Thin films, biomedical applications

Figure 12.30 Potential uses of polyphosphazenes (a) A thin film of a poly(aminophosphazene) sueh materials are of interest for biomedical applications, (b) Fibres of poly[bis(trifluoroethoxy)phosphazene] these fibres are water-repellant, resistant to hydrolysis or strong sunlight, and do not burn, (c) Cotton cloth treated with a poly(fluoroalkoxyphosphazene) showing the water repellaney eonferred by the phosphazene. (d) Polyphosphazene elastomers are now being manufaetured for use in fuel lines, gaskets, O-rings, shock absorbers, and carburettor eomponents they are impervious to oils and fuels, do not bum, and remain flexible at very low temperatures. Photographs by eourtesy of H. R. Allcock (Pennsylvania State University) and the Firestone Tire and Rubber Company.

In the last several years, polymer thin film deposition using chemical vapor deposition (CVD) has become increasingly popular. CVD of polymers offers numerous unique advantages over other polymer synthesis techniques and has been exploited for a multitude of applications in microelectronics, optical devices, biomedical industry, corrosion resistant and protective coatings, and even in the automobile industry. CVD of polymers (also referred to as chemical vapor polymerization, CVP, or sometimes Vapor Deposition Polymerization, VDP) differs from inorganic CVD (such as for metallic or ceramic thin films) and must be developed and optimized... 

Thus, we can conclude that the method reported here is a convenient one for grafting chemically thin polymer films onto oxidized metal surfaces. The grafted polymer films can then be further functionalized for various technological or biomedical applications. 

Nanoscale materials are those with dimensions less than 100 nm. Most of the nanomaterials used, such as oxides, sulfides, nitrides, and others are well known, in many cases since the beginning of civilization. In recent decades, it has been observed that specific properties of these materials, useful in biomedical, electromagnetic, mechanical, and catalytic areas," can be enhanced by reducing particle size to nanoscale dimensions. Many synthetic strategies have been developed in order to obtain nanometric materials with specific properties. Thin films of powders, in particular, have been the subject of current investigations. Studies of new synthetic approaches for nanometric films are intimately connected with the development of the chemical vapor deposition technique, which has widespread acceptance and is used for the production of important supplies for semiconductor electronic applications. ... 

For the electronics and biomedical applications, the galvanic displacement deposition can be successful when very thin films are required and when an appropriate surface pretreatment is carried out to achieve a good adhesion of the deposited metallic film. 

In the biomedical applications outlined by Ward et al. (7 ), more so than in any other separation application of synthetic polymeric membranes, the goal is to mimic natural membranes. Similarly, the development of liquid membranes and biofunctional membranes represent attempts by man to imitate nature. Liquid membranes were first proposed for liquid separation applications by Li (46-48). These liquid membranes were comprised of a thin liquid film stabilized by a surfactant in an emulsion-type mixture. Wtille these membranes never attained widespread commercial success, the concept did lead to immobilized or supported liquid membranes. In... 

We believe that the low viscosity of CO2, coupled with its excellent wetting properties, will enable whole new classes of thin-film coating operations that will at the same time be environmentally responsible. These are likely to be important, not just for microelectronics applications but also for biomedical and nanotechnology formulations. Even though there are still many technical and economic barriers to the total acceptance of these technologies, we believe that environmental pressures as well as technical requirements for pure component systems with high uniformity will over time help dry" C02-based processes play an increasingly important role in industrial environments. 

Morphology control is indispensable in many of the advanced applications envisioned for functional mesoporous materials (54, 267). Permselective membranes, micro-spheres, or monoliths are important for sorption, separation, and chromatography purposes. Porous thin films or fibrous structures are relevant for electronics, optics, low fe-dielectrics, and sensing applications. Colloidal particles or nanospheres are preferred for biomedical systems to be used in drug delivery or magnetic resonance imaging (MRl) with contrast agents. 

CPs can be fabricated through a variety of routes which are classified as either predominantly electrochemical or chemical. While electrochemical synthesis has been more widely used for preparing nanoscale CP thin films for biomedical applications, chemical polymerization can produce large quantities of CP thick films or colloidal dispersions at low cost. Despite these advantages, chemical techniques have found relatively little application in biomedical applications. The advantages and disadvantages of electrodeposition and chemical synthesis are summarized in Table 18.2. 

Thin film coatings for biomaterials and biomedical applications... 

Thin Film Coatings for Biomaterials and Biomedical Applications. http //dx.doi.org/10.1016/B978-l-78242-453-6.00001 8 Copyright 2016 Elsevier Ltd. All rights reserved. 

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