluated the quality of volume phase transmission lenses stored in an environmentally friendly photopolymer. Holographic lenses (HLs) were obtained using symmetrical and asymmetrical experimental setups with the same positive and negative focal length and pupil diameter. [...] Read more.
In this paper, we theoretically and experimentally evaluated the quality of volume phase transmission lenses stored in an environmentally friendly photopolymer. Holographic lenses (HLs) were obtained using symmetrical and asymmetrical experimental setups with the same positive and negative focal length and pupil diameter. The image quality was evaluated from the calculation of the modulation transfer function (MTF) by capturing the point spread function (PSF) with a charge-coupled device (CCD). A maximum frequency of 14 L/mm, reaching an MTF value of 0.1, was obtained for a negative asymmetrically recorded HL, evaluated at 473 nm wavelength. A theoretical study of aberrations was carried out to qualitatively evaluate the experimental results obtained. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Effects of Charge Density on Photophysics and Aggregation Behavior of Anionic Fluorene-Arylene Conjugated Polyelectrolytes
Polymers 2018, 10(3), 258; https://doi.org/10.3390/polym10030258 - 02 Mar 2018
Cited by 1
Abstract
Three anionic fluorene-based alternating conjugated polyelectrolytes (CPEs) have been synthesized that have 9,9-bis(4-phenoxy-butylsulfonate) fluorene-2,7-diyl and 1,4-phenylene (PBS-PFP), 4,4′-biphenylene (PBS-PFP2), or 4,4″-p-terphenylene (PBS-PFP3) groups, and the effect of the length of the oligophenylene spacer on their aggregation and photophysics has been studied. [...] Read more.
Three anionic fluorene-based alternating conjugated polyelectrolytes (CPEs) have been synthesized that have 9,9-bis(4-phenoxy-butylsulfonate) fluorene-2,7-diyl and 1,4-phenylene (PBS-PFP), 4,4′-biphenylene (PBS-PFP2), or 4,4″-p-terphenylene (PBS-PFP3) groups, and the effect of the length of the oligophenylene spacer on their aggregation and photophysics has been studied. All form metastable dispersions in water, but can be solubilized using methanol, acetonitrile, or dioxane as cosolvents. This leads to increases in their emission intensities and blue shifts in fluorescence maxima due to break-up of aggregates. In addition, the emission maximum shifts to the blue and the loss of vibronic structure are observed when the number of phenylene rings is increased. Debsity Functional Theory (DFT) calculations suggest that this is due to increasing conformational flexibility as the number of phenylene rings increases. This is supported by increasing amplitude in the fast component in the fluorescence decay. The nonionic surfactant n-dodecylpentaoxyethylene glycol ether (C12E5) also breaks up aggregates, as seen by changes in fluorescence intensity and maximum. However, the loss in vibrational structure is less pronounced in this case, possibly due to a more rigid environment in the mixed surfactant-CPE aggregates. Further information on the aggregates formed with C12E5 was obtained by electrical conductivity measurements, which showed an initial increase in specific conductivity upon addition of surfactants, while at higher surfactant/CPE molar ratios a plateau was observed. The specific conductance in the plateau region decreased in the order PBS-PFP3 < PBS-PFP2 < PBS-PFP, in agreement with the change in charge density on the CPE. The reverse process of aggregate formation has been studied by injecting small volumes of solutions of CPEs dissolved at the molecular level in a good solvent system (50% methanol-water) into the poor solvent, water. Aggregation was monitored by changes in both fluorescence and light scattering. The rate of aggregation increases with hydrophobicity and concentration of sodium chloride but is only weakly dependent on temperature. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Optimization of Temperature Sensing with Polymer-Embedded Luminescent Ru(II) Complexes
Polymers 2018, 10(3), 234; https://doi.org/10.3390/polym10030234 - 26 Feb 2018
Cited by 4
Abstract
Temperature is a key parameter in many fields and luminescence-based temperature sensing is a solution for those applications in which traditional (mechanical, electrical, or IR-based) thermometers struggle. Amongst the indicator dyes for luminescence thermometry, Ru(II) polyazaheteroaromatic complexes are an appealing option to profit [...] Read more.
Temperature is a key parameter in many fields and luminescence-based temperature sensing is a solution for those applications in which traditional (mechanical, electrical, or IR-based) thermometers struggle. Amongst the indicator dyes for luminescence thermometry, Ru(II) polyazaheteroaromatic complexes are an appealing option to profit from the widespread commercial technologies for oxygen optosensing based on them. Six ruthenium dyes have been studied, engineering their structure for both photostability and highest temperature sensitivity of their luminescence. The most apt Ru(II) complex turned out to be bis(1,10-phenanthroline)(4-chloro-1,10-phenanthroline)ruthenium(II), due to the combination of two strong-field chelating ligands (phen) and a substituent with electron withdrawing effect on a conjugated position of the third ligand (4-Clphen). In order to produce functional sensors, the dye has been best embedded into poly(ethyl cyanoacrylate), due to its low permeability to O2, high temperature sensitivity of the indicator dye incorporated into this polymer, ease of fabrication, and excellent optical quality. Thermosensitive elements have been fabricated thereof as optical fiber tips for macroscopic applications (water courses monitoring) and thin spots for microscopic uses (temperature measurements in cell culture-on-a-chip). With such dye/polymer combination, temperature sensing based on luminescence lifetime measurements allows 0.05 °C resolution with linear response in the range of interest (0–40 °C). Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Tuning Light Emission towards White Light from a Naphthalenediimide-Based Entangled Metal-Organic Framework by Mixing Aromatic Guest Molecules
Polymers 2018, 10(2), 188; https://doi.org/10.3390/polym10020188 - 14 Feb 2018
Cited by 2
Abstract
Taking advantage of the outstanding properties of a naphthalenediimide-based entangled porous coordination polymer, a simple strategy for the achievement of white light emission is herein presented. The dynamic structural transformation of the [Zn2(bdc)2(dpNDI)]n metal-organic framework enhances the interactions [...] Read more.
Taking advantage of the outstanding properties of a naphthalenediimide-based entangled porous coordination polymer, a simple strategy for the achievement of white light emission is herein presented. The dynamic structural transformation of the [Zn2(bdc)2(dpNDI)]n metal-organic framework enhances the interactions with aryl-guests giving rise to different luminescence colors upon UV (ultraviolet) illumination. Thus, through the rational selection of those small aromatic guest molecules with different electron donor substituents at the appropriate proportion, the emission color was tuned by mixture ratio of guest molecules and even white light emission was achieved. Furthermore, domains in large crystals with a complementary response to linearly polarized light were noticed. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Trifluoromethyl-Substituted Large Band-Gap Polytriphenylamines for Polymer Solar Cells with High Open-Circuit Voltages
Polymers 2018, 10(1), 52; https://doi.org/10.3390/polym10010052 - 08 Jan 2018
Abstract
Two large band-gap polymers (PTPACF and PTPA2CF) based on polytriphenylamine derivatives with the introduction of electron-withdrawing trifluoromethyl groups were designed and prepared by Suzuki polycondensation reaction. The chemical structures, thermal, optical and electrochemical properties were characterized in detail. From the UV-visible [...] Read more.
Two large band-gap polymers (PTPACF and PTPA2CF) based on polytriphenylamine derivatives with the introduction of electron-withdrawing trifluoromethyl groups were designed and prepared by Suzuki polycondensation reaction. The chemical structures, thermal, optical and electrochemical properties were characterized in detail. From the UV-visible absorption spectra, the PTPACF and PTPA2CF showed the optical band gaps of 2.01 and 2.07 eV, respectively. The cyclic voltammetry (CV) measurement displayed the deep highest occupied molecular orbital (HOMO) energy levels of −5.33 and −5.38 eV for PTPACF and PTPA2CF, respectively. The hole mobilities, determined by field-effect transistor characterization, were 2.5 × 10−3 and 1.1 × 10−3 cm2 V−1 S−1 for PTPACF and PTPA2CF, respectively. The polymer solar cells (PSCs) were tested under the conventional device structure of ITO/PEDOT:PSS/polymer:PC71BM/PFN/Al. All of the PSCs showed the high open circuit voltages (Vocs) with the values approaching 1 V. The PTPACF and PTPA2CF based PSCs gave the power conversion efficiencies (PCEs) of 3.24% and 2.40%, respectively. Hence, it is a reliable methodology to develop high-performance large band-gap polymer donors with high Vocs through the feasible side-chain modification. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Effects of Fluoro Substitution on the Electrochromic Performance of Alternating Benzotriazole and Benzothiadiazole-Based Donor–Acceptor Type Copolymers
Polymers 2018, 10(1), 23; https://doi.org/10.3390/polym10010023 - 25 Dec 2017
Cited by 5
Abstract
Two new donor–acceptor type electrochromic copolymers containing non-fluorinated and di-fluorinated benzothiadiazole analogues, namely P(TBT-TBTh) and P(TBT-F-TBTh), were synthesized successfully through chemical polymerization. Both polymers were measured by cyclic voltammetry, UV-vis spectroscopy, colorimetry and thermogravimetric analysis to study the influence of fluoro substitution on [...] Read more.
Two new donor–acceptor type electrochromic copolymers containing non-fluorinated and di-fluorinated benzothiadiazole analogues, namely P(TBT-TBTh) and P(TBT-F-TBTh), were synthesized successfully through chemical polymerization. Both polymers were measured by cyclic voltammetry, UV-vis spectroscopy, colorimetry and thermogravimetric analysis to study the influence of fluoro substitution on the electrochromic performance. The results demonstrated that the two polymer films displayed well-defined redox peaks in pairs during the p-type doping, and showed distinct color change from dark gray blue to light green for P(TBT-TBTh) with the band gap of 1.51 eV, and from gray blue to celandine green for P(TBT-F-TBTh) with the band gap of 1.58 eV. P(TBT-F-TBTh) presented lower highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, and better stability than P(TBT-TBTh). It was found that the two fluorine atoms participated in not only inductive effects but also mesomeric effects in the P(TBT-F-TBTh) backbone. In addition, the polymers exhibited high optical contrasts, short response time, and favorable coloration efficiency, especially in the near infrared region. The characterization results indicated that the two reported polymers can be the potential choice as electrochromic materials. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Characterization of Chromatic Dispersion and Refractive Index of Polymer Optical Fibers
Polymers 2017, 9(12), 730; https://doi.org/10.3390/polym9120730 - 20 Dec 2017
Cited by 4
Abstract
The chromatic dispersion and the refractive index of poly(methyl methacrylate) polymer optical fibers (POFs) have been characterized in this work by using a tunable femtosecond laser and a Streak Camera. The characterization technique is based on the measurement of the time delays of [...] Read more.
The chromatic dispersion and the refractive index of poly(methyl methacrylate) polymer optical fibers (POFs) have been characterized in this work by using a tunable femtosecond laser and a Streak Camera. The characterization technique is based on the measurement of the time delays of light pulses propagating along POFs at different wavelengths. Polymer fibers of three different lengths made by two manufacturers have been employed for that purpose, and discrepancies lower than 3% have been obtained in all cases. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Electrosynthesis of Aromatic Poly(amide-amine) Films from Triphenylamine-Based Electroactive Compounds for Electrochromic Applications
Polymers 2017, 9(12), 708; https://doi.org/10.3390/polym9120708 - 13 Dec 2017
Cited by 14
Abstract
Two electropolymerizable monomers with a methoxytriphenylamine core linked via amide groups to two triphenylamine (TPA) or N-phenylcarbazole (NPC) terminal groups, namely 4,4′-bis(4-diphenylaminobenzamido)-4′′-methoxytriphenylamine (MeOTPA-(TPA)2) and 4,4′-bis(4-(carbazol-9-yl)benzamido)-4′′-methoxytriphenylamine (MeOTPA-(NPC)2), were synthesized and characterized by FTIR and 1H NMR spectroscopy, mass [...] Read more.
Two electropolymerizable monomers with a methoxytriphenylamine core linked via amide groups to two triphenylamine (TPA) or N-phenylcarbazole (NPC) terminal groups, namely 4,4′-bis(4-diphenylaminobenzamido)-4′′-methoxytriphenylamine (MeOTPA-(TPA)2) and 4,4′-bis(4-(carbazol-9-yl)benzamido)-4′′-methoxytriphenylamine (MeOTPA-(NPC)2), were synthesized and characterized by FTIR and 1H NMR spectroscopy, mass spectrometry, and cyclic voltammetry. The electrochemical polymerization reactions of these MeOTPA-cored monomers over indium tin oxide (ITO) electrode allow the generation of electroactive poly(amide-amine) films. The electro-generated polymer films exhibited reversible redox processes and multi-colored electrochromic behaviors upon electro-oxidation, together with moderate coloration efficiency and cycling stability. The optical density changes (ΔOD) were observed in the range of 0.18–0.68 at specific absorption maxima, with the calculated coloration efficiencies of 42–123 cm2/C. Single-layer electrochromic devices using the electrodeposited polymer films as active layers were fabricated for the preliminary investigation of their electrochromic applications. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
The Availability of Neutral Cyan, Green, Blue and Purple Colors from Simple D–A Type Polymers with Commercially Available Thiophene Derivatives as the Donor Units
Polymers 2017, 9(12), 656; https://doi.org/10.3390/polym9120656 - 29 Nov 2017
Cited by 5
Abstract
In this paper, the Stille coupling reaction was used to prepare four donor–acceptor–donor (D–A–D) type monomers. For this purpose, 2,3-bis(4-methoxyphenyl) quinoxaline was used as the acceptor unit, and thiophene derivatives (3,4-ethylenedioxythiophene, or EDOT; 3-methoxythiophene, or MOTh; 3-methylthiophene, or MTh; and thiophene, or Th) [...] Read more.
In this paper, the Stille coupling reaction was used to prepare four donor–acceptor–donor (D–A–D) type monomers. For this purpose, 2,3-bis(4-methoxyphenyl) quinoxaline was used as the acceptor unit, and thiophene derivatives (3,4-ethylenedioxythiophene, or EDOT; 3-methoxythiophene, or MOTh; 3-methylthiophene, or MTh; and thiophene, or Th) were used as the donor units. The monomers were polymerized to the corresponding polymers by the cyclic voltammetry (CV) or potentiostatic method. The band gaps and the adsorption profiles of the polymers were finely tuned with the incorporation of the different thiophene units. All four polymers have low band gaps, and switched between the colored neutral states and the highly transmissive oxidized state. We were successfully able to obtain the valuable neutral colors of cyan, green, blue, and violet for the polymers employing EDOT, MOTh, MTh, and Th as the donor unit, respectively. Furthermore, electrochromic kinetic investigations showed that all four polymers displayed excellent optical contrasts (ΔT%), fast switching times, high coloration efficiencies, and robust stabilities, indicating that these four polymers are probably promising choices for developing electrochromic devices. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Time Evolution of the Excimer State of a Conjugated Polymer Laser
Polymers 2017, 9(12), 648; https://doi.org/10.3390/polym9120648 - 27 Nov 2017
Cited by 3
Abstract
An excited dimer is an important complex formed in nano- or pico-second time scales in many photophysics and photochemistry applications. The spectral and temporal profile of the excimer state of a laser from a new conjugated polymer, namely, poly (9,9-dioctylfluorenyl-2,7-diyl) (PFO), under several [...] Read more.
An excited dimer is an important complex formed in nano- or pico-second time scales in many photophysics and photochemistry applications. The spectral and temporal profile of the excimer state of a laser from a new conjugated polymer, namely, poly (9,9-dioctylfluorenyl-2,7-diyl) (PFO), under several concentrations in benzene were investigated. These solutions were optically pumped by intense pulsed third-harmonic Nd:YAG laser (355-nm) to obtain the amplified spontaneous emission (ASE) spectra of a monomer and an excimer with bandwidths of 6 and 7 nm, respectively. The monomer and excimer ASEs were dependent on the PFO concentration, pump power, and temperature. Employing a sophisticated picosecond spectrometer, the time evolution of the excimer state of this polymer, which is over 400 ps, can be monitored. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Dual-Emissive Waterborne Polyurethanes Prepared from Naphthalimide Derivative
Polymers 2017, 9(9), 411; https://doi.org/10.3390/polym9090411 - 03 Sep 2017
Cited by 8
Abstract
Fluorescent and room-temperature phosphorescent (RTP) materials are widely used in bioimaging, chemical sensing, optoelectronics and encryption. Here, a series of single-component dual-emissive waterborne polyurethanes (WPUs) with both fluorescence and room-temperature phosphorescence were synthesized. Dye without halogen atom incorporated into WPUs can only exhibit [...] Read more.
Fluorescent and room-temperature phosphorescent (RTP) materials are widely used in bioimaging, chemical sensing, optoelectronics and encryption. Here, a series of single-component dual-emissive waterborne polyurethanes (WPUs) with both fluorescence and room-temperature phosphorescence were synthesized. Dye without halogen atom incorporated into WPUs can only exhibit fluorescence due to poor spin-orbit coupling. When bromine atom is introduced into dye, we found that WPUs can emit both fluorescence and room-temperature phosphorescence with lifetimes up to milliseconds because of enhanced spin-orbit coupling. Moreover, with an increase in dye concentrations in WPUs, excimers are formed due to the aggregation effect, and may promote communication between singlet and triplet states. At different dye concentrations, structural, thermal, and luminescent properties serve as the main focus. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Long Lived Photoexcitation Dynamics in π-Conjugated Polymer/PbS Quantum Dot Blended Films for Photovoltaic Application
Polymers 2017, 9(8), 352; https://doi.org/10.3390/polym9080352 - 10 Aug 2017
Cited by 4
Abstract
We used continuous wave photoinduced absorption (PIA) spectroscopy to investigate long-lived polarons in a blend of PbS quantum dot and regio-regular poly (3-hexylthiophene) (RR-P3HT). The charge transfer from RR-P3HT to PbS as well as from PbS to RR-P3HT were observed after changing the [...] Read more.
We used continuous wave photoinduced absorption (PIA) spectroscopy to investigate long-lived polarons in a blend of PbS quantum dot and regio-regular poly (3-hexylthiophene) (RR-P3HT). The charge transfer from RR-P3HT to PbS as well as from PbS to RR-P3HT were observed after changing the capping ligand of PbS from a long chain molecular to a short one. Therefore, PbS could be used to extend the working spectral range in hybrid solar cells with a proper capping ligand. However, we found that the recombination mechanism in the millisecond time region is dominated by the trap/defects in blended films, while it improves to a bimolecular recombination partially after ligand exchange. Our results suggest that passivating traps of nanocrystals by improving surface ligands will be crucial for relevant solar cell applications. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Synthesis of Novel Hyperbranched Polybenzo-Bisthiazole Amide with Donor–Acceptor (D-A) Architecture, High Fluorescent Quantum Yield and Large Stokes Shift
Polymers 2017, 9(8), 304; https://doi.org/10.3390/polym9080304 - 25 Jul 2017
Abstract
Two novel highly fluorescent hyperbranched polybenzobisthiazole amides with a donor–acceptor architecture and large Stokes shift were rationally designed and synthesized. The chemical structures of the prepared hyperbranched polymers were characterized using Fourier Transform Infrared Spectroscopy (FTIR) analysis, Hydrogen Nuclear Magnetic Resonance (1 [...] Read more.
Two novel highly fluorescent hyperbranched polybenzobisthiazole amides with a donor–acceptor architecture and large Stokes shift were rationally designed and synthesized. The chemical structures of the prepared hyperbranched polymers were characterized using Fourier Transform Infrared Spectroscopy (FTIR) analysis, Hydrogen Nuclear Magnetic Resonance (1H-NMR) analysis, and Gel Permeation Chromatography (GPC) analysis. These two polymers were soluble in dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF), and their DMSO and DMF solutions emitted strong green light (517–537 nm) with high quantum yields (QYs) and large Stokes shifts. Their relative fluorescence QYs in the DMSO solution were calculated as 77.75% and 81.14% with the Stokes shifts of 137 nm (0.86 eV) and 149 nm (0.92 eV) for HP–COOH and HP–NH2, respectively, using quinine sulfate as the standard. In the DMF solution, the QYs of HP–COOH and HP–NH2 were calculated as 104.65% and 118.72%, with the Stokes shifts of 128 nm (0.79 eV) and 147 nm (0.87 eV), respectively. Their films mainly emitted strong blue light with the maximum emission wavelengths of 436 nm and 480 nm for HP–COOH and HP–NH2, respectively. The Stokes shifts for HP–COOH and HP–NH2 films were 131 nm (0.42 eV) and 179 nm (0.86 eV), respectively. They are promising candidates for luminescent solar concentrators and blue light emitting materials. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessArticle
Three Carbazole-Based Polymers as Potential Anodically Coloring Materials for High-Contrast Electrochromic Devices
Polymers 2017, 9(7), 284; https://doi.org/10.3390/polym9070284 - 18 Jul 2017
Cited by 10
Abstract
Three carbazole-based conjugated polymers (poly(3,6-di(2-thienyl)carbazole) (PDTC), poly(2,7-bis(carbazol-9-yl)-9,9-spirobifluorene) (PS2CBP), and poly(3,6-bis(N-carbazole)-N-ethylcarbazole) (PCEC)) are synthesized using electrochemical polymerization. The spectroelectrochemical studies indicate that the PDTC, PS2CBP, and PCEC films show reversible electrochromic behaviors in their redox states, and the PS2CBP film [...] Read more.
Three carbazole-based conjugated polymers (poly(3,6-di(2-thienyl)carbazole) (PDTC), poly(2,7-bis(carbazol-9-yl)-9,9-spirobifluorene) (PS2CBP), and poly(3,6-bis(N-carbazole)-N-ethylcarbazole) (PCEC)) are synthesized using electrochemical polymerization. The spectroelectrochemical studies indicate that the PDTC, PS2CBP, and PCEC films show reversible electrochromic behaviors in their redox states, and the PS2CBP film shows a distinct color transition with four various colors (gray at 0 V, grayish-green at 1.0 V, moss green at 1.2 V, and foliage green at 1.4 V). The maximum optical contrast of the PS2CBP and PCEC films is 39.83% at 428 nm and 32.41% at 420 nm, respectively, in an ionic liquid solution. Dual-type electrochromic devices (ECDs) that employ PDTC, PS2CBP, or PCEC film as an anodic layer, and PProDOT-Et2 film as a cathodic layer, were constructed. The as-prepared PCEC/PProDOT-Et2 ECD shows high optical contrast (38.25% at 586 nm) and high coloration efficiency (369.85 cm2 C−1 at 586 nm), and the PS2CBP/PProDOT-Et2 ECD shows high optical contrast (34.45% at 590 nm), good optical memory, and good long-term cycling stability. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessReview
Optical Fiber Sensors Based on Polymeric Sensitive Coatings
Polymers 2018, 10(3), 280; https://doi.org/10.3390/polym10030280 - 07 Mar 2018
Cited by 9
Abstract
Polymer technology is one of the fastest growing fields of contemporary research due to the possibility of using a wide variety of synthetic chemical routes for obtaining a polymeric network with a well-defined structure, resulting in materials with outstanding macroscopic properties. Surface engineering [...] Read more.
Polymer technology is one of the fastest growing fields of contemporary research due to the possibility of using a wide variety of synthetic chemical routes for obtaining a polymeric network with a well-defined structure, resulting in materials with outstanding macroscopic properties. Surface engineering techniques based on the implementation of polymeric structures can be used as an interesting tool for the design of materials with functional properties. In this sense, the use of fabrication techniques for the design of nanostructured polymeric coatings is showing an important growth due to the intrinsic advantages of controlling the structure at a nanoscale level because physical, chemical, or optical properties can be considerably improved in comparison with the bulk materials. In addition, the presence of these sensitive polymeric coatings on optical fiber is a hot topic in the scientific community for its implementation in different market niches because a wide variety of parameters can be perfectly measured with a high selectivity, sensitivity, and fast response time. In this work, the two main roles that a polymeric sensitive matrix can play on an optical fiber for sensing applications are evaluated. In a first section, the polymers are used as a solid support for the immobilization of specific sensitive element, whereas in the second section the polymeric matrix is used as the chemical transducer itself. Additionally, potential applications of the optical fiber sensors in fields as diverse as biology, chemistry, engineering, environmental, industry or medicine will be presented in concordance with these two main roles of the polymeric sensitive matrices. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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Open AccessReview
[email protected] Nanoparticles Prepared via RAFT Polymerization for Opto-Biodetection
Polymers 2018, 10(2), 189; https://doi.org/10.3390/polym10020189 - 14 Feb 2018
Cited by 3
Abstract
Colloidal gold nanoparticles (Au NPs) have been used in several biological applications, which include the exploitation of size- and shape-dependent Localized Surface Plasmon Resonance (LSPR) in biosensing devices. In order to obtain functional and stable Au NPs in a physiological medium, surface modification [...] Read more.
Colloidal gold nanoparticles (Au NPs) have been used in several biological applications, which include the exploitation of size- and shape-dependent Localized Surface Plasmon Resonance (LSPR) in biosensing devices. In order to obtain functional and stable Au NPs in a physiological medium, surface modification and functionalization are crucial steps in these endeavors. Reversible addition-fragmentation chain transfer (RAFT) polymerization meets this need offering the possibility of control over the composition and architecture of polymeric shells coating Au NPs. Furthermore, playing with a careful choice of monomers, RAFT polymerization allows the possibility to design a polymer shell with the desired functional groups aiming at Au based nanocomposites suitable for biorecognition and biotargeting. This review provides important aspects concerning the synthesis and optical properties of Au NPs as well as concepts of RAFT polymerization. Understanding these concepts is crucial to appreciate the chemical strategies available towards RAFT-polymer coated Au core-shell nanostructures, which are here reviewed. Finally, examples of applications in opto-biodetection devices are provided and the potential of responsive “smart” nanomaterials based on such structures can be applied to other biological applications. Full article
(This article belongs to the Special Issue Polymeric Materials for Optical Applications)
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