A novel photobleachable polysilane copolymer for optical waveguide fabrication

Poly(methylphenylsilane)‐poly(benzylmethacrylate) (PMPS‐PBzMA) block copolymer was prepared by photopolymerization of benzylmethacrylate (BzMA) monomer using PMPS as a macromolecular photo‐radical initiator. Its application as a photobleachable polymer material for optical waveguide fabrication was investigated. By changing weight ratios of BzMA to PMPS during polymerization, the obtained PMPS‐PBzMA showed different photo‐induced refractive changes. PMPS‐PBzMA proved to have good photosensitivity, optical properties, and thermal stability. A multimode PMPS‐PBzMA optical waveguide was achieved, with a propagation loss of 1.0 dB/cm at 1310 nm. Copyright © 2009 John Wiley & Sons, Ltd.     

Modeling of substrate-induced anisotropy in through-plane thermal behavior of polymeric thin films

Polymeric thin films are widely used in microelectronic applications for a variety of purposes. These films may possess completely isotropic material properties and yet still exhibit anisotropic effects due to the constraining influence of the substrate coupling into the film behavior via the film Poisson ratio. A theoretical model of this effect on the through-plane thermal properties of isotropic thin films for single layer (thin film rigidly clamped) and bilayer (thin film on substrate, e.g., silicon wafer) has been developed based on the assumption that the material follows Hooke's law in all directions. Finite element analyses using ANSYS 5.0A have also been performed to confirm theoretical results both for single-layer and bilayer models. In the case of Poisson ratio of 0.5, the effective coefficient of thermal expansion (CTE) in the thickness direction can be as high as three times that of the unconstrained film. © 1996 John Wiley & Sons, Inc.     

Synthesis of crosslinkable fluorinated polyesters for optical waveguide devices

A series of novel crosslinkable, highly fluorinated polyesters were synthesized by copolycondensation reactions of terephthaloyl chloride with 4, 4′‐(hexafluoroisopropy‐lidene)‐diphenol and 2,2,3,3,4,4,5,5,6,6,7,7‐dodecafluoro‐octane‐1,8‐diol, followed by reaction with 2‐hydroxyethyl methacrylate. The resulting polyesters with the molecular weights (M_n: 12,100–20,000 g mol^?1) and polydispersities (1.49–2.25) were useful for the fabrication of polymer optical devices because of their good solubility in common organic solvent and the processable flexibility. The ratios of the components of the polyesters were characterized by FTIR and NMR. The polyesters had high glass transition temperature (T_g,: up to 170 °C) and good thermal stabilities (T_d: up to 470 °C). The refractive index of the polyester film was tuned and controlled in the range of 1.447–1.576 at 1550 nm by monitoring the component fractions during the preparation procedures. Low‐loss optical waveguides were fabricated from the resulting polyesters and the propagation loss of the channel waveguides was measured to be around 0.56 dB/cm at 1550 nm. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5923–5931, 2007     

Quantitative characterization of optical anisotropy in high refractive index films

Waveguide coupling measurements of polymers have largely concentrated on the application of mode analysis to the study of thin supported films (such as spin coatings). The use of prism coupling to study thick, freestanding polymer films, however, has not been reported. In this paper, the ability of prism coupling to characterize the three-dimensional optical properties of thick, freestanding polymer films and sheets is demonstrated. A modified prism coupling procedure is described that allows the determination of all three principal refractive indices in thick, three-dimensionally anisotropic freestanding films. A Metricon prism coupler is used in a manner similar to an Abbé refractometer for the measurement of isotactic polypropylene, poly(ethylene terephthalate), PMDA-ODA polyimide, and poly(phenylene sulfide). Three series of PMDA-ODA films are also investigated in this study. The first series has been drawn to different extensions from three-dimensionally random films. The second series has random orientation in the plane of the film but different degrees of planarity with respect to the through direction. The third series are commercial films of varying thickness. These three series of films are compared as to the optical an-isotropy that is developed from the three different fabrication processes. © 1993 John Wiley & Sons, Inc.     

Thin films of peroxopolytungstic acids: applications to optical waveguide components

Thin films of peroxohetero(carbon)polytungstic acid (CW-HPA) and carbon-free isopolytungstic acid (W-IPA) were prepared, and examined in terms of optical and etching properties. Thermal decomposition was found to give good results in removing excess hydrogen peroxide (H₂O₂) during the preparation of CW-HPA and W-IPA. It was shown for the first time that thin films of CW-HPA and W-IPA have very high refractive indices (larger than 2.0) when sufficiently dried. Optical waveguide (OWG) characteristics of these films were examined using a slab-type OWG structure and ARROW (Antiresonance Reflection Optical Waveguide)-type structures. An embossing technique was applied to make diffractional grating couplers.     

Refractive index‐modulated grating in two‐mode planar polymeric waveguide produced by two‐photon polymerization

A polymeric waveguide film was manufactured by spinning the materials on quartz substrate. Two‐photon‐initiated photopolymerization was carried out by tight‐focusing femtosecond laser pulses in the two‐mode planar waveguide. A typical index‐modulated grating of 2.5 × 2 mm areas without morphology was fabricated. The results show that peak‐to‐peak modulation depth of the surface profile of grating region was only about 7 nm. The diffraction efficiency (DE) of the grating with a spacing period 2 µm was 0.17% and the corresponding index modulation reached 5.7 × 10^?3. Copyright © 2007 John Wiley & Sons, Ltd.     

光波导乙醇气体传感器的研究

以聚偏氟乙烯(PVDF)作为敏感试剂固定在钾(K⁺)离子交换玻璃光波导表面,研制了光波导乙醇气体传感器.该传感器具有可逆性好、灵敏度高、响应速度快、选择性和重现性好、能在室温操作等特点.     

Optical,mechanical, and photoelastic anisotropy of biaxially stretched polyethylene terephthalate films studied using transmission ellipsometer equipped with strain camera and stress gauge

The anisotropic properties of polyethylene terephthalate film resulting from its manufacturing process are quantitatively investigated in terms of its optical, mechanical, and photoelastic aspects. Transmission ellipsometers and a Jones‐matrix‐based analysis software together with a 4 × 4 Berreman‐matrix‐based analysis software are adopted to determine the wavelength‐dependent in‐plane birefringence, the principal refractive indices, and the orientation of the optical axis. Mechanical anisotropy is characterized in terms of the elastic compliance tensor components using the measured azimuthal angle‐dependent Young's modulus and Poisson's ratio. From the measured variation of the wavelength‐dependent in‐plane birefringence as a function of tensile stress, the dispersive photoelastic coefficients are obtained for a few sample azimuthal angles, and the components of the photoelastic tensor are determined. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 152–160     

Error minimization in the envelope method for the determination of optical constants of a thin film

The algorithm for the determination of optical constants of a weakly absorbing thin film from the envelope method has been modified to minimize the error in the estimated values of extinction coefficient (k) as a function of wavelength. The refinement procedure is based on an extension of interference order adjustment method used for improving the estimated values of film thickness d and wavelength‐dependent refractive index n from the envelope method. The proposed modification when applied to a hypothetical as well as an experimental film is found to work well over a wide spectral region. Copyright © 2010 John Wiley & Sons, Ltd.     

Electrical and Optical Properties of MgO Thin Film Prepared by Sol-Gel Technique

MgO thin films with either (111) or (200) preferential orientation have been prepared on (100) Si substrates by sol-gel method after a heat-treatment at 800°C. The obtained (111) preferentially oriented MgO film has a dielectric constant of 7.0 with a loss factor of 5% and a dielectric strength higher than 8 × 10⁵ V/cm. The optical refractive index, which depends on the film thickness, is 1.71 when the film thickness is 260 nm. The surface structure of the Si substrate is believed to affect the preferential orientation of the sol-gel derived MgO film. Specifically, the microstructures at the interface indicate an interdiffusion of Mg, O, and Si between the film and the substrate.     

Photonic electric field sensor based on polymeric microspheres

The detection of electric field by monitoring the optical whispering gallery mode shifts of polymeric microspheres is demonstrated. Two types of spheres are considered; (i) a polydimethylsiloxane (PDMS) sphere with 60 parts base silicon elastomer-to-1 part polymer curing agent by volume and; (ii) a silica sphere coated with a PDMS (uncured) base. The optical mode shifts are caused by perturbations to the resonator morphology induced by electrostriction effect in the presence of an external electric field. Preliminary experiments show that the latter microsphere yields higher sensitivity (0.027 pm/V m⁻¹) with a measurement precision of ∼1.8 V/m. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 276–279     

刚果红交联聚乙烯醇薄膜／K^＋交换玻璃光波导检测氯化氢气体

用环氧氯丙烷为交联剂合成了刚果红(CR)交联聚乙烯醇(PVA)CR-PVA敏感试剂.用匀胶机将其做成薄膜固定在钾离子交换玻璃光波导表面,研制出一种光波导氯化氢气体传感器.CR-PVA薄膜碱式结构的最大吸收波长在600 nm以下,对波长为632.8 nm的激光吸收很弱;薄膜与酸性气体发生反应后强烈吸收波长在632.8 nm附近的导波或消失波;检测输出光强度的变化,即能够测出酸性气体浓度.测试结果表明,本传感器对低浓度HCl气体有快速响应,且对1.6～192 mg/m3范围内有良好的线性响应;SO2、NO2气体的浓度大于18000 mg/m3时才有响应,而对于高、低浓度H2S气体均无响应.     

Structure and electrical properties of undoped oriented poly(phenylene vinylene) films

The influence of anisotropic structure on the electrical properties of undoped oriented poly(phenylene vinylene) (PPV) films was investigated with impedance spectroscopy and structural characterization. The oriented structure of the stretched PPV films was studied with wave-guide coupling and infrared dichroism. It was found that the unstretched PPV film had a highly planar structure, and one-way stretching converted the planar structure into a uniaxial structure. The impedance of undoped PPV thin films was measured along three different directions: through the film thickness direction, parallel to the stretch direction in the film plane, and perpendicular to the stretch direction in the film plane. Two relaxations were observed, one corresponding to the bulk behavior in the high-frequency range and the other to an interfacial contact polarization in the low-frequency range. From equivalent circuit modeling, it was found that the bulk conductivity through the film thickness direction decreased with increasing orientation, whereas the high-frequency dielectric constant through the film direction remained constant. In addition, the conductivities measured in the film plane were at least two orders of magnitude higher than the conductivity in the direction normal to the film surface. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 98–116, 2004     

Study on Combined Optical and Electrochemical Analysis Using Indium‐tin‐oxide‐coated Optical Fiber Sensor

In this work an optical fiber sensor, where a lossy‐mode resonance (LMR) effect was obtained due to indium tin oxide (ITO) thin overlay, has been simultaneously applied as a working electrode in a 3‐electrode cyclic voltammetry electrochemical setup. Since LMR conditions highly depend on refractive index of a surrounding medium, an LMR‐based sensor was applied for optical investigations of electrolyte's properties at the ITO surface. We have found that the optical response of the sensor highly depends on the applied potential and its changes, as well as the properties of the investigated electrolyte, i. e., its composition and presence of a redox probe. Both optical and electrochemical response of the ITO‐LMR sensor to various concentrations of phosphate‐buffered saline (PBS), NaCl and Na₂SO₄, as well as scan rate were investigated and discussed. We have found that the responses in optical and electrical domains differ significantly and may deliver supplementary information about the investigated analyte.     

The influence of hydrogen chloride doping level on the complex refractive indices of anisotropic polyaniline film: Application of a new internal reflection waveguide coupling technique

Nondestructive three‐dimensional refractive‐index measurements are used for the determination of both crystallinity and orientation in thin polymer films. The prism waveguide coupler is particularly suitable for three‐dimensional isotropic and anisotropic thin‐film studies because of the quantitative character of the information obtained and the ease of data acquisition. It has been limited, however, to measuring the refractive index of optically transparent or weakly absorbing films. This study shows that a modified prism waveguide coupler can be used to determine the complex refractive index over a range from transparent to highly absorbing films from the internally reflected light intensity. Thus, both the refractive index, n, and the extinction coefficient, k, can be obtained. This method is used to determine the anisotropic three‐dimensional n and k values of spin‐coated emeraldine base and hydrogen chloride doped emeraldine salt polyaniline films. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2481–2490, 2001     

Selective detection of gas-phase TNT by integrated optical waveguide spectrometry using molecularly imprinted sol-gel sensing films

A chemical sensor was developed to detect the explosive 2,4,6-trinitrotoluene (TNT) utilizing planar integrated optical waveguide (IOW) attenuated total reflection spectrometry. Submicron thick films of organically modified sol-gel polymers were deposited on the waveguide surface as the sensing layer. Sol-gels were molecularly imprinted for TNT using covalently bound template molecules linked to the matrix through 1 or 2 carbamate linkages. Upon chemical cleavage of the template and displacement of the TNT-like pendant groups from the matrix, shape-selective binding sites were created that possess a primary amine group. The amine was used to deprotonate bound TNT yielding an anionic form that absorbs visible light. Binding of TNT and subsequent conversion to the anion results in the attenuation of light propagating through the waveguide, thus creating a spectrophotometric device. Sensitivity can be achieved by taking advantage of the substantial pathlength provided by the use of single mode IOWs. The limit-of-detection to gas-phase TNT was found to be five parts-per-billion (ppbV) in ambient air at a flow rate of 40 mL min⁻¹ given a 60 s sampling time. The sensor is highly selective for TNT due to the selectivity of binding site recognition of TNT and the subsequent generation of the TNT anion. Response to TNT is not reversible which results in an integrating sensor device which, in theory, can improve the ability to detect small amounts of the explosive if the exposure time is sufficient in length.     

Rational design of polyhedral oligomeric silsesquioxane fillers for simultaneous improvements of thermomechanical properties and lowering refractive indices of polymer films

We describe here the design and synthesis of the polyhedral oligomeric silsesquioxane (POSS)‐based dual‐functional molecular fillers for simultaneously lowering refractive indices and improving thermomechanical properties of conventional polymers. We prepared the composite films with poly(methyl methacrylate) and polystyrene containing the series of the POSS derivatives with the single functional unit for interacting with polymer chains and heptacyclopentyl substituents for creating exclusive volumes around the POSS core. From the measurements of refractive indices of polymer composites, it was revealed that all POSS fillers can lower the refractive index of the films. In addition, thermal stabilities and mechanical properties were enhanced by adding POSS fillers. The filler effect on the thermal properties can be explained by the structural features of POSS: The highly symmetrical structure of the silica cube should suppress thermal motions, resulting in the large enhancement of thermomechanical properties of polymer matrices. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3583–3589     

Functional polymers for colloidal applications. V. Novel behavior of polymeric emulsifiers in emulsion polymerization

The polymeric emulsifier poly(dodecyl acrylate-co-acrylic acid) [i.e., the sodium salt (PDA)] and monomeric emulsifier sodium dodecyl glutarate (SDG) have been synthesized. PDA and SDG are used as emulsifiers in the emulsion polymerization of styrene with both the water-soluble initiator potassium persulfate (K₂S₂O₈) and the oil-soluble initiator 2,2′-azobisisobutyronitrile (AIBN). The PDA/K₂S₂O₈ system showed a bimodel distribution of particle sizes (2 and 0.05 μm). A bimodel particle distribution was also found for the PDA/AIBN system, but the distribution for the large particles was wide (0.1–10 and 0.07 μm). The SDG/K₂S₂O₈ system displayed only one kind of particle size (0.05 μm), but the SDG/AIBN system also showed a bimodel distribution of particle sizes (0.05 and 5 μm). These bimodel distribution results for the PDA/K₂S₂O₈, PDA/AIBN, and SDG/AIBN systems indicate that the polymerization sites are both in oil droplets and in micelles (polymer aggregates). This mechanism is interpreted in terms of the formation of polymer aggregates, which is supported by the results of pyrene solubilization, pyrene fluorescence, surface tension, and pyrene excimer experiments. © 1993 John Wiley & Sons, Inc.     

DSC studies of solid polymeric electrolytes

Relations are demonstrated between the conductivity, phase structure and thermal history of some solid polymeric electrolytes. The results obtained for systems based on commercially available polymers, e.g. (ethylene oxide), and for specially synthesized materials are presented. Special emphasis is placed on the correlation between the crystallinity, glass transition temperature, melting temperature and conduction properties of the polymeric electrolytes.This work was supported financially by the Rector of Warsaw University of Technology according to research program 503/164/220/1.     

Synthesis and characterization of hyperbranched‐poly(siloxysilane)‐based polymeric photoinitiators

Three UV‐sensitive, hyperbranched‐poly(siloxysilane)‐based polymeric photoinitiators, bearing an alkyl phenone moiety linked to the surface of the hyperbranched polymer, were synthesized via the hydrosilylation of hyperbranched poly(siloxysilane) and modified UV‐sensitive compounds. Hyperbranched poly(siloxysilane) was prepared via the polyhydrosilylation of the AB₂‐type monomer methylvinyldichlorosilane. The chemical structures of the polymeric photoinitiators were characterized with ¹H, ¹³C, and ²⁹Si NMR, elemental analysis, Fourier transform infrared, differential scanning calorimetry, UV spectrophotometry, and thermogravimetric analysis. The UV‐curing behaviors of the blends of the hyperbranched polymeric photoinitiators with UV‐curable epoxy acrylate (EA) resin were determined by Fourier transform infrared, and the results showed that the initiation efficiency of the polymeric photoinitiators was excellent and that the thermostability of the EA/polymeric photoinitiator curing systems was higher than that of the EA/photoinitiators. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3261–3270, 2006