Characterization Of Polymer Films Research Articles

Nonenzymatic Sensor Based on Polythiophene/Titanium Dioxide (PTh/TiO2) Composite for the Determination of Malathion in Water

This study presents a novel nonenzymatic pesticide sensor utilizing a polythiophene/TiO2 (PTh/TiO2) film deposited on a glassy carbon (GC) electrode as the working electrode. The thiophene monomer was polymerized onto TiO2 by cyclic voltammetric method in the range of 0.0-2.5 V with 15 cycles at room temperature. The prepared electrode was used for the sensitive and selective detection of malathion thus providing the basis for facile electrochemical quantification. The surface morphology and crystal structure of the (PTh/TiO2) film were studied by SEM and XRD. FTIR was used for the structural analysis of (PTh/TiO2) film. FTIR results indicated that the PTh/TiO2composite structure was formed. The smooth surface morphology of PTh/TiO2 was supported by SEM results. XRD analysis verified that PTh is covered on TiO2 particles. The crystal phase of TiO2 was changed to amorph state after PTh modification. Additionally, the electrochemical characterization of polymer film and its response to malathion was examined by the CV method. Under optimized operational conditions, the response of the pesticide sensor was measured by CV in the range of -1 to 2.3 V versus the Ag/AgCl reference electrode due to the electrooxidation of malathion. The analysis focused on current values at -0.73 V, where the reduction of the PTh/TiO2 system occurred upon the addition of known amounts of malathion. The PTh/TiO2 composite film was sensitive to malathion in a linear range from 9.9 ppm to 436 ppm. The sensitivity was calculated as 57.5 μA/ µM cm2 whereas the detection limit was calculated as 7.45 µM. The maximum reaction rate was estimated as 767 μA. The developed sensor also showed good selectivity and reproducibility. The nonenzymatic pesticide sensor was successfully applied to detect malathion in tap water with at least 90% recovery.

PANDA: A self-driving lab for studying electrodeposited polymer films

We introduce the polymer analysis and discovery array (PANDA), an automated system for high-throughput electrodeposition and functional characterization of polymer films. The PANDA is a custom, modular, and low-cost system...

3D microscopic characterization of polymer films

3D microscopic characterization of polymer films

Permittivity and Loss Characterization of Polymer Films for Terahertz Applications

With the development of science, terahertz (THz) technology has matured gradually. More attention has been given to THz technology in recent years due to its superiority for non-destructive testing. Dielectric polymers are widely used in electrical engineering because of their unique electrical properties. Spectral detection plays a vital role in studying the internal motion and micro-scale forces. THz time-domain spectroscopy (THz-TDS) is a powerful complement to other spectroscopy techniques because of its unique frequency band that energetically vibrates and rotates the polymer structure. Herein, we apply THz-TDS with an effective frequency of 0.1–1 THz at 55% relative humidity. TDS at 0.1–1 THz to conduct fundamental research on several commonly utilized dielectric non-polar and polar polymer films including PC, FTPE, PMMA, HDPE, PA6, PET, PP. In this study, the THz complex refractive index and dielectric constants of various polymer films are determined and compared with previously reported values. In addition, the loss mechanism of THz radiation in polymers is characterized by correlating the absorption coefficients of the materials with the loss tangents. Herein, we demonstrate that the sample preparation significantly impacts the loss behavior of polymer materials and quantify the effect of crosslinking on the dielectric constant across the entire frequency band. The findings presented herein are expected to contribute to the design and development of optical and electronic devices in the future.

A Bacteria and Cell Repellent Zwitterionic Polymer Coating on Titanium Base Substrates towards Smart Implant Devices.

Biofouling and biofilm formation on implant surfaces are serious issues that more than often lead to inflammatory reactions and the necessity of lengthy post-operation treatments or the removal of the implant, thus entailing a protracted healing process. This issue may be tackled with a biocompatible polymeric coating that at the same time prevents biofouling. In this work, oxygen plasma-activated silanized titanium substrates are coated with poly(sulfobetaine methacrylate), a zwitterionic antibiofouling polymer, using photopolymerization. The characterization of polymer films includes FT-IR, AFM, and adhesion strength measurements, where adhesion strength is analyzed using a cylindrical flat punch indenter and water contact angle (WCA) measurements. Both cytotoxicity analysis with primary human fibroblasts and fluorescence microscopy with fibroblasts and plaque bacteria are also performed is this work, with each procedure including seeding on coated and control surfaces. The film morphology obtained by the AFM shows a fine structure akin to nanoropes. The coatings can resist ultrasonic and sterilization treatments. The adhesion strength properties substantially increase when the films are soaked in 0.51 M of NaCl prior to testing when compared to deionized water. The coatings are superhydrophilic with a WCA of 10° that increases to 15° after dry aging. The viability of fibroblasts in the presence of coated substrates is comparable to that of bare titanium. When in direct contact with fibroblasts or bacteria, marginal adhesion for both species occurs on coating imperfections. Because photopolymerization can easily be adapted to surface patterning, smart devices that promote both osseointegration (in non-coated areas) and prevent cell overgrowth and biofilm formation (in coated areas) demonstrate practical potential.

Unique combination of spatial and temporal control of maleic anhydride plasma polymerization

AbstractThe chemical properties of plasma polymers strongly depend on the operating conditions of plasma polymerization and impact their final application. Low‐pressure pulsed plasma polymerization of maleic anhydride was investigated at different positions from the glow discharge in a unique 1‐m‐long reactor. Based on a macroscopic approach, the growth kinetics of maleic anhydride plasma polymerization was investigated, leading to the identification of three growth regimes. The calculation of apparent activation energies associated with each regime and each position and the chemical characterization of polymer films by X‐ray photoelectron spectroscopy and attenuated total reflection–Fourier‐transform infrared as well as optical emission spectroscopy analyses of plasma species formed during deposition strongly indicate a combined spatial and temporal influence on the plasma polymerization kinetics.

Anion Effect on the Electropolymerization Reaction of Metanil Yellow in Aqueous Media and Characterization of Polymer Films

The electropolymerization of Metanil Yellow was investigated in aqueous solutions containing inorganic acids (sulphuric, hydrochloric, nitric, phosphoric and perchloric acid) as well as sulphonic acids (5-sulpho salicylic acid, sulphanilic acid, dodecylbenzene sulphonic acid, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) and lauryl sulphate in its acidic solution. By the inorganic ions the conductivity increased in the sulphate, chloride, nitrate, perchlorate serie. Of the organic sulphonic compounds 5-sulpho-salicylic acid was found to be a very efficient dopant in increasing polymer conductivity being obviously better than the other sulphonate anions. The formed conducting polymer was not suitable for detection of the corresponding anion. Nitrite ions completely diminished the electric properties of the polymer due to the reaction resulting nitrosamine.

Synthesis and characterization of polymeric films with stress-altered aluminum particle fillers

Processing and characterization of films synthesized with the blade casting method were studied. The films include 80 nm average diameter aluminum (nAl) particles combined with a solvent–binder system composed of acetone and dimethylformamide (DMF) co-solvent and Poly(vinylidene fluoride) (PVDF) binder. The nAl powder was stress-altered by annealing to 300 °C then quenching at two different cooling rates to induce elevated dilatational strain and stress within the nAl particles. Moreover, the annealing and quenching process dehydrated and dehydroxylated the surface enough to cause stress-altered particles to create more viscous slurries that produced a more porous film microstructure than untreated (UN) nAl powder. Density functional theory calculations revealed defective (i.e., dehydroxylated and dehydrated) sites on the stress-altered nAl particle surface may be responsible for the differences in nAl + PVDF reactivity that showed a higher enthalpy for aluminum-fluorine interface reactions for stress-altered nAl particles. Further, faster quenching created delamination at the core–shell interface and promoted greater energy conversion via a weaker, unsupported oxide shell that became less of a barrier for diffusion reactions. Results from this study provide insight on optimizing nAl particle properties for energy conversion using a method that could be applicable to a range of filler materials and influence bulk film properties.

Investigation of spectroscopic and thermo-mechanical behaviors of different phenanthroimidazole-azo dyes in solvent and polymer medium

The aim of this study is the investigation of the interaction between dyes and polymers which have different polarities. Dye doped polymer films have larger application areas because of the fact that dye is more stable when doped in polymer compared to solvent medium. However, dye dispersion in the polymer medium affects both the spectroscopic and mechanical properties of the polymer. The polymer-dye interaction must be high for a good dispersion,. In this study, polypropylene with apolar character and polymethylmethacrylate with polar groups were chosen as a solid phase to examine polymer-dye interactions. The photophysical properties of phenanthroimidazole-azo compounds synthesized previously were examined with UV–visible and fluorescence spectroscopy techniques in tetrahydrofuran and two polymer media. Also, photostability tests of azo dyes in THF and polymer films were performed. Surface roughness characterizations of polymer films were carried out with AFM. Additionally, the viscoelastic behaviors of the polymethylmethacrylate and polypropylene films under sinusoidal vibrations at different temperatures were studied by dynamic mechanical analysis technique.

Scanning Probe Microscopy for polymer film characterization in food packaging

Scanning probe microscopy (SPM) is a branch of microscopy allowing characterization of surfaces at the micro-scale by means of a physical probe (with a size of a few microns) raster scanning the sample. SPMs monitor the interaction between such probe and the surface and, depending on the specific physical principles causing the interaction, they allow generation of a quantitative map of topographic properties: geometrical, optical, electrical, magnetic, etc. This is of the greatest interest, in particular whenever functional surfaces have to be characterized in a quantitative manner. The present paper discusses the different applications of Scanning Probe Microscopy techniques for a thorough characterization of polymer surfaces, of specific interest in particular for the case of food packaging applications.

DETERMINATION OF THE STRUCTURE OF CARBON PARTICLES FORMED WHEN FORMING A POLYMER FILM IN A PLASMA CHEMICAL REACTOR

Abstract—We study the formation mechanism of carbon nanoparticles with simultaneous formation of a polystyrene film in a AC barrier corona discharge at atmospheric pressure. The importance of the research stems from the need to control the allotropic form of carbon nanoparticles, which affects the physical and technical characteristics of polymer films obtained by this method. It is shown that nucleation of polycrystalline onion-like carbon nanoparticle agglomerates is the basis for graphene flake formation in the corona sheath. Graphene flakes form from these nucleation sites in gas discharge streamers owing to the destruction of monomer molecules remaining in the agglomerates of nucleation sites. It was revealed that the allotropic form of such particles is determined not only by the energy—in this case the barrier corona discharge—but also by the ratio of the duration of its exposure to the characteristic destruction and formation times of covalent bonds participating in the particle process.

Flexible nanoenergy harvester using piezo-tribo functional polymer and carbon fibre as electrodes

Micro-energy harvesting has gained immense interest among the research community due to the requirement for self-powering of sensor units in unapproachable environments. Use of simple, low cost, flexible energy harvester aids generation of energy from ambient environments. The present work proposes two devices under test(DUT) with different electrodes namely copper(DUT1) and carbon fibre(DUT2), polymers Polyvinylidene fluoride (PVDF), Polydimethylsiloxane (PDMS) as a functional charge generating materials. The piezoelectric and triboelectric characterisation of polymer films is performed using Dynamic contact mode electrostatic force microscopy(DC-EFM). The proposed DUT1 and DUT2 generates an 8 Vpp and 9 Vpp during human finger tapping. The qualitative and quantitative analysis of DUT1 and DUT2 generated an output voltage of (8.5 V, 12.35 V) (high pressure),(13.5 V, 14.1 V) (285 rpm) respectively. The carbon fibre electrode based flexible device generated an output voltage of 9 V, 10 V and 2.275 V when subjected to biomechanical operations such as finger assisted tapping, press and release as well as bending operations. The device with copper electrode generated 0.32 nJ of energy and power density per unit area of 2.37 pW cm−2 in a single tap cycle. The DUT2 generated thrice the energy and power density than that of DUT1. The DUT2 thus promises to be an efficient, low-cost, flexible energy harvester with PVDF as well as PDMS polymers as a functional layer.

Dithienylpyrrole- and Tris[4-(2-thienyl)phenyl]amine-Containing Copolymers as Promising Anodic Layers in High-Contrast Electrochromic Devices

Three dithienylpyrrole- and tris[4-(2-thienyl)phenyl]amine-containing copolymers (P(MPS-co-TTPA), P(MPO-co-TTPA), and P(ANIL-co-TTPA)) were deposited on indium tin oxide (ITO) surfaces using electrochemical polymerization. Spectroelectrochemical characterizations of polymer films revealed that P(MPS-co-TTPA) film was light olive green, greyish-green, bluish grey, and grey in neutral state, intermediate state, oxidized state, and highly oxidized state, respectively, whereas P(MPO-co-TTPA) film was green moss, foliage green, dark greyish-green, and bluish-grey in neutral state, intermediate state, oxidized state, and highly oxidized state, respectively. The ΔTmax of P(MPS-co-TTPA) film at 964 nm, P(MPO-co-TTPA) film at 914 nm, and P(ANIL-co-TTPA) film at 960 nm were 67.2%, 60.7%, and 67.1%, respectively, and the coloration efficiency (η) of P(MPS-co-TTPA) film at 964 nm, P(MPO-co-TTPA) film at 914 nm, and P(ANIL-co-TTPA) film at 960 nm were calculated to be 260.3, 176.6, and 230.8 cm2 C−1, respectively. Dual type complementary colored electrochromic devices (ECDs) were constructed using P(MPS-co-TTPA), P(MPO-co-TTPA), or P(ANIL-co-TTPA) as anodic copolymer layer and PProDOT-Et2 as cathodic polymer layer. P(MPO-co-TTPA)/PProDOT-Et2 ECD revealed high ΔT (55.1%) and high η (766.5 cm2 C−1) at 580 nm. Moreover, P(MPS-co-TTPA)/PProDOT-Et2, P(MPO-co-TTPA)/PProDOT-Et2, and P(ANIL-co-TTPA)/PProDOT-Et2 ECDs showed satisfactory long-term cycling stability and optical memory.

Development and Bioanalytical Applications of a White Light Reflectance Spectroscopy Label-Free Sensing Platform.

The development of a sensing platform based on white light reflectance spectroscopy (WLRS) is presented. The evolution of the system, from polymer film characterization and sensing of volatile organic compounds to biosensor for the label-free determination of either high (e.g., proteins) or low molecular weight analytes (e.g., pesticides), is described. At the same time, the passage from single to multi-analyte determinations, and from a laboratory prototype set-up to a compact device appropriate for on-site determination, is outlined. The improvements made on both the sensor and the optical set-up, and the concomitant advances in the analytical characteristics and the robustness of the assays performed with the different layouts, are also presented. Finally, the future perspectives of the system, aiming for the creation of a standalone instrument to be used by non-experts, will be discussed.

An organic Schottky diode (OSD) based on a-silicon/polycarbazole contact

In this paper a novel organic Schottky diode (OSD) based on polycarbazole is proposed. The article presents fabrication and experimental characterization of an amorphous silicon/polycarbazole organic Schottky diode, particularly with configuration a-Si/p-PCz/ITO, wherein in the said novel Schottky diode amorphous silicon (a-Si) contact has been used in place of conventional metal contact on the semiconducting polymer to form a rectifying contact. The characterization of polymer film was done in terms of morphology, absorbance versus wavelength, bandgap and thickness. I–V measurement was performed by Semiconductor Device Analyzer. The electrical parameters such as barrier height, ideality factor, rectification ratio and reverse saturation current as extracted from I–V characteristics of the device were found to be much better than those reported earlier for Schottky diodes based on polycarbazole. The proposed organic Schottky diode (OSD) exhibits a very low dark current (∼10−14A) and is therefore expected to have great commercial applications.

Large-area dielectric breakdown performance of polymer films - part i: measurement method evaluation and statistical considerations on area-dependence

A multi-breakdown measurement method for large-area dielectric breakdown characterization of polymer films is presented and evaluated. Based on the self-healing breakdown capability of metalized film, large amount of breakdown data can be obtained from a relatively large total film area, thus enabling the execution of detailed breakdown performance analysis. The studied films include non-metalized laboratoryscale, pilot-scale and commercial capacitor-grade bi-axially oriented polypropylene films in the thickness range of 14-25 μm. With the active measurement area of 81 cm2 per sample, breakdown distributions covering total film areas of 486-972 cm2 are presented. Various aspects encompassing the sample film preparation, measurement procedure, breakdown progression, discharge event characterization, breakdown field determination, data validation and statistical analysis are discussed. Comparative small-area breakdown measurements were performed in order to study the relationship between the large-area multi-breakdown measurement method and a conventional small-area (1 cm2) manual breakdown measurement method. Implications of the areadependence and the applicability of the Weibull area-scaling are also discussed.

Adhesion of Poly(phenylene sulfide) Resin with Polymeric Film of Triazine Thiol on Aluminum Surface Modified by Anodic Oxidation.

Various surface modifications have been applied to improve the adhesion properties of aluminum for the cap plate and sealing quality of electrolyte on Li ion batteries. In this study, we have tried to find the effective condition for the polymerization of triazine thiols (TT) on modified aluminum surfaces by anodic aluminum oxide. Characterization of polymerized films on aluminum was explored by scanning electron microscopy, X-ray photoelectron spectroscopy, and secondary ion mass spectroscopy analysis. Scanning electron microscopy results reveal that meaningful roughness was formed on aluminum surfaces by anodic oxidation. Secondary ion mass spectroscopy analysis results represent that the peel strength was found to depend on film thickness and the composition of the adhesion layer. As a result, Al/PPS (polyphenylene sulfide) resin assemblies developed in this study have superior adhesive property. Therefore, these assemblies might be a viable candidate for a sealing technique for Li ion batteries.

Formulation and characterization of polymeric films containing combinations of antiretrovirals (ARVs) for HIV prevention.

To develop polymeric films containing dual combinations of anti-HIV drug candidate tenofovir, maraviroc and dapivirine for vaginal application as topical microbicides. A solvent casting method was used to manufacture the films. Solid phase solubility was used to identify potential polymers for use in the film formulation. Physical and chemical properties (such as water content, puncture strength and in vitro release) and product stability were determined. The bioactivity of the film products against HIV was assessed using the TZM-bl assay and a cervical explant model. Polymers identified from the solid phase solubility study maintained tenofovir and maraviroc in an amorphous state and prevented drug crystallization. Three combination film products were developed using cellulose polymers and polyvinyl alcohol. The residual water content in all films was <10% (w/w). All films delivered the active agents with release of >50% of film drug content within 30 min. Stability testing confirmed that the combination film products were stable for 12 months at ambient temperature and 6 months under stressed conditions. Antiviral activity was confirmed in TZM-bl and cervical explant models. Polymeric films can be used as a stable dosage form for the delivery of antiretroviral combinations as microbicides.

Electrosynthesis and characterization of polymer films on silicon substrates for applications in micromanipulation

Aniline and p-phenylenediamine were electrochemically oxidized in aqueous solutions by potentiodynamic deposition using cyclic voltammetry (CV) technique. Resulting polymer films electrodeposited on Si substrates were identified by infrared spectroscopy as polyaniline and poly(p-phenylenediamine) films. Cyclic voltammograms demonstrated that poly(p-phenylenediamine) films are non conductive contrary to polyaniline films which are conductive and electropolymerized through an autocatalytic mechanism. The morphological features (thickness, roughness, morphology) of the electrodeposited polymer films were determined using profilometry, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Adhesion force properties of polymer films were also studied by means of force–distance curves obtained by atomic force microscopy. The influence of some experimental parameters (potential scan rate, number of potential scans) was also studied. Thus, it was shown that the potential scan rate strongly influenced both morphological features and force adhesion, when the influence of the number of potential scans was less important. Under optimal conditions, it was possible to obtain low adhesive polymer films that could be useful to coat the fingers of the gripper and improve the Si objects manipulation tasks.

HYDROPHILIC BEHAVIOR OF POLYMER FILMS TREATED BY ATMOSPHERIC PRESSURE PLASMA

Experiment on the surface characteristics of polymer films (PC, PET, EVA) treated by atmospheric pressure plasma has been conducted. As the process parameters, we chose frequency, gas flow and treatment time. By measuring the contact angle, we scrutinized the effects of these parameters on the hydrophilic surface characteristics of polymer materials and found the optimum operating condition of each polymer for the highest hydropilicity. In the case of PC substrate, the contact angle was changed from 83.5 ± 1.1° (before plasma treatment) to 30.4 ± 0.4° (after plasma treatment) at the optimum operating condition of 30 kHz, CDA 0.6%, and repeated number of 7. In the case of PET substrate, the contact angle change was found from 59 ± 1.1° to 23.5 ± 1.7° at 20 kHz, CDA 0.6%, and repeated number of 7. In the case of EVA substrate, the contact angle of 84 ± 0.6° changed to 44.2 ± 1.2° at 30 kHz, CDA 0.6%, and repeated number of 7. The long-term stability of the hydrophilic surfaces and section morphology were also examined by SEM. As a roll-to-roll application, the adhesion force between PET and UV resin was measured to show initial increase according to the plasma treatment time, i.e., repeated number but finally saturated to show no meaningful change, which is in line with the behavior of the contact angle according to plasma treatment time.