Preparation of ion‐exchange membranes by hydrolysis of radiation‐grafted polyethylene‐g‐polyacrylamide membranes

Abstract

Polyethylene-g-polyacrylamide membranes were prepared by graft polymerization of acrylamide onto polyethylene films using a preirradiation method. The ionexchange membranes were obtained by the hydrolysis of grafted films so as to transform amide groups into carboxyl groups. The fraction of amide groups transformed into carboxyl groups was limited to ϳ0.5. The characterization and thermal behavior of membranes with different degrees of grafting were evaluated by FTIR, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) measurements. The heat of fusion and the crystallinity of polyethylene decreased considerably in the hydrolyzed membranes depending on the degree of grafting. It was found that the grafting of acrylamide led to the reduction in crystallinity due to disruption of the crystallites (crystal defects) and dilution of the inherent crystallinity (dilution effect). The contribution of the hydrolysis step to the crystallinity decrease was negligible. The thermal stability of the membranes as obtained from TGA showed considerable enhancement after hydrolysis.

Calcium ion‐mediated grafting of a phosphate‐containing monomer

“…A plateau (observed in this study for the 30% and 40 % MAEP concentrations) has similarly been observed previously. 37,38 This observation has been attributed to an increase in solution viscosity at high monomer concentration. The higher degree of grafting which has been frequently observed with a higher dose 32,33,39 can be attributed to a higher concentration of substrate radicals which in turn leads to a higher number of grafted chains.…”

Temperature‐Sensitive Hydrogel Pattern by Electron‐Beam Lithography

“…A suitable tool for the synthesis of patterned structures is electron-beam lithography. [24][25][26] In a high vacuum, the accelerated electrons are focused on a substrate by lens systems. Nonsensitive hydrogel patterns based on poly(ethylene oxide) (PEO) on Si substrates were synthesized by using the focused electron beam (typically with diameter d % 10 nm) of a field-emission electron microscope.…”

CHAPTER 11. Grafting of Functional Monomers on Biomaterials

“…16 This phenomenon is attributed to an increase in solution viscosity at high monomer concentration. 17 …”

“…In contrast to gamma rays, electron beam needs much shorter time of exposure of the substrate to the irradiation source and as such has less of an effect on the bulk properties. 17 When UV is used as the radiation source, the grafting of monomers is a two-step process. In the first step a photo-initiator, such as benzophenone (BP; a Norrish type II photo-initiator) is irradiated with the substrate and in the second step, this pre-treated and washed substrate is irradiated in the presence of a monomer.…”