Superabsorbent hydrogel of acrylic acid/potassium acrylate copolymers by ultraviolet photopolymerization: Synthesis and properties

Abstract

Synthesis of superabsorbent hydrogel (SAHG) of acrylic acid-potassium acrylate copolymer by direct Ultraviolet (UV) photopolymerization is a new method. The effects of degree of neutralization of acrylic acid (AA), photoinitiators, crosslinking agents, and exposure time of UV light on water absorbent properties were investigated. The results showed that the water absorbency (Q) and the salt solution (NaCl, 0.9%) absorbency (Qs) of SAHG, based on Irgacure 651, are high, reaching about 1400 and 130 mL/g, respectively. UV absorption spectrum proved that peak of UV absorption of Irgacure 651 matched the UV light source we used. Among the crosslinking agents, N,NЈ-methylene bisacrylamide is more efficient than others, because of its very small content and high Q.13 C NMR spectrometry was used to identify the mechanism of crosslinking reaction through esterification of hydroxyethyl acrylate (HEA) and 2-hydroxypropyl acrylate (HPA) with carboxylic acid group in acrylic acid-ammonium acrylate copolymerization, but efficiency of crosslinking reaction by esterification was lower than that of copolymerization of vinyl group in crosslinking agent. The Q of acrylic acidpotassium acrylate copolymer of SAHG reaches 1592 mL/g under the following conditions: degree of neutralization of acrylic acid is 80%, content of Irgacure 651 is 0.25 wt %, content of HEA is 0.2 wt %, and exposure time is 10 min.

Synthesis of high efficiency amidoxime polymer adsorbents for uranium extraction from seawater by radiation-induced polymerization

“…For the crosslinker concentration of 2 g, the polymer gel has more crosslinking points to form tree-dimensional network, impeding seawater diffusion into the inside of the polymer gel, resulting in less uranium uptake as well [52]. These results conform with Flory's theory [57] and previous studies [47,52,58].…”

Photolithography with polymethyl methacrylate (PMMA)

“…Irgacure, like other similar aromatic carbonyl compounds, works by photo-induced homolytic cleavage of C-C bonds to generate highly reactive free radicals, as seen in figure 1 [29]. Under UV exposure it releases methyl radicals which being small possess high diffusivity and thus act as highly efficient photo-initiators [30].…”