High oxygen-permeable silicone

Examples of silicones in ophthalmic application have been described.5 1 However, some problems have been reported with the use of silicones in retinal tamponade.542 Silicones are widely used in contact lenses because of their unusually good oxygen permeability and bioinertness, but the need for novel materials continues. Low-modulus fluorosiloxane-based hydrogel lenses with a wide range of water content and high-oxygen permeability have been described in a number of papers.543-... 

PtOEP is widely used as a PSP probe among the metalloporphyrins. The absorption and emission maximum of PtOEP are 381 and 535, and 646 nm, respectively. For examples of PSPs based on the OEP metal complexes in silicone polymer films, PSPs based on the platinum or palladium OEP immobilized in poly(TMSP) film have been reported. Oxygen permeability of poly(l-trimethylsily-l-propyne) (poly(TMSP)) film is about ten times larger than that of poly(dimethylsiloxane) (poly(DMS)) film, and provides a tough and thin film [14,15]. The poly(TMSP) film is a porous polymer matrix with a high oxygen permeability and diffusion, indicating that the probe... 

Fumarate- and fumaramide-containing hydrogels have been prepared with silicone as a co-component that are highly oxygen permeable. These agents are biocompatible and useful as biomedical devices, particularly as contact lenses. 

In addition to these materials, several others, such as polyurethanes, polysulfones, polyvinyl alcohol, and various copolymers, have been tried or are under development. Recently, silicon hydrogel lenses with high oxygen permeability were marketed. The future... 

Silicones are more flexible and of lower strength than polyurethanes. However, they are more chemically stable and are used for artificial finger joints, blood vessels, heart valves, breast implants, outer ears, and chin and nose implants. Silicones have high oxygen permeability and are used for membrane oxygenators and soft contact lenses. ... 

Wang, J. Li, X., Preparation and Characterization of Interpenetrating Polymer Network Silicone Hydrogels with High Oxygen Permeability. J. Appl. Polym. Sci. 2010,116, 2749-2757. 

Silicone Hydrogels. A new class of hydrogels based on silicone has been developed (14). These materials were developed in an attempt to combine the high oxygen permeability of polydimethylsiloxane and the excellent water absorption characteristics of conventional non-silicone hydrogels. This new class of hydrogels was developed primarily for contact lens application. These silicone hydrogels are also prepared by free-radical poljnnerization techniques. 

The high permeability of silicones, particularly polydimethylsiloxane, finds application in extended wear contact lenses where high oxygen permeability is Important. The elastomers are also permeable to a wide variety... 

This paper describes the continued development of oxygen permeable silicone hydrogels based on the [-(CF2)x-H] functionalized siloxanes. A series of methacrylate functionalized fluoro-siloxy silane based monomers were synthesized. These fluorinated monomers, when copolymerized with hydrophilic monomers, such as dimethylacrylamide, resulted in transparent, low modulus hydrogels possessing high levels of oxygen permeability. 

Kunzler et al. (5) prepared silicone hydrogels containing vinyl carbonate end-capped with fluorinated polysiloxanes that had an oxygen permeability of at least about 120 Barters, a water content of at least about 20wt%, and high modulus. 

Recently developed blood oxygenators are disposable, used only once, and can be presterilized and coated with anticoagulant (e.g., heparin) when they are constructed. Normally, membranes with high gas permeabilities, such as silicone rubber membranes, are used. In the case of microporous membranes, which are also used widely, the membrane materials themselves are not gas permeable, but gas-liquid interfaces are formed in the pores of the membrane. The blood does not leak from the pores for at least several hours, due to its surface tension. Composite membranes consisting of microporous polypropylene and silicone rubber have also been developed. 

Many PSPs are composed of probe dyes, such as polycyclic aromatic hydrocarbons (e.g., pyrene) and coordination compounds (e.g., platinum por-phryins and ruthenium(II) polypyridyl complexes) immobilized in various gas permeable polymer films such as silicon polymer, organic glassy polymers (e.g., poly(methylmethacrylate), polystyrene), fluorinated polymers, or cellulose derivatives such as ethyl cellulose [9,10]. As probe molecules interact with polymer matrices directly, the properties of PSPs strongly depend on the properties of polymer matrices. The oxygen permeability of polymer matrix is an especially important factor for highly sensitive PSP. 

Table 9-2 contains values of P for oxygen, nitrogen, carbon dioxide, and water vapor in some polymers (Brandrup and Immergut, 1989). The values of P cover a range of several orders of magnitude between the highly permeable silicone elastomers and the extremely impermeable EVOH materials. As an example, for 02 at 0 °C P = 3.7E-11 cmV Pa1 in polydimethylsiloxane and P = 7.4E-18 cm2s-1Pa-1 in EVOH at 40 % relative humidity(rh). 

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