Polyethylene grafted chains

PEG has been converted into a solid support by grafting functionalized polyethylene glycol chains onto polystyrene to form constructs such as TentaGel ... 

The Acid Effect. The possible mechanistic role of hydrogen atoms in the current radiation grafting work becomes even more significant when acid is used as an additive to enhance the copolymerisation. At the concentrations utilised, acid should not affect essentially the physical properties of the system such as precipitation of the polystyrene grafted chains or the swelling of the polyethylene. Instead the acid effect may be attributed to the radiation chemical properties of the system. Thus Baxendale and Mellows (15) showed that the addition of acid to methanol increased G(H2) considerably. The precursors of this additional hydrogen were considered to be H atoms from thermalised electron capture reactions, typified in Equation 5. 

Radiation-Induced Cross-Linking in the Presence of CTFE/Butadiene Mixture. On the basis of the results mentioned in the previous section, it is concluded that in the irradiation of polyethylenes in the presence of CTFE the polyethylenes are mainly cross-linked through the addition reaction of the unsaturated groups contained in the main and the side chains of the polymers to the propagating graft chain radical of CTFE. Therefore, the radiation-induced cross-linking of polyethylene is expected to be accelerated by the presence of the mixture of CTFE and a diene monomer effectively than the presence of pure CTFE. 

A large number of researches have been carried out in order to obtain biocompatible hydrophilic surfaces by introducing water-soluble polymer grafts, including polyethylene glycol), polyacrylamide and poly(vinyl alcohol). It was, however, occasionally observed that there is an optimum in the number of grafted chains for the surface to exhibit the best biocompatibility. The discussions in Sect. 3 will present an approach to a possible elucidation of this problem. A very unique property of poly(JV-isopropylacrylamide) as thermores-ponsive hydrogel will also be discussed in this chapter. 

Sometimes branched units are synthesized and further condensed to graft copolymer e.g. dimethylterephthalate carrying in the aromatic nucleus polyethylene oxide chains is transesterified with ethylene glycol and polycondensed. 

A DEA group was appended onto a polyethylene porous hollow-fiber membrane with a density of 2.2 mmol per gram of the resultant DEA-EA fiber. The inner and outer diameters of the hollow fiber were 2.4 and 4.4 mm, respectively. The liquid permeability, i.e., the permeation rate per unit of inside surface area, of the DEAEA fiber for the buffer was maintained at 50% of that of the original hollow fiber. Volume swelling of the porous hollow fiber accompanied by graft polymerization prevented the graft chains from filling the pores. 

FIGURE 16.8 Introduction of initiator onto a polyethylene film and polymerization by ATRP of MMA. (Komatsu, M., Kawakami, T., Kanno, J.I., and Sasaki, T. Atom transfer radical polymerization of graft chains onto polyethylene film initiated at tribromomethyl unit introduced by electron beam irradiation. /. Appl. Polym. Sci. 2011. 119. 2533-2538. Copyright Wiley-VCH Verlag GmbH Co. KGaA. With permission.)... 

Komatsu, M., T. Kawakami, J.I. Kanno and T. Sasaki. 2011. Atom transfer radical polymerization of graft chains onto polyethylene film initiated at tribromomethyl unit introduced by electron beam irradiation. JAppl Polym Sci 119 2533-2538. 

---