Plasma methyl methacrylate with

Figure 1. Monomer—copolymer composition relationship for the plasma-initiated copolymerization of methyl methacrylate with styrene. Plasma-initiated polymerization (%) NMR, (x) elemental analysis. Thermal polymerization (O) NMR, (Aj elemental analysis, (—) theoretical curve, tmma = 0.46 =...

Avseenko et al. (2001) immobilized antigens onto aluminum-coated Mylar films by electrospray (ES) deposition. Various surface modifications of the metallized films were studied to determine their abilities to enhance sensitivity. The plastic surfaces were firsf cleaned by plasma discharge treatment, followed by coating with proteins (BSA and casein) or polymers such as poly (methyl methacrylate) or oxidized dextran, or they were exposed to dichlorodimethyl silane to create hydrophobic surfaces. Protein antigen was prepared in 10-fold excess sucrose and sprayed onto the surfaces to form arrays with spot diameters between 7 and 15 pm containing 1 to 4 pg protein. 

In an effort to improve PMMA s photosensitivity further, methyl methacrylate has been copolymerized with higher percentages of the a-keto-oxime methacrylate and terpolymerized with varying amounts of methacrylonitrile. The resulting effects on resist properties, e.g., sensitivity, contrast and resolution, and plasma resistance, are reported here. The terpolymers are up to 85 times more sensitive than PMMA, and retain its high resolution characteristics. 

Monomers Polymerizable by Plasma Initiation. Polymerization data for all of the vinyl monomers utilized in this study are summarized in Table 1. As shown previously, methyl methacrylate is readily polymerizable (, ). Methacrylic acid (MAA) and acrylic acid (AA) are polymerized immediately upon exposure to the plasma. Because the resulting polymers are insoluble in their monomers, the products are precipitated out and conversion is low despite prolonged post-polymerization. However, if water is now added as solvent, polymerization becomes homogeneous and high conversions can be readily achieved with post-polymerization. For example, after a 15 second plasma initiation period more than 80% yield was obtained for a 75% aqueous solution of MAA. The molecular weight, determined by intrinsic viscosity measurements, was found to be 4.5 X 10 gm/mole. 

Several polymethacrylates, primarily alkyl esters, were compared with a novolac resist in terms of etch rates in CF4 and Ar plasmas. The alkyl groups examined included methyl, terf-butyl, cyclohexyl, norbonyl, adamantyl, and benzyl [226]. The polymerization of alicyclic methacrylates was pioneered by Otsu, who has demonstrated facile polymerization of bulky methacrylates and reported high Tg of this class of polymethacrylates [230]. It has been found that alicyclic polymers exhibit better dry etch resistance than acyclic esters and that the dry etch durability is increased by an increase in the number of rings. Thus, poly(adamantyl methacrylate) is as stable as a novolac resist under dry etch conditions. A 30/70 copolymer of adamantyl methacrylate with ter/-butyl... 

Several polymers were evaluated in the form of a surface coating on glass beads packed in columns to determine their ability to retain platelets when whole human blood passes over the surface. This ability was measured as the platelet retention index p, the fraction of platelets retained on the column. Lowest values of p were found for poly(ethylene oxide), polypropylene oxide), poly(tetramethylene oxide) (in the form of polyurethanes), and polydimethylsiloxane. Highest values (around 0.8) were found for cross-linked poly(vinyl alcohol) and the copolymers of ethylenediamine with diisocyanates. Intermediate values were found for polystyrene and its copolymers with methyl acrylate, for polyacrylate, and for poly(methyl methacrylate). The results are interpreted in terms of possible hydrophobic and hydrogen bonding interactions with plasma proteins. 

Lens hazing and protein deposition are common problems for wearers of soft contact lenses. Previous experiments with hydrophobic-hydrophilic copolymers exposed to plasma showed protein adsorption to be minimal at intermediate copolymer compositions. Adsorption of proteins from artificial tear solutions to a series of polymers and copolymers ranging in composition from 100% poly (methyl methacrylate) (PMMA) to 100% poly(2-hydroxyethyl methacrylate) (PH EM A) was measured. The total protein adsorption due to the three major proteins in tear fluid (lysozyme, albumin, and immunoglobulins) was at a minimum value at copolymer compositions containing 50% or less PH EM A. The elution of the adsorbed proteins from these polymers and copolymers with various solutions also was investigated to assess the binding mechanism. 

Non-thermal plasma can be applied not only for the stepwise polymerization discussed earlier, but also for effective stimulation of more conventional chain polymerization processes. Plasma-initiated polymerization of methyl methacrylate (MMA) with production of practically important polymer poly methyl methacrylate (PMMA) is a good example of such... 

Acrylate polymers slowly undergo chain scission upon irradiation with uv light and electron beams. While this property has been used to advantage [acrylic polymers such as poly(methyl methacrylate) have seen use as high resolution but low sensitivity electron beam and DUV resists], in this instance it is undesirable as it compromises plasma etch resistance, and complicates the metrology of acrylate resist patterns when using scanning electron microscopy (112). 

Several workers have proposed new combinations of materials in an attempt to overcome wear. Studies involving polyimides, polyamide-imides, and poly-tetrafluoroethylene-filled polyoxymethylene demonstrated that although wear characteristics were good in dry conditions, the presence of lubricants (blood plasma, water) decreased the wear resistance. Results obtained with reinforcing materials such as carbon fibre and with an aluminium oxide ceramic ball used in conjunction with a polyethylene socket have been presented, Examples of other types of reconstructive surgery involving hard tissue replacement are the use of poly(methyl methacrylate) in chest wall reconstruction and repair of depressed skull fractures, the repair of major crano-orbital defects with the aid of a polyurethane-coated poly(ethylene terephthalate) mesh, and the use of silicone rubber in total finger joint and carpal bone replacement. 

Cemoits and Adhesives.— Information on the role of acrylic bone cements in joint prostheses has already been given (see p. 419). However two related papers are worthy of mention in this more general context. The first discusses the clinical influences on the release of monomer from bone cement" and the second is concerned with the fate of methyl methacrylate in blood." Bayne et al. have primarily concerned themselves with effects associated with the preparation of the methyl methacrylate dough moulding compound immediately prior to use and shown that this does affect the amount of monomer available for release into the blood stream. Rejke et aU on the other hand have used gas-liquid chromatography to study the relative concentrations of methyl methacrylate monomer in cells and plasma as a function of time. 

PEG chains were also grafted to poly(methyl methacrylate) (PMMA) in order to improve the hemocompatibihty of the material. XPS, used in the angle-dependent mode, showed that PMMA tends to be enriched at the surface, except when the PEG side-chains are long and the PEG content is high. The hemocompatibility of these materials, assessed using the recalcification time of platelet-rich plasma, was shown to increase with the PEG concentration at the surface. ... 

Mori, A., Ito, Y., Sisido, M., and Imanishi, Y. (1986) Interaction of polystyrene/poly(gamma-benzyl L-glutamate) and poly(methyl methacrylate)/poly(gamma-benzy 1 L-glutamate) block copolymers with plasma proteins and platelets. 

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