UV-irradiation Effects on the Properties of <i>poly</i>-Acrylamide/Sodium Acrylate Gel

Abstract

In the present study, the authors have investigated how the UV-ray irradiation affects the surface condition of wet and dehydrated poly(acrylamide/sodium acrylate) (PAAm/SA) gels. With large amounts of the UV-ray dosage, the wet PAAm/SA gel readily disintegrates to wreak the surface erosion while the dehydrated gel exhibits considerable turbidness in spite of no remarkable change in outline. Besides, even with the smaller dosage spawning no appreciable change only by the UV-ray irradiation, some of the wet PAAm/SA gels turn significantly opaque by putting an aqueous CuCℓ 2 solution on the surface, which indicates the breakup of the surface layer of the wet PAAm/SA gel.

Nano-structural Analyses of Copper-ion-adsorbed PAAm/SA Gels after UV-light Irradiation

“…In addition, a collateral features indicating the surface modification by the UV-light irradiation were also revealed by the phase-contrast microscope investigations of the UV-light irradiated PAAm/ SA gel surface after the cupricion-capturing treatments versus that of the unirradiated surfaces adsorbing Cu: in Fig. 1 The property changes of a UV-light irradiated PAAm/SA gel on adsorbing cupric ion [21]. The phase contrast microscope images of the PAAm/SA gel surface shown in Fig.…”

“…the latter, recognized are the characteristic crinkled patterns (Fig. 2) often emerged in the volume phase transition of the ionized hydrogels; on the other hand, in the former, there are not such a surface structure [1][2][3]21].…”

“…The phase contrast microscope images of the PAAm/SA gel surface shown in Fig. 1(c) across the boundary of UV-ray irradiated and unirradiated areas observed after immersed in CuCℓ2 aqueous solution for 24 hrs [21]. Clear corrugated patterns were observed in the unirradiated area.…”

“…Such a latent change has been thought to have been elicited by the previous macroscopic measurements [21], in which observed was a large decrease in the transmitted light intensity through the Cu 2+ -adsorbed PAAm/SA gels with increasing the UV-irradiation periods: in spite the shapes of the light-transmissivity spectra are not affected so much [21]. In addition, a collateral features indicating the surface modification by the UV-light irradiation were also revealed by the phase-contrast microscope investigations of the UV-light irradiated PAAm/ SA gel surface after the cupricion-capturing treatments versus that of the unirradiated surfaces adsorbing Cu: in Fig.…”

“…Along this line, in the previous study, the authors investigated the effects of the cupric-ion adsorption on the macroscopic and semi-macroscopic properties of the poly(acrylamide/sodium acrylate) (PAAm/SA) gels after the UV-light irradiation for different periods as described below [21]. First, observed were the changes in the macroscopic surface properties of the wet and dehydrated PAAm/SA gels by irradiating UV-light; in spite that the exposed area to the UV-light turns turbid, there was almost no remarkable change in shape even with a large amount of the UV-ray dosage (UV-irradiation for 10 hrs with utilizing a high pressure mercury lamp with 170 mW/cm 2 of output intensity, of which the effective UV wave-lengths are 318 and 365 nm).…”