Optical fibers polymer coatings

GTP is a safe operation. A runaway polymerization can be quickly quenched with a protonic solvent. Since the group transfer polymerization goes to completion, no unwanted toxic monomer remains the silicone group on the living end after hydroxylation is removed as inactive siloxane. The living polymer in GTP is costlier than traditional polymerization techniques because of the stringent reaction conditions and requirements for pure and dry monomers and solvents. It can be used in fabrication of silicon chips, coating of optical fibers, etc. 

Volkan M., Stokes D.L., Vo-Dihn T., Surface-enhanced Raman of dopamine and neurotransmitters using sol-gel substrates and polymer-coated fiber-optic probes, Appl. Spectrosc. 2000 54 1842-1848. 

In order to act as a transducer optode must be attached to the optical fiber. Bulks (>1 mm) of sol-gel matrix can be easily glued to the fiber tip, especially, if the polymer fiber is used39. The smaller optodes can be attached to fiber end by dip-coating method or simply by direct painting of the fiber-tip with a liquid gel. 

Traditionally, UV curable polymers have been utilized as coatings for wood and vinyl floors, but their applications have increased dramatically over the last twenty years to encompass many diverse areas, including optical fiber coatings (7), adhesives (2), disc replications (3-5), and microelectronics (6). This widespread use of UV cross-linked systems is attributed to their rapid, energy efficient curing and their solvent free, one piece formulations. Typically, UV curable systems require only a small fraction of the power normally utilized in thermally cured systems and their solvent free nature offers an environmentally safer alternative. 

Poly(2-hydroxyethyl methylmethacrylate) (PHEMA) has been used as a matrix for the detection of metal ions. 79 A near-IR dye (2,3-naphthalocyanine-tetrasulphonic acid) was immobilized in a polymer matrix which was attached to the reaction phase of two optical fibers. A mixture of the matrix and the dye was prepared by mixing PHEMA and dye in a 60/40 ratio. The optimum ratio of polymer and dye were not fully investigated. The dye/polymer mixture was applied to the tip of the probe in 10-to 15-/iL aliquots forming a thin coating on the probe after solvent evaporation as shown in Figure 7.9. 

The opacity of plastic foams, and polymers with scratched surfaces, is also governed by Fresnel s law. The n value of the gas which occupies the scratch indentation is much lower than that of the polymer. Light may be directed through rods of transparent polymers, such as PMMA. This effect may be enhanced when the rod or filament is coated with a polymer with a different refractive index, such as polytetrafluoroethylene (ptfe). Optical fibers utilize this principle. 

A flexible optical fiber has a high-refractive-index, transparent core enclosed in a lower-refractive-index, transparent cladding (Figure 20-18a). The cladding is enclosed in a protective plastic jacket. The core and the coating can be made from glass or polymer. 

Pannell and coworkers34 described the use of poly(ferrocenylsilanes) as coatings in optical fiber gas sensors. In these devices a small change in refractive index of the polymer film results in a large change in the optical transmission of a tapered optical fiber. This is useful for remote sensing of ammonia or carbon dioxide. Polymers of type 6.20 with R/R = Me/Ph and copolymers from monomers with R/R = Me/Ph and Me/Me were found to be effective for this application. 

In 1987 he was promoted to distinguished member of the technical staff and technical manager. His efforts broadened to include projects on polymer-surface interactions adhesion promotion corrosion protection chemical vapor deposition and thin film growth optical fiber coating synthesis, structure, and reactivity of model organic surfaces and time-resolved surface vibrational spectroscopy. 

The great value of the unique characteristics of fluorinated polymers in the development of modern industries has ensured an increasing technological interest since the discovery of the first fluoropolymer, poly(chlorotrifluoro-ethylene) in 1934. Hence, their fields of applications are numerous paints and coatings [10] (for metals [11], wood and leather [12], stone and optical fibers [13, 14]), textile finishings [15], novel elastomers [5, 6, 8], high performance resins, membranes [16, 17], functional materials (for photoresists and optical fibers), biomaterials [18], and thermostable polymers for aerospace. 

BronkKS, Walt DR. Fabrication of patterned sensor arrays with aryl azides on a polymer-coated imaging optical fiber bundle. Analytical Chemistry 1994, 66, 3519-3520. 

Acetylcholineesterase A 350 pM diameter coherent imaging fiber coated on the distal surface with a planar layer of analyte-sensitive polymer that was thin enough not to affect the fiber s imaging capabilities. It was applied to a pH sensor array and an ACh biosensor array (each contain 6000 optical sensor). Fibers were coated with an immobilized layer of poly (hydroxyethylmethacrylate)-N-flurosceinylacrylamide and AChE-fluorescein isothiocyanate isomer poly (acryloamide-co-N-acryl oxysuccinimide), respectively. The response time of the pH sensor was 2 s for a 0.5 unit increase in pH. The biosensor had a detection limit of 35 pM ACh and a linear response in the range 0.1 mM. [90]... 

Solid-phase microextraction (SPME) — is a procedure originally developed for sample preconcentration in gas chromatography (GC). In this procedure a small-diameter fused silica optical fiber, coated with a liquid polymer phase such as poly(dimethylsiloxane), is immersed in an aqueous sample solution. The -> analytes partition into the polymer phase and are then thermally desorbed in the GC injector on the column. The same polymer coating is used as a stationary phase of capillary GC columns. The extraction is a non-exhaustive liquid-liquid extraction with the convenience that the organic phase is attached to the fiber. This fiber is contained in a syringe, which protects it and simplifies introduction of the fiber into a GC injector. Both uncoated and coated fibers with films of different GC stationary phases can be used. SPME can be successfully applied to the analysis of volatile chlorinated organic compounds, such as chlorinated organic solvents and substituted benzenes as well as nonvolatile chlorinated biphenyls. 

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