Optical Properties Of Polymer Films Research Articles

Measurement and Analysis of Optical Properties of Polymer Films with Triangular Pyramid Optical Functional Texture

A poly (vinyl chloride) film with triangular pyramid array structure was designed and fabricated. In this paper, a plane to plane hot embossing technique is used to fabricate a triangular pyramid antireflection film on the surface of single crystal silicon solar cells. By testing the optical properties of optical functional textured films, it is found that the reflectivity of triangular pyramid textured films obtained by hot embossing is significantly lower than that of smooth flat films; The absorption and antireflection of high light on the film surface are obvious; The photoelectric conversion efficiency of the solar cell is further improved. Triangular pyramid optical functional structure has great potential in improving the performance of silicon solar cells, which can be applied to different types of solar cells. These improvements are of great significance to the commercialization of silicon solar cell devices.

Adaptable Eu-containing polymeric films with dynamic control of mechanical properties in response to moisture.

Self-healing polymers often have a trade-off between healing efficiency and mechanical stiffness. Stiff polymers that sacrifice their chain mobility are slow to repair upon mechanical failure. We herein report adaptable polymer films with dynamically moisture-controlled mechanical and optical properties, therefore having tunable self-healing efficiency. The design of the polymer film is based on the coordination of europium (Eu) with dipicolylamine (DPA)-containing random copolymers of poly(n-butyl acrylate-co-2-hydroxy-3-dipicolylamino methacrylate) (P(nBA-co-GMADPA)). The Eu-DPA complexation results in the formation of mechanically robust polymer films. The coordination of Eu-DPA has proven to be moisture-switchable given the preferential coordination of lanthanide metals to O over N, using nuclear magnetic resonance and fluorescence spectroscopy. Water competing with DPA to bind Eu3+ ions can weaken the cross-linking networks formed by Eu-DPA coordination, leading to the increase of chain mobility. The in situ dynamic mechanical analysis and ex situ rheological studies confirm that the viscofluid and the elastic solid states of Eu-polymers are switchable by moisture. Water speeds up the self-healing of the polymer film by roughly 100 times; while it can be removed after healing to recover the original mechanical stiffness of polymers.

Strain-optical behavior of polyethylene terephthalate film during uniaxial stretching investigated by Mueller matrix ellipsometry

Polyethylene terephthalate (PET) has gained widespread applications in various flexible devices where its optical properties after drawing process in manufacturing play a great importance in the performance of devices. In this work, the strain-optical behavior of pre-oriented polyethylene terephthalate (PET) film during uniaxial stretching is studied utilizing a proposed anisotropic model and Mueller matrix ellipsometry (MME). In the biaxial anisotropic model, the molecular chain orientation is correlated to the change of refractive indices and strain-induced birefringence, while the rotation of molecular chains is directly characterized by the rotation of principal optical axis. According to this model, the refractive indices, extinction coefficients and Euler angles extracted from measured Mueller matrix spectra can be used to interpret the micro-structural response of PET. A set of tensile tests have been carried out, with loading direction being varied. The results show that the strain-induced birefringence is linearly correlated to strain, while loading direction significantly affects the slope of achieved birefringence-strain curve. Meanwhile, the birefringence exhibits a positive linear relation with the orientation estimated by extinction coefficients. Through the analysis of the Euler angle ϕE, the principal optical axis rotating towards the tensile direction is accurately observed. Our results show that MME can provide a deep and systematic understanding of strain-optical behavior which can give accurate control of the optical properties of polymer films during deformation.

Electric and Optical Properties of Polyimide Surface Films Modified by Metals

<p>Electric and optical properties of polymer films, which were prepared on the basis of polyimides and metallized by binary aggregates Ag with Ni and Co, have been investigated. The metallized polyimide films with additional coating from Ni, Au and Rh have been studied too. It has been found that the temperature dependence of the specific surface resistance in the metallized films at the temperature from 25 up to 160 <sup>o</sup>C was in the well agreement with linear law. The specific surface resistance at 20 <sup>o</sup>C and temperature coefficient showed low values and was 0.16-2.24 Ω and 0.69×10<sup>-4</sup>-19.18×10<sup>-4</sup> K<sup>-1</sup> respectively. The film reflection coefficient in visible spectrum field at wavelength of 530 nm was 75% and essentially enlarged with wavelength increasing.</p>

Gold nanoparticle-polydimethylsiloxane films reflect light internally by optical diffraction and Mie scattering

Optical properties of polymer films embedded with plasmonic nanoparticles (NPs) are important in many implementations. In this work, optical extinction by polydimethylsiloxane (PDMS) films containing gold (Au) NPs was enhanced at resonance compared to AuNPs in suspensions, Beer–Lambert law, or Mie theory by internal reflection due to optical diffraction in 16 nm AuNP–PDMS films and Mie scattering in 76 nm AuNP–PDMS films. Resonant extinction per AuNP for 16 nm AuNPs with negligible resonant Mie scattering was enhanced up to 1.5-fold at interparticle separation (i.e., Wigner–Seitz radii) comparable to incident wavelength. It was attributable to diffraction through apertures formed by overlapping electric fields of adjacent, resonantly excited AuNPs at Wigner–Seitz radii equal to or less than incident wavelengths. Resonant extinction per AuNP for strongly Mie scattering 76 nm AuNPs was enhanced up to 1.3-fold at Wigner–Seitz radii four or more times greater than incident wavelength. Enhanced light trapping from diffraction and/or scattering is relevant to optoelectronic, biomedical, and catalytic activity of substrates embedded with NPs.

The influence of different electrolytes on the electrical and optical properties of polymer films electrochemically synthesized from 3-alkylthiophenes

In this study, we observed significant differences in the electrical and optical properties of polymer films electrochemically synthesized from two 3-alkylthiophene monomers on platinum wires in 0.100 mol L−1 LiClO4/acetonitrile (ACN) or Et4NBF4/ACN, when compared to the following homopolymer films: poly(3-methylthiophene) (P3MT), poly(3-hexylthiophene) (P3HT) and poly(3-octylthiophene) (P3OT), prepared under the same conditions. Electrical impedance spectroscopy was used to assess the resistive and capacitive properties of the polymer films [P3MT and P3HT—CP3(MT-HT); P3MT and P3OT—CP3(MT-OT); P3HT and P3OT—CP3(HT-OT)] at overpotentials determined beforehand by Cyclic Voltammetry. The films synthesized in LiClO4/ACN with the lowest charge transfer resistance values were CP3(MT-HT) and CP3(MT-OT), and synthesized in Et4NBF4/ACN, CP3(HT-OT). In terms of their optical properties, the films synthesized in LiClO4/ACN exhibited hypsochromic shift of E g values and a drop in electron affinity values by comparison with homopolymer films and those synthesized in Et4NBF4/ACN. Based on Photoluminescence (PL) Spectroscopy it was possible to identify the contributions of the quinone and aromatic segments characteristic of homopolymers in the films synthesized in Et4NBF4/ACN. For the films synthesized in LiClO4/ACN, it was not possible to perform the same comparison because there was a discrepancy between the bands observed in the PL images of these materials and those of the homopolymers, suggesting the formation of not only blend structures but also copolymer films. Using Raman Spectroscopy it was possible to identify aromatic, radical cation and dication segments and verify the higher stabilization of radical cation and dication segments in resistive films. It was also possible to observe changes in the morphological structures of the films by comparison with the homopolymers, in addition to alterations due to changes in electrolyte during synthesis using scanning electron microscopy.

Angle dependent optical properties of polymer films with a biomimetic anti-reflecting surface replicated from cylindrical and tapered nanoporous alumina

Anodic porous alumina nanostructures have been fabricated with tapered and cylindrical pores with a spacing of 100 and 200 nm and depth of 180–500 nm. The porous nanostructures were replicated into polymer films to create a moth-eye anti-reflecting surface by a roll-to-roll UV replication process. The angle dependent optical transmission of the resulting polymer films exhibited up to a 2% increase in transmission at a normal angle and up to a 5% increase in transmission at a 70° angle of incidence to an equivalent film with a surface replicated from polished aluminum. No significant difference was observed between the optical performance of moth-eye surfaces formed from cylindrical and tapered nano-pores.

ENHANCED OPTICAL THIRD HARMONIC GENERATION IN THICK ORGANIC FILMS

In order to enhance optical third-harmonic generation (THG) in polymer films, we investigated linear and nonlinear optical properties of polymer films containing ethyl-violet with varying thickness. The THG intensity increased monotonically with thickness, as opposed to the theory for non-phase-matched THG in films thicker than the coherence length. By measuring the refractive indices, we found that the difference between the indices of the fundamental and the third-harmonic was smaller in thicker films. Thus, the coherence lengths for thicker films were evaluated to be larger than those for the thin films, explaining the monotonic increase of the THG signal with thickness.

Optical properties of polymer films with embedded single‐wall carbon nanotubes

AbstractIn this work the thin polymer films (based on polyvinyl alcohol or carboxymetylcellulose) containing single‐wall carbon nanotubes synthesized by different methods have been fabricated by a novel technology and studied in detail by UV–VIS–NIR optical absorption and Raman scattering techniques. The films are prospective as an optical material with a high non‐linearity. This property allows using them as ultra‐fast saturable absorbers in different laser schemes, especially, in fiber lasers. The optical spectroscopy has been used for optimization of several film parameters: an optical density, a thickness, a level of scattered light and proximity of the film absorption bands to the operation wavelengths of different solid state lasers. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Optical properties of polymer films for transparent insulation

Commercially available, highly transparent polymer films for transparent insulation applications were investigated systematically as to their relevant optical properties in the solar and infrared wavelength range. The photometric characterisation in the solar range and the calculation of non-spectral, solar optical film properties using models for scatteringabsorbing media have shown, that the solar extinction is dominated by scattering occuring mainly at the surface. For various amorphous and semicrystalline films the root-mean-square surface roughness correlated well with the solar optical thickness. Regarding high infrared absorptance in the wavelength range of about 10 μm the carbon-oxygen single bond is highly effective for commercial materials with maximum service temperatures of about 100 °C. For 50 μm thick films of different polymer types with carbon-oxygen single bonds in the molecular structure a good correlation between the concentration of the functional corbon-oxygen group and the non-spectral, infrared optical thickness was found.

Field-responsive chiral-photochromic side-chain liquid-crystalline polymers

A series of cholesteric copolymers containing combined chiral-photochromic side-groups has been obtained and their phase behaviour, optical and photo-optical properties have been studied. All copolymers are characterized by selective light reflection in the visible and IR spectral regions. It is shown that the light can be used as a very effective regulated 'external field' to control locally supramolecular structure and the optical properties of polymer films. The synthesized polymers are shown to be promising candidates for colour data recording.

Water-soluble chromophore containing copolymers for bottom antireflection coating applications in lithography

Regulatory concerns in the semiconductor industry from both VOC emissions and solvent handling have prompted the desire to introduce water-based formulations in spin-coating fabrication processes. As resolution demands for i-line lithography are driven to finer feature size and architecture, the need for antireflection coatings as a means of eliminating feature distortions from back reflected light is increasing. Common image irregularities, such as reflective notching and standing wave effects, can be effectively eliminated through application of an antireflection coating of optimal thickness between the resist layer and substrate. This work describes the design and development of novel side-chain methacrylate copolymers for use in water-based antireflection coating formulations. A pendant chromophore is incorporated into the polymer structure to allow optimization of the critical coating optical properties, refractive index, and absorption coefficient. The polymer solubility parameter and crosslinking density can be tailored by incorporation of appropriate functionality to allow compatibility with the device fabrication process. Terpolymers were designed, which were water-soluble, had a thermally activated crosslinking mechanism, and contained a keto-ester azobenzene chromophore that was highly absorbing at i-line wavelength. Optical properties of polymer films were collected by spectroscopic elipsometry and utilized in the design process to identify the optimum chromophore structure. Lithographic images, fabricated utilizing these coatings, were of excellent quality, allowing critical dimension resolutions of less than 0.3 µm. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1304–1316, 1999

Effects of ion bombardment on polymer films

With an increase in the use of polymers for aerospace applications, the degradation of polymers in space is receiving more attention. In this paper, we studied the influences of ionic impact on the surface polymers of spacecraft. The effects of ion bombardment on the chemical structures and optical properties of polymer films were investigated. The specimens were polyimide and teflon films. Oxygen and nitrogen ion beams with energies in the range of 0.5–1.0 keV and doses between 1.7 × 10 15 and 8.2×10 16 ions cm −2 were exposed to the polymers. In-situ X-ray photoelectron spectroscopy (XPS) and spectral transmittance analyses were carried out on the polymers before and after ion bombardment. The in-situ XPS analyses showed that the addition reactions of oxygen and nitrogen atoms and desorption of components caused changes of chemical structures in the ion-bombarded polymers. The in-situ spectral analyses showed that the spectral transmittances were decreased by the ion bombardment.

Characterisation of the optical properties of thin polymer films for their application in detection of volatile organic compounds

The interaction of polymers with volatile organic compounds is widely used in sensor applications. Interaction with an analyte changes the optical properties of polymer films. We investigated two commercially available (poly)siloxanes and one (poly)urethane in contact with tetrachloroethene, toluene and cyclohexane vapours. The refractive index of the polymers and the changes in the physical thickness are separately determined by spectroscopic ellipsometry. The information obtained is used to optimise the sensitive layers with respect to sensitivity and selectivity. With the information obtained the most selective polymers can be chosen for every application.

Nonlinear optical properties of epoxy/acryl semi-IPN

Effects of IPN (Interpenetrating Polymer Network) structures on the nonlinear optical properties of the polymers were studied. The IPN's were prepared using simultaneous polymerization, spin coating and post curing. The second order nonlinear optical properties of polymer films were evaluated by Maker-fringe experiment using the facilities in IBM research center at Almaden. The noncentrosymmetric structure for second order optical nonlinearity was obtained by applying an electric field using corona poling. The d33 values of epoxy,semi-IPN(50/50) and acrylic resin were 12.2 pm/V, 4.2 pm/V and 0.9 pm/V respectively. Semi-IPN had good stability after initial decay.

Semiconductor-Doped Polymers. Linear and Nonlinear Optical Properties.

ABSTRACTSemiconductor clusters with sizes of a few to hundreds of Å, covering the entire range from molecular to bulk, have been prepared within polymer films. For PbS, the band-gap shifts to higher energy as the cluster size decreases and eventually converges to the transition energy of the first excited state of PbS molecule. The observed dependence of band-gap on cluster size can be explained by a tightbinding model that takes into account the effects of band nonparabolicity. These semiconductor-doped polymers represent a new class of nonlinear optical materials. Here we present the nonlinear optical properties of polymer films doped with 50 A CdS and discuss the possible mechanisms.

Preparation and optical properties of polymer films having lamellar structure and cylindrical air bubbles

AbstractPolymer films displaying lustrous, iridescent colors were obtained by irradiation of poly(methyl methacrylate) films containing 1,4‐benzoquinone with a medium pressure mercury lamp followed by solvent treatment. The colors were not produced by visible light‐absorbing species in the polymer films because the color seen in reflection was complementary to that seen in transmission.It was found from optical and scanning electron microscopic studies of the polymer films that they have two characteristic optical structures; a great number of microcylindrical air bubbles oriented perpendicularly to the film surface and periodic lamellas with planes parallel to the film surface. The colors of the polymer films were thought to be produced by this periodic lamellar structure which would act as a three dimensional optical reflection grating. Continuous color change on tilting the sample could also be explained by the Bragg equation.

Some optical properties of polymer films prepared by glow discharge polymerization from methane, tetramethylsilane, and tetramethytin

Some optical properties of polymer films prepared by glow discharge polymerization from methane, tetramethylsilane, and tetramethytin