Polymethyl methacrylate refractive index

Radical copolymerization of diaryl nitrones, such as a-(2-hydroxyphenyl)-A-(2,6-dimethylphenyl) nitrone (HDN), a-(2-hydroxy-4-methacryloyloxyphenyl)-N -(2,6-dimethylphenyl) nitrone (HMDN), and a-(2-hydroxy-4-methacryloyloxy-phenyl)-A-phenylnitrone (HMPN) (Fig. 2.30), with methyl methacrylate leads to copolymers in good yields with considerable quantities of hydroxy substituted diaryl nitrone pendants. The presence of photoactive nitrone pendants in these copolymers allows one to control photochemically the refractive index of polymethyl methacrylate films (468, 700, 701). 

For example, most prototype devices use polymethyl methacrylate CPMMA, trade name PLEXIGLASS) as a substrate material. PMMA has an index of refraction of about 1,49, This produces an escape probability of 26% for isotropic absorption and emission, and an escape probability of 29% for dipole absorption and emission of perpendicularly incident light. 

Hair after treatment with TGA cumene hydroperoxide using methyl methacrylate monomer was hydrolyzed with 5N hydrochloric acid to dissolve away the keratin from the polymer, and part of the resultant fiberlike residue was dissolved in organic solvents. The solute (in the organic solvents) was shown to be polymethyl methacrylate by refractive index and infrared spectroscopy [87]. 

Contact lenses are the most common polymer product in ophthalmology. The basic requirements for this type of materials are (T)excellent optical properties with a refractive index similar to cornea good wettability and oxygen permeability ( ) biologically inert, degradation resistant and not chemically reactive to the transfer area ( ) with certain mechanical strength for intensive processing and stain and precipitation prevention. The common used contact lens material includes poly-P-hydroxy ethyl methacrylate, poly-P-hydroxy ethyl methacrylate-N-vinyl pyrrolidone, poly-P-hydroxy ethyl methacrylate, Poly-P-hydroxy ethyl methacrylate - methyl amyl acrylate and polymethyl methacrylate ester-N-vinyl pyrrolidone, etc. The artificial cornea can be prepared by silicon rubber, poly methyl... 

S. Kang, H. lin, D.E. Day, J.O. Staffer, Optically transparent polymethyl methacrylate composites made with glass fibers of varying refractive index, J. Mater. Res. 12 (1997) 1091-1101. 

Of course, it is impossible to find particles with zero adhesion to confirm the theoretical argument that spheres should form a face-centered cubic structure above 0.49 volume fraction. However, certain types of polymer latex can be made to approximate to the theoretical nonadhesion conditions above. Polymethyl methacrylate particles were polymerized in a dispersion and polymer molecules were grafted to the surface to provide a steep repulsive force on close approach. The solvent was chosen to reduce the van der Waals force to a low level, by matching the refractive index to the spheres, obtaining an almost transparent suspension from the milky preparation. 

Optical composite n. A composite that is transparent or nearly so. Making one requires that the refractive indices of the resin and reinforcing fiber, themselves transparent, be closely equal. This might be feasible with polymethyl methacrylate and a carefully chosen glass, since the refractive index of PMMA ( D °) is 1.49, that of fused quartz is 1.458, and most common glasses are above 1.51. Some... 

Polymethyl methacrylate (PMMA) is a typical transparent amorphous polymer. It has been widely used as an important material in optical devices. It has several advantages, including good flexibility, high strength and excellent dimensional stability however, it suffers from shortcomings such as poor heat resistance, a weak mechanical surface and low refractive index [41, 42]. 

Ion beam-induced chemical modification of polymers, even at low doses, is accompanied by a strong compacting of a polymer host that leads to an increase of the refractive index n [113,114], For instance, in the case of polymethyl methacrylate (PMMA), the relative variation in the refractive index upon ion implantation ranges up to -1-30% [114], which considerably exceeds the changes in the refractive index resulting from ion beam-induced amorphization of a-quartz (A /n = -4%), LaTaOj (An/n = -5%), and other optical materials [114,115]. Moreover, the refractive index of PMMA can be readily controlled because the almost linear An... 

When an amorphous polymer is stretched, the molecules may be preferentially aligned along the stretch direction. In polymethyl methacrylate and polystyrene, such molecular orientation may be detected by optical methods, which measure the small difference between the refractive index in the stretch direction and that in the perpendicular direction. 

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