Thin Films Of Poly Research Articles

Dual Emission from Precious Metal-Free Luminophores Consisting of C, H, O, Si, and S/P at Room Temperature.

Fluorescence-phosphorescence dual-emissive compounds are valuable tools for ratiometric luminescence sensing. Herein, it is reported that 2,5-bis(phenylsulfonyl)- and 2,5-bis[bis(4-methoxyphenyl)phosphinyl]-1,4-disiloxybenzenes exhibit dual emission with emission peaks that were easily identified without performing time-gated measurement. The disiloxybenzenes in powder simultaneously fluoresced and phosphoresced at 358-374 and 457-470 nm, respectively, under vacuum. The intensity ratios of the phosphorescence/fluorescence maxima of the disiloxybenzenes in powder and in a thin film of poly(methyl methacrylate) were sensitive to temperature and molecular oxygen, respectively. The plots of the relative intensity versus temperature or partial pressure of molecular oxygen were well fitted with calibration curves defined by an exponential approximation with excellent correlation coefficients R2 (0.9708-0.9921), demonstrating the high potential of the disiloxybenzenes as precious metal-free probes applicable to ratiometric luminescence sensing.

A Facile Surface Functionalization Method for Polymers Using a Nonsolvent.

Surface treatment of polymeric solids without impairing their bulk properties is a crucial functionalization strategy for the promotion of their wider application. We here propose a facile method using a nonsolvent which can subtly alter or swell the polymer surface to be modified. A thin film of poly(methyl methacrylate) (PMMA) was immersed in a methanol solution of poly(2-methoxyethyl acrylate) (PMEA). Electron spectroscopy for chemical analysis and neutron reflectometry revealed that a PMEA layer formed on the PMMA film with a diffused interface. The PMEA layer was very swollen in water and exhibited the ability to suppress serum protein adsorption and platelet adhesion on it. The functionalization technique using a nonsolvent was also applicable to the surface of other polymeric solids such as polyurethane.

PMMA Thin Film with Embedded Carbon Quantum Dots for Post-Fabrication Improvement of Light Harvesting in Perovskite Solar Cells.

Perovskite solar cells (PSCs) with a standard sandwich structure suffer from optical transmission losses due to the substrate and its active layers. Developing strategies for compensating for the losses in light harvesting is of significant importance to achieving a further enhancement in device efficiencies. In this work, the down-conversion effect of carbon quantum dots (CQDs) was employed to convert the UV fraction of the incident light into visible light. For this, thin films of poly(methyl methacrylate) with embedded carbon quantum dots (CQD@PMMA) were deposited on the illumination side of PSCs. Analysis of the device performances before and after application of CQD@PMMA photoactive functional film on PSCs revealed that the devices with the coating showed an improved photocurrent and fill factor, resulting in higher device efficiency.

Fabrication and In Situ Characterization of Au@poly(ortho-aminophenol-co-ortho-phenylenediamine)/tiO2 Nanocomposite for Use In Electrochemical Sensing of Ampicillin Antibiotic

An electrochemical sensor based on Au/poly(ortho-aminophenol-co-ortho-phenylenediamine)/TiO2 nanocomposite ((Au/P(OAP-co-OPD)/TiO2)) to detect ampicillin (AMP) antibiotic was developed. The thin films of poly(ortho-aminophenol) (POAP), poly(ortho-phenylenediamine) (POPD), P(OAP-co-OPD), POAP/TiO2, POPD/TiO2 and (P(OAP-co-OPD)/TiO2)) nanocomposites were synthesized on gold electrodes by in situ electrocopolymerization method and characterized by CV, FT-IR, SEM, EIS, in situ resistivity measurements and in situ UV-visible spectroelectrochemistry. Two mechanism for copolymerization of OAP and OPD were suggested. In order to achieve a reproducible state of the sensing, the current changes were recorded for nanocomposites electrodes over time using the double chronoamperometric technique. Between the modified electrodes, Au/(POAP-co-POPD)/TiO2 nanocomposite exhibited high conductivity and sensitivity, excellent activity and long-term stability for detecting AMP antibiotic with a limit of detection down to 0.28 nM. The reproducibility of the Au/Cop. A/TiO2 nanocomposites sensors to lowest AMP concentration contents was observed approximately 6%–8% changes. The interference effects of four selected antibiotics on AMP for Au/Cop. A/TiO2 nanocomposites electrode were investigated. The response signal indicating that the sensor can not detect the target molecules within the different concentration range solutions. The results in the analysis of AMP on Au/P(OAP-co-POPD)/TiO2 sensor demonstrates that the obtain electrode is suitable as a promising candidates for electrochemical sensor applications.

Thin films of poly(vinylidene fluoride-co-hexafluoropropylene)-ionic liquid mixtures as amperometric gas sensing materials for oxygen and ammonia.

Gas sensors are important devices used to monitor the type and amount of gas present. Amperometric gas sensors - based on measuring the current upon an applied potential - have been progressing towards miniaturised designs that are smaller, lower cost, faster responding and more robust compared to commercially available sensors. In this work, a planar thin-film electrode device is employed for gas sensing with a thin layer of gel polymer electrolyte (GPE). The GPE consists of a room temperature ionic liquid (RTIL, with two different imidazolium cations and the tetrafluoroborate [BF4]- anion) mixed with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). The polymer acts as a scaffold, with the RTIL ions able to flow within the porous percolated channels, resulting in a highly robust gel with high conductivity. The chemical nature of the polymer allows thin-films (ca. 6 μm) to be evenly dropcast onto planar electrode devices, using minimal amounts of material. Remarkably, no significant effect of resistance was observed in the voltammetric response with such thin films. Oxygen (O2) and ammonia (NH3) gases were detected in the concentration ranges 1-20% O2 and 1-10 ppm NH3 in the two GPEs using both linear sweep voltammetry (LSV) and long-term chronoamperometry (LTCA). LTCA was the preferred detection method for both gases due to the steady-state current response compared to the sloping current response from LSV. The thin nature of the film gave fast response times for both gases - less than 10 seconds for O2 and ca. 40 seconds for NH3 - easily rivaling the commercially available porous electrode designs and allowing for continuous monitoring of gas concentrations. These materials appear to be highly promising candidates as gas detection electrolytes in miniaturised devices, with accurate and fast responses in both the cathodic and anodic potential regions.

In Situ-Fabricated Hydrogel Polymer—Semiconductor Nanocomposite Thin Film as a Highly Efficient and Robust Electrocatalyst for Hydrogen Evolution Reaction

Development of simple and facile protocols for the fabrication of highly efficient and robust catalytic electrodes for water splitting reactions is of paramount interest in establishing clean energy generation strategies. We show that hydrogel polymer thin films, in spite of their insulating character, enable a unique solution of wide scope, combining the ease of in situ fabrication of the electrocatalyst and efficient application. RuO2 nanoplates are generated within thin films of poly(hydroxyethyl methacrylate) (PHEMA) spin-cast on Ni foam, through mild thermal annealing. RuO2-PHEMA affects efficient hydrogen evolution reaction (HER) in an alkaline medium, with a very low overpotential of 30 mV at a current density of 10 mA cm–2 and stability for 24 h at 40 mA cm–2; Faradaic efficiency is 99.6%, and the turnover frequency is 24.2 s–1 at 100 mV overpotential. Experiments with a range of polymers establish a clear correlation between the swelling characteristic of the polymer and the overpotential for HER...

Plasma Enhanced Chemical Vapor Deposition of Poly(Cyclohexyl Methacrylate) as a Sacrificial Thin Film

In this study, thin films of poly(cyclohexyl methacrylate) (PCHMA) were deposited on silicon wafer using PECVD technique, in which the plasma power is inductively coupled through a quartz window using a planar-coil antenna, which was placed outside of the vacuum chamber. PCHMA is a desired sacrificial polymer for many applications because of its hydrophobicity and clean decomposition properties upon thermal annealing. During PECVD of PCHMA, the effects of plasma power and substrate temperature on the deposition rates and structural properties of as-deposited films were investigated. The highest deposition rate (46.5 nm/min) was observed at a low substrate temperature (15 °C) and at a high applied plasma power (30 W). FTIR and XPS analyses of the deposited films confirmed that the percentage of retained functional groups was increased if the intensity of applied plasma power was lowered. As-deposited PCHMA was found to decompose cleanly upon thermal annealing. The onset of thermal decomposition was 89 °C for the film deposited at 5 W applied plasma power.

CdSe/CdS–poly(cyclohexylethylene) thin film luminescent solar concentrators

Thin film luminescent solar concentrators are promising components of distributed power generation systems for building integrated photovoltaic applications. However, thin film geometries require high luminophore loading fractions to achieve sufficient absorption of sunlight, which, in the case of nanocrystal luminophores, can lead to aggregation and light scattering. In this work, we integrate CdSe/CdS nanocrystals into thin films of poly(cyclohexylethylene) at a range of loading fractions and characterize the composites with a combination of spectroscopic and simulation tools. We find that increased incident sunlight scattering is observed for the increasing luminophore loading fraction, but that the scattering is mostly limited to higher energy sunlight such that visible transmittance and haze of the samples are all greater than 89.7% and less than 8.3%, respectively. We then analyze the refractive index of the composite and show that the increase in loading fraction also affects the propagation of photoluminescence in the film, especially if the refractive index of the film is greater than that of the substrate. These studies show the importance of understanding the optical transport within thin films and provide design criteria to fabricate thin films for future implementation into building integrated photovoltaic applications.

Functional Changes during Electron-Beam Lithography of Biotinylated Poly(ethylene glycol) Thin Films.

In contrast to photolithography where particular wavelengths of light can couple to specific photochemistries, electron-beam lithography can drive competing chemistries. To separate surface-grafting, cross-linking, and chemical functionality, we studied the effects of 2 keV electrons on thin films of poly(ethylene glycol) end-functionalized with hydroxyls (PEG-OH) or biotins (PEG-B). Similarities in the dose-dependent thickness changes of the patterned PEGs indicate that surface grafting and cross-linking primarily involve the ethylene oxide main chain. While higher doses create thicker patterns with more biotin, the concurrent increase in thiol reactivity indicates that cross-linking competes with biotin degradation. The dose window for optimal e-beam patterning of biotinylated PEG is very narrow. Biotin is entirely consumed at higher doses. Its modified functionality is reactive with 5-((2-(and-3)-S-(acetylmercapto) succinoyl) amino) (SAMSA). This effect creates a dose-dependent orthogonal functionality that can be patterned from a single precursor thin film.

Stability of Polymer Coatings on Nebulizer Membranes During Aerosol Generation

The dimensions of orifices found in aperture plates used for nebulization can be modified by thin polymer coatings with the aim to control the size distribution of the generated aerosol droplets. However, the stability of such polymer coatings on the surface of nebulizer membranes during aerosol generation has not been elucidated. Nebulizer membranes made of stainless steel were covered with a thin film of poly(chloro-p-xylylene) (~1 μm) in the presence or absence of a silane-based adhesion promoter. Thereby, the orifice cross-sections of the nebulizer membrane were reduced by ~50%, accompanied by a remarkable decline in droplet size. Upon continuous nebulization of aqueous test liquids, the droplet size generated by the nonconditioned (no silane), poly(chloro-p-xylylene)-coated membranes reverted to that of the uncoated nebulizer membrane within ~5 min. By contrast, no such rapid return of droplet size to “baseline” values was noticed for the silane-conditioned, poly(chloro-p-xylylene)-coated counterparts. Scanning electron microscopy exhibited significant polymer detachment from the orifices of the nonconditioned (no silane) membranes and thus confirmed the findings from laser diffraction. Overall, silane-based adhesion promoters can increase the persistence of poly(chloro-p-xylylene) coatings on nebulizer membranes during aerosol generation.

Dual band amplified spontaneous emission in the blue in Poly(9,9-dioctylfluorene) thin films with phase separated glassy and β-phases

This paper reports the first experimental evidence of multiple band Amplified Spontaneous Emission (ASE) in the blue spectral range from a thin film of poly (9,9-dioctylfluorene) (PFO) with uniform thickness. In particular we demonstrate that ASE peaked at 453 nm and at 468 nm can be simultaneously obtained, with a threshold of about 255 μJcm−2 and 180 μJcm−2. This result is ascribed to the presence in the film of a uniform layer with PFO molecules fully in the glassy-phase spatially separated from micrometric clusters with molecules in the β-phase. The spatial separation between the two phases prevents energy transfer from the glassy to the β-phase, thus allowing both phases to show ASE. Beyond improving the understanding of the PFO based thin films with ASE our results open the way to the realization of broadly tunable optically pumped organic blue lasers.

Effect of Adjacent Hydrophilic Polymer Thin Films on Physical Aging and Residual Stress in Thin Films of Poly(butylnorbornene-ran-hydroxyhexafluoroisopropyl norbornene).

The properties of thin supported polymer films can be dramatically impacted by the substrate upon which it resides. A simple way to alter the properties of the substrate (chemistry, rigidity, dynamics) is by coating it with an immiscible polymer. Here we describe how ultrathin (ca. 2 nm) hydrophilic polymer layers of poly(acrylic acid), PAA, and poly(styrenesulfonate), PSS, impact the aging behavior and the residual stress in thin films of poly(butylnorbornene-ran-hydroxyhexafluoroisopropyl norbornene), BuNB-r-HFANB. The aging rate decreases as the film thickness (h) is decreased, but the extent of this change depends on the adjacent layer. Even for the thickest films (h>500 nm), there is a decrease in the aging rate at 100 °C when BuNB-r-HFANB is in contact with PSS. In an effort to understand the origins of these differences in the aging behavior, the elastic modulus and residual stress (σR) in the films were determined by wrinkling as a function of aging time. The change in the elastic modulus during aging does not appear to be directly correlated with the densification or expansion of the films, but the aging rates appear to roughly scale as hσR 1/3. These results illustrate that the physical aging of thin polymer films can be altered by adjacent polymers.

Poly(piperizinamide) with copper ion composite membranes: Application for mitigation of Hexaconazole from water and combat microbial contamination.

Thin film Poly(piperazine-amide) composite membranes using sequential interfacial polymerization with tuning by Cu2+ have brought significant findings in it. The hydrophobicity is relatively enhanced for the copper containing membranes. The membrane in which copper solution is applied prior to piperizine (Memb-III) exhibits higher hydrophobicity where as membrane (Memb-II) in which copper solution is applied following piperizine, possesses higher roughness compared to other two. Filtration experiments in terms of salts, mono/disaccharides and hexaconazole indicate that modified membranes are of different behaviours according to their sequence of preparative methods. Memb-III has shown lower SO4=/Cl- selectivity compared to Memb-II (i.e. 3.92), though they are in different range. The unmodified membrane (Memb-I) exhibits SO4=/Cl- selectivity 3.23 is in the same scale of Memb-III (2.27). Memb-III exhibits higher hexaconazole separation (91.5%) compared to Memb-II (i.e. 53.9%). The flux decline follows the order: field water > tap water > deionized water. The copper incorporated membrane (Memb-II) has shown a low flux decline compared to Memb-III as well as Memb-I. The antibacterial properties towards E. Coli and Bacillus subtilis are well reflected. The copper containing membranes have promising antibacterial properties and follows the order Memb-II > Memb-III > Memb-I.

Effect of the Density of Reactive Sites in P(S‐r‐MMA) Film during Al2O3 Growth by Sequential Infiltration Synthesis

AbstractSequential infiltration synthesis (SIS) consists in a controlled sequence of metal organic precursors and coreactant vapor exposure cycles of polymer films. Two aspects characterize an SIS process: precursor molecule diffusion within the polymer matrix and precursor molecule entrapment into polymer films via chemical reaction. In this paper, SIS process for the alumina synthesis is investigated using trimethylaluminum (TMA) and H2O in thin films of poly(styrene‐random‐methyl methacrylate) (P(S‐r‐MMA)) with variable MMA content. The amount of alumina grown in the P(S‐r‐MMA) films linearly depends on MMA content. A relatively low concentration of MMA in the copolymer matrix is enough to guarantee the volumetric growth of alumina in the polymer film. In pure polystyrene, metal oxide seeds grow in the subsurface region of the film. In situ dynamic spectroscopic ellipsometry analyses provide quantitative information about TMA diffusivity in pristine P(S‐r‐MMA) matrices as a function of MMA fraction, allowing further insight into the process kinetics as a function of the density of reactive sites in the polymer film. This work improves the understanding of infiltration synthesis mechanism and provides a practical approach to potentially expand the library of polymers that can be effectively infiltrated by introducing reactive sites in the polymer chain.

Quantitative assessment by local probe methods of the mechanical and electrical properties of inkjet-printed PEDOT:PSS thin films over Indium Tin Oxide substrates

Thin films of Poly(3,4-ethylenedioxythiophene) complexed with Poly(styrenesulfonate) (PEDOT:PSS) on Indium Tin Oxide (ITO) have been prepared by inkjet printing technology. The process allows obtaining thin films over large areas. A relatively broad range of thicknesses can be obtained by the addition of subsequent polymer layers resembling an additive manufacturing process. The resulting inkjet PEDOT:PSS films are homogeneous as regard both electrical and mechanical properties. In spite of the characteristic parallel line topography of these inkjet printed films, both the Quantitative Nanomechanical Mapping (QNM) and the Conductive-Atomic Force Microscope (C-AFM) characterization reveal homogeneous values throughout the polymer surface regardless of the welding zones. The results discussed in this work provide the basis for the application of inkjet printing as deposition method for electrically conducting PEDOT:PSS into a large area with mechanical stability. • Thin films of PEDOT:PSS on Indium Tin Oxide (ITO) have been prepared by inkjet printing technology over large areas. • Inkjet PEDOT:PSS films are homogeneous as regard both electrical and mechanical properties even through the welding zones.

Accidental Contamination of Substrates and Polymer Films by Organic Quantum Emitters.

We report the observation of ubiquitous contamination of dielectric substrates and poly(methyl methacrylate) matrices by organic molecules with optical transitions in the visible spectral range. Contamination sites of individual solvent-related fluorophores in thin films of poly(methyl methacrylate) constitute fluorescence hotspots with quantum emission statistics and quantum yields approaching 30% at cryogenic temperatures. Our findings not only resolve prevalent puzzles in the assignment of spectral features to various nanoemitters on bare dielectric substrates or in polymer matrices but also identify the means for the simple and cost-efficient realization of single-photon sources in the visible spectral range.

4,5-Diaminophthalimides: highly efficient solid-state fluorophores and turn-on type fluorescent probes for hydrazine

4,5-Bis(diarylamino)phthalimides in powder form and dispersed in a thin film of poly(methyl methacrylate) fluoresce in the green-to-orange and blue-to-green region, respectively, with high quantum yields.

Host–guest interactions of catechol and 4-ethylcatechol with surface-immobilized blue-box molecules

Surface-immobilized Blue Box molecules remove large amounts of the highly toxic catechol and 4-ethylcatechol from aqueous media, catalyzing the formation of a thin film of poly(catechol).

Characterization of NH\(_3\) Sensing Properties of P3HT+rGO+CNT Composite Films Made by Spin-coating

Thin films of poly(3-hexylthiophene) (P3HT) incorporated with reduced graphene oxide (rGO) and multi-walled carbon nanotubes (CNTs) were prepared by spin-coating technique. Atomic force microscope (AFM) surface morphology, UV-Vis spectra and NH3 gas sensing of the films were studied. Results showed that the P3HT embedded with a content of 20 wt.% of rGO and 10 % of CNTs (abbreviated to P3GC) resulted in the formation of nanostructured composites, exhibiting 1.50 nm-roughness surface and a semiconducting material with a bandgap of 1.92eV. These structure and composition of the P3GC film are appropriate for making film sensors whose resistance changes as a function of gas concentration. Monitoring ammonia gas by the sensors showed that the responding time of the sensing reached a value as fast as 30 s, the response at ammonia gas content of 10 ppm attained a value as large as 0.8% and the relative sensitivity was of 0.05 %/ppm.

Ferrocene Bearing Non-ionic Poly-aryl Tosylates: Synthesis, Characterization and Electron Beam Lithography Applications

The development of new organic-inorganic hybrid photoresists with optimal lithographic performances is an extremely important but challenging task. In this regard, we have synthesized a new family of homo- and hybrid-polymer resists based on 4-(tosyloxy)phenyl methacrylate (TPMA) and ferrocene methacrylate (FEMA) monomers for micro-/nano-lithography applications. The homo polymer resist, poly(TPMA), was synthesized by a free radical polymerization of TPMA monomer in ACN/THF (2:1, v/v) solvent system using azobisisobutyronitrile (AIBN) as the radical initiator. The hybrid copolymer resists, 2.0%-&4.0%-poly(FEMA-co-TPMA), containing 2.0 and 4.0 weight percentages of FEMA respectively, were synthesized by reacting FEMA (10 and 20% initial feed ratios respectively) and TPMA (90 and 80% initial feed ratios respectively) under similar reaction conditions. The ferrocene contents of the hybrid copolymers were calculated by proton NMR analysis. The potential of these polymer resists to pattern micro- and nano-features were tested under deep ultraviolet (DUV) and electron beam (e-beam) lithography tools respectively. The thin films formed by 4.0%-poly(FEMA-co-TPMA) exhibited high surface roughness in comparison to those of poly(TPMA) and 2.0%-poly(FEMA-co-TPMA) resists, probably due to the high ferrocene content of the former. The scanning electron microscopy (SEM) analysis of the e-beam exposed (dose 950 µC/cm2) thin films of poly(TPMA) revealed patterning of 40 nm (L/10S to L/4S), 30 nm (L/10S & L/5S) and 22 nm (L/10S) line features. Similarly, 2.0%-poly(FEMA-co-TPMA) patterned 40 nm (L/5S to L/S), 30 (L/5S to L/S) and 20 nm (L/5S & L/4S) line features under the e-beam exposure (dose 500 µC/cm2). The sensitivity and contrast values were calculated from the normalized remaining thickness (NRT) curve analysis as 270 µC/cm2; 5.2 and 153 µC/cm2; 1.98 respectively for poly(TPMA) and 2.0%-poly(FEMA-co-TPMA) resists. The present study therefore reveals that the incorporation of small amounts of ferrocene into the poly-aryl tosylate based resist formulations helps to enhance its sensitivity and resolution.