Surface grafted polyethylene

Wilson, at Bishop College, and Eberhart and Elkowitz at University of Texas (27) have irradiated a silicone substrate in the presence of chloromethylstyrene monomer to produce a reactive graft polymer that can be quarternized with pyridine and reacted with sodium heparin to produce a thromboresistant heparinized product that has a higher blood compatibility than the untreated silicone. The same group has used essentially the same methods to create a heparin grafted polyethylene surface. 

Mori M, Ishihara M, Okumura J, Yamaguchi K, Nakamae K (2003) Immobilization of viologen moieties on poly(acrylic acid)-grafted polyethylene surface. Sen i Gakkaishi 59 260-265... 

Polyethylene film kinetics of surface grafting, 174/ surface grafting, 178/... 

The interaction of the polymer with the filler is promoted by the presence of reactive functionality in the polymer, capable of chemical reaction or hydrogen bonding with the functionality, generally hydroxyl, on the surface of the filler. Thus, carboxyl-containing polymers, e.g. ethylene-acrylic acid copolymers and maleic anhydride- and acrylic acid-grafted polyethylene and polypropylene interact readily with fillers. 

A similar approach was used in grafting Cjq onto a pregenerated lithiated polyethylene surface [121]. A polyethylene film with terminal diphenylmethyl groups was deprotonated with BuLi to yield an anionic polyethylene surface that was treated with Cg0 and quenched with methanol. The incorporation at the polyethylene surface was determined by XPS, UV/Vis and fluorescence spectroscopy. This reaction also works for polyisopropene, polybutadiene [69], poly(vinylbenzyl chloride) or poly(N-vinylcarbazole) PVK [54] with BuLi or NaH as a base. Charge-transfer interactions in the soluble fullerene-PVK derivative between the positively charged carbazole and Cjq lead to an enhanced photoconductivity compared with PVK [54]. 

Polyethylene glycols are well known as protein-compatible molecules when coated or grafted onto surfaces. Both protein and platelet adsorptions to polyethylene glycol (PEG)-modified surfaces were shown to be reduced by PEG chains when attached to surfaces at one end of a molecule. Adsorption and platelet attachment were shown to be inversely proportional to the length of the PEG chain 100 monomer units provided minimal adsorption and adherence.- ... 

Keywords Polyethylene Surface modification Characterisation Grafting Radiation... 

D. Leckband, S. Sheth, and A. Halperin, Grafted polyethylene oxide) brushes as non-fouling surface coatings, J. Biomater. Sci. Polymer Ed. 10 1125-1147 (1999). 

An elegant example of the analysis of colloid surfaces containing covalently attached hydrophilic species has been provided by Brindley et al who studied the surface chemistry of polystyrene colloids with surface grafted polyethylene glycol groups [39]. These colloids were prepared by surfactant-free copolymerization of styrene with PEG using potassium persulphate as an initiator. The XPS analysis of these microparticles is shown in Fig. 11. 

Figure 2. Outline of the surface reactions on poly(maleic anhydride) grafted polyethylene.

However, in spite of these similarities, the adsorbed amounts and the structure of the adsorbed mucin and collagen layers on the surfaces studied are entirely different. The behavior of these proteins is analyzed here on the hydrophobic polyethylene surface (water contact angle 0 20 95°), on the surface modified polyethy-lenes oxidized polyethylene (0h q 74°) and poly(maleic acid) grafted polyethylene ( Ho0 74°) a d on the hydrophilic mica surface ( H2 0 0°) Acidic pH = 2.75 (for collagen) and slightly alkaline pH = 7.2 (for mucin) were chosen in order to minimize the association of these proteins in solution and to make possible the analysis of their adsorbabilities in comparable conditions. 

The surface density/solution concentration isotherms, not shown in this paper, reflect also the differences in the behavior of mucin and collagen upon their adsorption at solid interfaces. While the collagen isotherms on polyethylene and surface-grafted polyethylene show a plateau of adsorption at solution concentrations higher than 0.05 mg/ml, no plateau values for mucin adsorption are observed on polyethylene and surface oxidized polyethylene. 

Figure 9. Desorption-adsorption relationships (a) polyethylene-collagen (a) poly(maleic acid) grafted polyethylene-collagen (o) polyethylene-mucin ) surface oxidized polyethylene-mucin. Adsorption time 20 hrs temp. 20°C. Adsorption conditions as indicated in Figure 7.

Low-density polyethylene (LDPE) is commonly used biomaterial which possesses fairly good grafting reactivity compared to other common polymeric materials. A number of plasma modification and plasma polymerization systems have been employed in order to incorporated oxygen-containing functional groups onto polyethylene surfaces for biomaterial applications. i Tiie aim of this work was to introduce acidic sulfur-containing functional groups onto LDPE surfaces by plasma treatment and to assess the potential blood compatibility of the modified materials. 

Branch DW, Wheeler BC, Brewer GJ, Leckband DE (2(X)1) Long-term stability of grafted polyethylene glycol surfaces for use with microstamped substrates in neuronal cell culture. Biomaterials 22 1035... 

Fig. 11.10 The SEM images of a the viscose fibers and the fracture surfaces of b HOPE, c HDPE-PEgMA (maleic anhydride grafted-polyethylene), d HDPE-PEgMA-fiber (5 wt%), e HDPE-PEgMA-fiber (10 wt%), f HDPE-PEgMA-fiber (20 wt%), g HDPE-PEgMA-fiber (40 wt%), and h HDPE-fiber (40 wt%) [56]...

K. Kildal, K. Olafsen, A. Stoni, Peroxide-initiated grafting of acrylamide onto polyethylene surfaces. Journal of Applied Polymer Science 44 (1992) 1893. 

Fig. 24a-g. Phase-contrast micrographs of surfaces which are in contact with platelet-rich plasma, a, glass b, siliconized glass c, polyethylene d, poly(vinyl alcohol) e, acrylamide-grafted polyethylene f, acrylic acid-grafted polyethylene g, sodium acrylate-grafted polyethylene. Scale is given in a... 

Sun, Y., Hoffman. A. S., and Gombotz, W. R.. Non-fouling biomaterial surfaces II. Protein adsorption on radiation grafted polyethylene glycol methacrylate copolymers, Polym. Prep., 25(1) 292 (1987). 

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