Hydroxyethyl graft

Emulsion polymerizations of vinyl acetate in the presence of ethylene oxide- or propylene oxide-based surfactants and protective coUoids also are characterized by the formation of graft copolymers of vinyl acetate on these materials. This was also observed in mixed systems of hydroxyethyl cellulose and nonylphenol ethoxylates. The oxyethylene chain groups supply the specific site of transfer (111). The concentration of insoluble (grafted) polymer decreases with increase in surfactant ratio, and (max) is observed at an ethoxylation degree of 8 (112). 

The effect of Fe(II) on grafting of 2-hydroxyethyl methacrylate onto polyester fibers in the presence of benzoyl peroxide was investigated [59]. It was found that increasing the iron ion concentration decreases the graft yield. This suggest that excess Fe(ll) ions participate in the generation of free radical species and the iron ions seem to contribute to the termination and, consequently, decrease the graft yield. 

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. 

A polymeric composition for reducing fluid loss in drilling muds and well cement compositions is obtained by the free radical-initiated polymerization of a water-soluble vinyl monomer in an aqueous suspension of lignin, modified lignins, lignite, brown coal, and modified brown coal [705,1847]. The vinyl monomers can be methacrylic acid, methacrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, vinylacetate, methyl vinyl ether, ethyl vinyl ether, N-methylmethacrylamide, N,N-dimethylmethacrylamide, vinyl sulfonate, and additional AMPS. In this process a grafting process to the coals by chain transfer may occur. 

The enzymatic polymerization of lactones could be initiated at the hydroxy group of the polymer, which expanded to enzymatic synthesis of graft copolymers. The polymerization of c-CL using thermophilic lipase as catalyst in the presence of hydroxyethyl cellulose (HEC) film produced HEC-gra/f-poly( -CL) with degree of substitution from 0.10 to 0.32 [102]. 

Thiol end-functionalized poly(2-hydroxyethyl methacrylate-g-ethylene glycol) graft copolymers were synthesized by ATRP copolymerization of... 

A new class of amphiphilic, surface-active graft copolymers, hydrophobically modified hydroxyethyl celluloses (HM-HEC s), are comprised of a cellulose backbone with short polyethylene oxide (PEO) and grafted alkyl side chains. They are excellent steric stabilizers of 0/W emulsions. 

Fig.44 (left) Dry thickness (in nm) of a poly(2-hydroxyethyl methacrylate) (PHEMA) brush in an orthogonal gradient as a function of the PHEMA grafting density and molecular weight The scale represents the thickness of dry polymer (in nm). (right) Adsorbed amount of lysozyme as a fimction of the position on the orthogonal PHEMA gradient. The scale represents the fluorescence intensity (in a.u.). (Reproduced with permission from [164])... 

Mei Y, Wu T, Xu C, Langenbach KJ, Elliott JT, Vogt BD, Beers KL, Amis EJ, Washburn NR (2005) Tuning cell adhesion on gradient poly(2-hydroxyethyl methacrylate)-grafted surfaces. Langmuir 21 12309-12314... 

A series of polymine-graft copolymers of styrene [92-95] and hydroxyethyl methacrylate [96-98] were found to form a microdomain structure and exhibit unique biomedical behavior at the interface with living cells, such as blood platelets and lymphocytes. The most intensive studies were made with poly(hydroxyethyl methacryIate)-0ra/t-polyamine copolymers (HA) ... 

Valerio, R. M. Bray, A. M. Campbell, R. A. DiPasquale, A. Margellis, C. Rodda, S. J. Geysen, H. M. Maeji, N. J. Multipin Peptide Synthesis at the Micromole Scale using 2-Hydroxyethyl Methacrylate Grafted Polyethylene Supports, hit. J. Pept. Protein Res. 1993, 42, 1. 

Polyethylene has been grafted with acrylic acid, 2-hydroxyethyl methacrylate//V,/V-dimethylacrylamide, or methacrylic acid//V,/V-dimethylacrylamide to yield supports (e.g. Figure 2.10) suitable for the synthesis of peptides [2,222-224] and other compounds [216,225,226]. A similar support, also suitable for the synthesis of peptides, is polypropylene grafted with hydroxypropyl acrylate [227]. These supports can be used as membranes or as crown-shaped pinheads (Multipin 2-4 mm diameter) with loadings of 1.2-2.2 pmol per crown. 

Figure 2.10. Hydroxyethyl methacrylate grafted onto polyethylene [2,224],...

Hydroxyl groups may also be introduced in the polymer by graft-copolymerization of hydroxyethyl methacrylate or glycidyl methacrylate, the latter being subsequently hydrolyzed 91). Heparin was immobilized on such hydroxyl-containing polymers by means of glutaric dialdehyde. The maximal amount of polymer-bound heparin was 80 ng/cm2. 

A rather similar dependence was observed by Hoffman et al. 98) for heparin covalently immobilized on silicone rubber, which had been pre-modified by graft-copolymerization of hydroxyethyl methacrylate and N-vinylpyrrolidone (Table 11). 

Inoue et al.1115,1161 synthesized polyvinyl/polypeptide graft copolymers by attaching branches of p-phenylazobenzyl/P-benzyl-L-aspartate (X) to poly(hydroxyethyl methacrylate) and poly(butyl methacrylate), and then prepared the corresponding membranes by casting dichloroethane solutions of the polymers. The membranes were stable in trimethylphosphate. 

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]. 

Substrates of hydroxyethyl cellulose (HEC) samples of different molar substitution (MS) of oxirane give similar results in grafting with AN as EC (Table IV). At MS-values of 0.40 and 0.60, the water solubility influences the results, especially the grafting efficiency. HEC-samples of low MS (0.25) give the best results in grafting. 

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