Poly-2-hydroxyethyl-methacrylate p-HEMA

One particular hydrophobic polymer, EVAc, has been investigated extensively as a matrix system for protein delivery. This polymer is biocompatible, a major consideration because of the interest in developing systems for human health. Other classes of hydrophobic polymers, like silicone elastomers and polyurethanes, may also be useful for controlled protein delivery, although there are fewer examples available in the literature. Nondegradable, hydrophilic polymers, such as poly(2-hydroxyethyl methacrylate) [p(HEMA)], are also biocompatible but usually release proteins over a relatively short period. However, a few examples oflong-term release of peptides and proteins from hydrophilic polymers are available. Longterm release of peptides from devices that employ cross-linked p(HEMA) as rate-limiting barriers has been reported (Davidson et al, 1988). The use of hydrophilic polymers for protein release is discussed in more detail elsewhere in this volume. 

Among the methacrylate hydrogels, the most common gelating polymer is poly-2-hydroxyethyl-methacrylate (p-HEMA) [19]. The monomer and the aqueous... 

Most research into the study of dispersion polymerization involves common vinyl monomers such as styrene, (meth)acrylates, and their copolymers with stabilizers like polyvinylpyrrolidone (PVP) [33-40], poly(acrylic acid) (PAA) [18,41],poly(methacrylicacid) [42],or hydroxypropylcellulose (HPC) [43,44] in polar media (usually alcohols). However, dispersion polymerization is also used widely to prepare functional microspheres in different media [45, 46]. Some recent examples of these preparations include the (co-)polymerization of 2-hydroxyethyl methacrylate (HEMA) [47,48],4-vinylpyridine (4VP) [49], glycidyl methacrylate (GMA) [50-53], acrylamide (AAm) [54, 55], chloro-methylstyrene (CMS) [56, 57], vinylpyrrolidone (VPy) [58], Boc-p-amino-styrene (Boc-AMST) [59],andAT-vinylcarbazole (NVC) [60] (Table 1). Dispersion polymerization is usually carried out in organic liquids such as alcohols and cyclohexane, or mixed solvent-nonsolvents such as 2-butanol-toluene, alcohol-toluene, DMF-toluene, DMF-methanol, and ethanol-DMSO. In addition to conventional PVP, PAA, and PHC as dispersant, poly(vinyl methyl ether) (PVME) [54], partially hydrolyzed poly(vinyl alcohol) (hydrolysis=35%) [61], and poly(2-(dimethylamino)ethyl methacrylate-fo-butyl methacrylate)... 

Monomers 4VP, 4-vinylpyridine NIPAAm, jV-isopropylacrylamidc AA, acrylic acid PEGMA, poly (ethylene glycol) methacrylate SPE, MAI-dimethyl-AW2-methacryloyloxycthyl-/V-0-sulfopropyl)amm<>-nium betaine AMPS, 2-acrylamido-2-methyl-l-propanesulfonic acid qDMAEMA, quaternary 2-dimethylaminoethyl methacrylate St, styrene HEMA, 2-hydroxyethyl methacrylate HEA, 2-hydro-xyethyl acrylate DMAEMA, 2-dimethylaminoethyl methacrylate MAA, methacrylicacid NaSS sodium p-styrene sulfonate AC, [(2-acryloyloxy)ethyl]trimethyl ammonium chloride GMA, glycidyl methacrylate NVP, jV-vinylpyrrolidone MAn, maleic anhydride BVE n-butyl vinyl ether AAm, acrylamide DEAAm, MA-diethylacrylamidc DMAAm, MA -dimethylacrylamidc MMA, methyl methacrylate. 

C2H, C2F, CjH. Ar Prfy(2-hydroxyethyl methacrylate) (Poly(HEMA)) P<release rate from l diogd... 

The molecularly imprinted copolymer of 2-hydroxyethyl methacrylate (HEMA) and p-CyD-coupled HEMA was synthesized in chloroform to study its interaction with a pair of steroids cholesterol and testosterone [42]. The molecularly imprinted copolymer was found to absorb the print molecule several times better than an imprinted poly HEMA. Asanuma et al. [44] concluded that cholesterol binding by the HEMA polymer was not due to CyD inclusion because no inclusion of CyD to cholesterol can form in chloroform. Another strategy developed for imprinting using CyD elements is the vinyl CyD (Table 1 and 10.3(A)), which has been successfully applied for imprinting antibodies, oligo-peptides [45], and vancomycin [46[. 

A change in the hydrophilic nature of the polymer surface on irradiation of poly(p-phenylazoacrylanilide) or its copolymer with 2-hydroxyethyl methacrylate (HEMA) could affect the adsorption-desorption behavior of proteins or organic substances onto the polymer. Adsorption of lysozyme onto the copolymer of p-phenylazoacylanilide and HEMA decreased from 4.6 to 1.8 eg g of adsorbent on UV irradiation, which induces the isomerization from trans- to cis-form [16]. Table 2 summarizes the results of other proteins adsorption studies. Considering the similarity in molecular weight of the three proteins, the difference in adsorption behavior is probably due to the difference in the surface characteristics of these proteins. The decrease in adsorption ability on UV irradiation is attributable to the reduction of hydrophobic interaction between the protein and the polymer by the appearance of hydrophilic cis-azobenzene on the surface. 

We examined the homopolymerizations and copolymerizations of styrene (St), methyl methacrylate (MMA), acrylonitrile (AN), a functional styrene, i.e., p-aminostyrene (ASt), and functional methacrylates, i.e., 2-ethyhexyl (EHMA), benzyl (BzMA), phenyl (POMA), glycidyl (GMA), 2-hydroxyethyl (HEMA), poly(ethylene glycol) methyl ether (PEGMA), and A,A-dimethylaminoethyl (DMAEMA) methacrylates as well as methacrylic acid (MAA) (Figure 7.2), for example, by using several catalysts. The results will be summarized below. 

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