2-Hydroxyethyl methacrylate diffusion

Figure 5 The mutual diffusion coefficient, D, of sodium chloride as a function of reciprocal matrix hydration, H, in various methacrylate gels. HPMA-GMA polyfhydroxypro-pyl methacrylate-co-glyceryl methacrylate) HEMA polyfhydroxyethyl methacrylate) MMA-GMA poly(methyl methacrylate-co-glyceryl methacrylate) HEMA-MMA poly-(hydroxyethyl methacrylate-co-methyl methacrylate) HPMA-MMA polyfhydroxypropyl methacrylate-co-methyl methacrylate) HPMA-GDMA polyfhydroxypropyl methacry-late-co-glyceryl dimethacrylate). (From Ref. 64.)...

JH Kou, GL Amidon, PI Lee. pH dependent swelling and solute diffusion characteristics of poly(hydroxyethyl methacrylate-co-methacrylic acid) hydrogels. Pharm Res 5 592-597, 1988. 

The effect of hydrophobicity of the polymer on the permeability of poly(2-hydroxyethyl methacrylate (HEMA)-co-methacrylic acid (MAAc) hydrogels was studied [12], The hydrophobicity was controlled by copolymerization with butyl methacrylate (BMA). The dependence of permeability on pH increased as the hydrophobicity increased even though the rate of diffusion decreased. Cross-link density of the hydrogel also contributed to pH-dependent permeability. 

Figure 14 The reversibilities of insulin permeation through polymer membranes in a two-compartment diffusion cell AH20 ( ), AS 15 (A), AS20 ( ), H ( ). Numbers indicate the content of styrene or HEMA in feed compositions in moles. H represents a cross-linked poly(2-hydroxyethyl methacrylate) (HEMA). (From Ref. 34.)... 

An NIR optical fiber for the detection of metal ions has been developed In a controlled environment, the optical probe with immobilized NIR dye was immersed in vials containing different metal ions varying in concentrations from 10 9 to 1CT2 M. The probe response was obtained by the diffusion of the metal ions through the poly(2-hydroxyethyl methacrylate) (PHEMA) polymer matrix where the dye was covalently attached. On complexation of the metal with the dye, the intensity of the fluorescence signal increased. 

Physical incorporation of different porphines (9) and also phthalocyanines (2) into polymer matrices were done by pearl polymerisations of glyddyl or 2-hydroxyethyl methacrylate and ethylene dimethacrylate -The amount of inorrporated dtielate is 0,05 to 0.4 wt %(50-70% of the inserted porphyrine). The surface hole is small enough to prevent diffusion of N4-chelates from the interior of the matrix. Also polymers, sudi as polystyrene or polyvinylalcohole, were directly used to incorporate porphyrines or phthalocyanines. ... 

Deodhar et al. [16]), and, therefore, desalting cannot be expected for pores larger than this range. Permeation measured by Kim et al. [20] for hydrophilic solutes in aqueous media through poly(hydroxyethyl methacrylate) (p-HEMA) is consistent with transport by bulk-like water. Permeation is reduced for crosslinked p-HEMA or HEMA copolymers as a result of non-bulk-like water. Southern and Thomas [22] showed that hydrophilic impurities in rubber provide loci for water molecules and account for diffusion of aqueous solutions through this hydrophobic substrate. 

Hydrophilization of AO adsorbents is effective in improving the uranium adsorption rate the diffusion of uranyl tricarbonate ion, which is the predominant species of dissolved uranium in seawater, governs the overall adsorption rate of uranium. Cografting of methacrylic acid (CH2=CCH3C00H, MAA) and 2-hydroxyethyl methacrylate (CH2=CCH3COOCH2CH20H, hem A) with AN onto PE and PP fibers was suggested as a method of enhancing the adsorption of uranium on AO adsorbents [105,106]. 

Copolymers of 2-hydroxyethyl methacrylate (HEMA) and l-vinyl-2-pyr-rolidone (VP) in the form of cylindrical hydrogels (8 mm x 20 mm) have been prepared radiochemically and the sorption of water into these cylinders has been studied by the mass-uptake methods and by magnetic-resonance imaging at 310 K. The equilibrium water contents for the cylinders were found to vary systematically with the copolymer composition. NMR-imaging studies showed that, while the profiles of the water diffusion fronts for cylinders with high HEMA contents were Fickian, those for the 1 1 copolymer was not and indicated that the mechanism was Case III. The polymers which were rich in VP were characterized by a water-sorption process which follows Case-III behavior. 

With the encapsulation process, the enzyme is dissolved in a solution of monomer, cross-linking agent, and initiator, and the solution then polymerized. Acrylamide or 2-hydroxyethyl methacrylate are the monomers most often used. The simplest procedure embeds the enzyme in the polymer matrix. But enzyme accessibility is reduced because of more difficult diffusion... 

Under the assumption of bimolecular termination, the reaction diffusion parameter R (equation (4.2)) was determined for the bulk photopolymerization of multifunctional (meth)acrylates [I, 3, 6, 17, 481. It was found that for methacrylates at the plateau level, R was in the order of 2 1 moP [6] and for acrylates R was 3-5 1 moP [I7J. In general, reduction of network cross-linking density by co-polymerization with a difunctional reactive diluent (2-hydroxyethyl methacrylate (HEMA), octyl methacrylate) [3] increased the values of R due to increased mobility of the polymerization system until a plateau is reached. The addition of an inert diluent (polyethylene glycol 400 (PEG 400) [3, 6] or hydrogenated monomers [25. 53]) to a flexible monomer of low viscosity did not change R,... 

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