HEMA - hydroxyethyl methacrylate

Dielectric relaxation measurements of polyethylene grafted with acrylic acid(AA), 2-hydroxyethyl methacrylate (HEMA) and their binary mixture were carried out in a trial to explore the molecular dynamics of the grafted samples [125]. Such measurements provide information about their molecular packing and interaction. It was possible to predict that the binary mixture used yields a random copolymer PE—g—P(AA/HEMA), which is greatly enriched with HEMA. This method of characterization is very interesting and is going to be developed in different polymer/monomer systems. 

Hoffman and his coworkers have done a lot of work on the apphcation of radiation-induced graft polymerization for medical apphcation. The hydrophilic polymers that have been used for radiation-induced grafting are Al-vinyl pyrohdone (NVP), 2-hydroxyethyl methacrylate (HEMA), acrylamide (AAm), acrylic acid (AAc), glycidyl methacrylate (GMA), ethyleneglycol dimethacrylate (EGDMA), and ethyl methacrylate (EMA) onto sihcone rubber were widely smdied. 

Materials. 2-Hydroxyethyl methacrylate (HEMA, Aldrich Chemical Co.) and chlorotrimethylsilane (Cl-TMS) (Lancaster Synthesis Inc.) were used as received. The source and purification of the other chemicals has been described (7). 

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.)... 

Figure 14.6.4 The molecular structure of the monomer 2-hydroxyethyl methacrylate (HEMA).

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. 

A variety of photo-initiators and water-soluble diluents were used to study the photopolymerization of 2-hydroxyethyl methacrylate (HEMA). The rate of polymerization can be correlated to the structures as well as the concentration of initiators and diluents. It was found that, in terms of rate of polymerization,... 

In this work, the kinetics of these reactions are closely examined by monitoring photopolymerizations initiated by a two-component system consisting of a conventional photoinitiator, such as 2,2-dimethoxy-2-phenyl acetophenone (DMPA) and TED. By examining the polymerization kinetics in detail, further understanding of the complex initiation and termination reactions can be achieved. The monomers discussed in this manuscript are 2-hydroxyethyl methacrylate (HEMA), which forms a linear polymer upon polymerization, and diethylene glycol dimethacrylate (DEGDMA), which forms a crosslinked network upon polymerization. 

The monomers studied, 2-hydroxyethyl methacrylate (HEMA) and diethylene glycol dimethacrylate (DEGDMA), were obtained from Aldrich (Milwaukee, WI) and Polysciences, Inc. (Warrington, PA), respectively, and were used after dehibition to remove the hydroquinone inhibitor. 2,2-Dimethoxy-2-phenyl acetophenone (DMPA), the conventional initiator used in this study, was obtained from Ciba-Geigy (Hawthorne, NY) and the tetraethylthiuram disufide (TED) was obtained from Aldrich. 

POLYMERIZATION OF 2-HYDROXYETHYL METHACRYLATE (HEMA) AND METHYL METHACRYLATE (MMA)... 

Cavity varnishes are used to seal the exposed dentinal tubules and protect the pulp from the irritation of chemicals in the filling materials. They are generally largely NR or a synthetic polymeric resin such as 2-hydroxyethyl methacrylate (HEMA). 

If ATRP is conducted in methanol, under the same conditions, the rate of polymerisation is slower (95% conversion required 2-5 h at 20 °C). However, for several hydrophilic monomers such as 2-hydroxyethyl methacrylate [HEMA] and glycerol monomethacrylate [GMA], methanolic ATRP is the preferred method for optimal living character since narrower polydispersities (typically 1.10 to 1.20) and better blocking efficiencies are generally obtained. 

We have recently evaluated the ATRP of a wide range of hydrophilic monomers such as 2-sulfatoethyl methacrylate (SEM), sodium 4-vinylbenzoate (NaVBA), sodium methacrylate (NaMAA), 2-(dimethylamino)ethyl methacrylate (DMA), 2-(iV-morpholino)ethyl methacrylate (MEMA), 2-(diethylamino)ethyl methacrylate (DEA), oligo(ethylene glycol) methacrylate (OEGMA), 2-hydroxyethyl methacrylate (HEMA), glycerol monomethacrylate (GMA), 2-methacryl-oyloxyethyl phosphorylcholine (MPC), and a carboxybetaine-based methacrylate [CBMA]. Their chemical structures and literature references (which contain appropriate experimental details) are summarised in Table 1. 

Polyurethane hydrogels derived from UV curable urethane prepolymer and hydrophilic monomers were prepared and their properties were evaluated. The urethane prepolymer used in this study contained well-defined hard segments centered with a polyether-based soft segment and end-capped with methacrylate groups. The hydrophilic monomers studied were 2-hydroxyethyl methacrylate (HEMA), N-vinyl pyrrolidone, and glycerol methacrylate. Methacryloxypropyl tris(trimethysiloxy) silane (TRIS) was also used in some cases to modify properties. All compositions were UV... 

Complementary results for polyacid gels have also been obtained. In studies using copolymers of 2-hydroxyethyl methacrylate (HEMA) and methacrylic acid (MA), at a 78/22 monomolar ratio, Chou et al. [45] measured swelling rates in both unbuffered and buffered solutions. In these gels, ionization occurs by... 

A means to avoid such tedious optimization can be envisaged by employing stoichiometric monomers to develop strong interactions with the template as mentioned above. The other way is to incorporate hydrophilic comonomers (2-hydroxyethyl methacrylate (HEMA), acrylamide) or cross-linkers (pentaerythri-toltriacrylate, methylene bisacrylamide) in the polymer. This results in an increase of the hydrophilicity of the polymer. Indeed, the use of HEMA for a MIP directed towards the anesthetic bupivacaine resulted in high imprinting factors due to reduced non-specific hydrophobic adsorption in aqueous buffer. This was not the case when HEMA was omitted from the polymerization mixture [27]. These conditions were exploited for the direct and selective extraction of bupivacaine from blood plasma samples. 

Surface polymerization of 2-hydroxyethyl methacrylate (HEMA), which possessed a functional group, at the initiation sites on the molded sheet of the PP macroinitiator was performed by Matsuo et al. using the ATRP-mediated CuBr/PMDETA catalyst system [148]. The molded PP sheet (d = 1.0 mm) was prepared by a molding press from PP-Br, which was synthesized by bromina-tion of propylene/10-undecen-l-ol copolymer (PP-OH Mn = 15 500, [-OH] = 3.8 units/chain). The ATRP of HEMA was carried out on the molded PP-Br... 

Transparent hydrogels useful for adhesion inhibitors, tissue adhesives, wound dressings, hemostatics and embolisation materials are obtained from dextran methacrylates via polymerisation with N-isopropylacrylamide in DMSO in the presence of azobisisobutyronitrile [176]. A broad variety of new hydrogels with different sensitivities and tunable degradation behaviour is accessible by grafting L-lactide onto 2-hydroxyethyl methacrylate (HEMA) and binding this polymerisable group on dextran via activation with N,N -carbonyldiimidazole (CDI, Sect. 4.2.2) [177]. 

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