Hydroxyethyl methacrylate application

Montheard,J.P.,Chatzopoulos,M.and Chappard, D. (1992) 2-hydroxyethyl methacrylate (HEMA) - chemical properties and applications in biomedical fields. Journal of Macromolecular Science — Macromolecular Review, 32, 1—34. 

Poly(2-hydroxyethyl methacrylate) (PHEMA) has been the most widely used polymer in drug delivery applications. It is an extremely hydrophilic... 

Anderson, J. M., Komis, T., Nelson, T., Horst, M., and Love, D. S., The Slow Release of Hydrocortisone Sodium Succinate from Poly(2-Hydroxyethyl Methacrylate) Membranes, in Hydrogels for Medical and Related Applications (J. D. Andrade, Ed.), American Chemical Society Washington, pp. 167-178. 1976. 

Applications of hydrogels include highly absorbent diapers based on poly(sodium acrylate), contact lenses based on poly(2-hydroxyethyl methacrylate) (polyHEMA), and switches based on variations of swelling of the hydrogels. A number of drug delivery systems have also been based on hydrogels. 

This was conhrmed in 1967 by Kubin et al., who were the first to accomplish polymerization directly in a glass colnmn [13], The resulting swollen poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) gel, which was prepared in the presence of 1% cross-linker, was strongly compressed after pressnre application and consequently exhibited exceedingly low permeability (4.5mL/h for a 25 X 220 mm colnmn) and poor efficiency. 

The polymerization described so far is homo-polymerization based on single monomers. Some polymers used in pharmaceutical applications are copolymers. They have properties that each homo-polymer does not exhibit. For example, the copolymer of hydroxyethyl methacrylate and methyl methacrylate is synthesized in order to obtain a polymer exhibiting a hydrophilic/hydrophobic balance. A variety of copolymers (alternating, block, random) can be formed from two different monomers. Special processes produce alternating and block copolymers, while random copolymers are produced by free-radical copolymerization of two monomers. The polymerization steps, such as initiation, propagation, and termination, are the same as in free-radical homo-polymerization. Copolymerization kinetics are depicted as follows ... 

For the moderately hydrophilic hydroxyethyl methacrylate, cyclohexane and hexadecane were chosen as the continuous phase. As initiators, PEGA200 which is soluble in the monomer phase, but not in cyclohexane, turned out to be applicable. AIBN which is mainly soluble in the cyclohexane phase could also be successfully used. KPS cannot be employed as initiator due to solubility problems. Small amounts of water act as lipophobe, and it could be shown by turbidity measurements that the addition of water increases the emulsion stability. 

In an earlier investigation by the author [3] Step 2 analogues containing 2-hydroxyethyl methacrylate were prepared and used as rubber components in engineered plastics for automotive applications. 

Copolymerization of di- and trimethacrylates with functionalized monomers, like glycidyl methacrylate, leads to low-viscosity oligomers capable of nonradical cross-linking. This process promises substantial value for industrial applications. Star polymers useful in coatings were prepared by copolymerizing methacrylate macromonomers with diacrylates.519 For instance, a star polymer was synthesized by copolymerization of a 2-ethylhexyl methacrylate/isobutyl methacrylate/hydroxyethyl methacrylate macromonomer with butanediol diacrylate. 

In a third example of this methodology Mei et al. [65] produced a polymer containing the fibronectin-based peptide sequence GRGDS, a well-known cell adhesion sequence. This time, however, the polymerization of hydroxyethyl methacrylate was carried out on the sohd support in methyl ethyl ke-tone/propanol (7 3), resulting in a bio-hybrid with a polydispersity of 1.5. This peptide-polymer hybrid material was used as a support for the growth of mouse NIH-3T3 fibroblasts. It was shown that the cells adhered better to the polymer containing the peptide than to the unfunctionalized control polymer. This highhghts one of the many potential applications for protein-polymer hybrid materials. 

Polyt2-hydroxyethyl methacrylate) Cp-HEMA) is a hydrophilic methacrylate polymer which was first prepared by Wichterle and Lim (.1). This polymer, and many other synthetic hydrogels, has been extensively examined for potential biomedical applications (2 ). Although many studies have focused on the physicochemical nature of these hydrogels, many questions remain unanswered. 

The reaction with aryl radicals of this kind has found an interesting application in the direct polymerization of vinylic monomers like styrene, methyl methycrylate (MMA), or hydroxyethyl methacrylate (HEMA) on the diamond. Furthermore, the covalent attachment of an initiator molecule allows for an atom transfer radical polymerization (ATRP) to take place immediately on the diamond surface and results in a covalently bound composite material (Figure 6.41). 

Synthetic hydrogels have been frequently used in biomedical applications, because of the similarity of their physical properties to living tissues [3]. The most widely used synthetic hydrogels are polymers of acrylic acid, acrylamide, and 2-hydroxyethyl methacrylate (HEMA) ... 

For biomedical applications, the most frequently encountered synthetic hydrogel is poly(2-hydroxyethyl methacrylate) (pHEMA). The characterization and applications of pFIEMA have been reviewed [4]. Both HEMA and pHEMA are easy and inexpensive to produce. Because of the primary alcohol, the monomer or polymer can be functionalized. In addition, HEMA can be copolymerized... 

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