Page 20 - PR 2014 2016 03 Applications of Ionizing Radiations

62 Application of Ionizing Radiations | Progress Report

techniques instead of conventional free-radi- RAFT polymerization of GMA revealed the
cal polymerization methods. Among the CRP difficulty of controlling the polymerization
methods, the reversible addition–fragmenta- of GMA due to high crosslinking tendency of
tion chain transfer (RAFT) polymerization is this monomer under γ-irradiation.
considered as advantageous considering its
applicability to most monomers that reacts Polycarbonate chromatography column to be
through radical polymerization, compatibility used in a Mo/ 99m Tc generator irradiated in
99
with various reaction conditions and sim- saline solution with electron beam and gam-
99
plicity of execution compared to competitive ma rays Mo/ 99m Tc generator is a device used
techniques. Glycidyl methacrylate (GMA), has to extract the 99m Tc of decaying Mo. Current-
99
both vinyl and epoxy functions, is a reactive ly, chromatographic column of acid alumina
monomer which can be used for post-polym- (Al O ), principal component of generator, is
2 3
erization modification. Moreover, after the made of borosilicate type 1 glass. The goal of
modification of PGMA, the obtained polymer this study was to characterize irradiated poly-
can be further used for other reactions via carbonate (PC) column in saline solution to
the hydroxyl groups formed in the epoxide mimic a Mo/ 99m Tc generator in real condition
99
ring-opening reaction. Further studies were of use. PC column and samples were electron
performed by Dr. Barsbay adding ethylene- beam and gamma irradiated in saline solution
diamine (EDA), onto cellulose by opening the with radiation absorbed doses up to 200 kGy.
epoxy rings. Amine groups have been known Samples were analyzed by electron paramag-
as one of the most efficient functional species netic resonance (EPR), infrared (FTIR), ultravi-
for removal of toxic heavy metal. The irradia- olet (UV) spectroscopies, differential scanning
tion was performed at room temperature in calorimetry (DSC) and wide-angle X-ray dif-
60
N atmosphere by using a Gammacell 220 Co fraction (WAXD). Additionally, saline solution
2
source at absorbed doses from 2 up to 15 kGy, gamma irradiated in presence of PC column
-1
dose rate of 0.26 kGy h .
RAFT-mediated graft-
ing. The effects of ad-
sorbed dose, monomer
concentration and sol-
vent choice on grafting
yield were investigated
at three different mono-
mer/RAFT agent ratios.
The synthesized copoly-
mers with various graft
ratios were characterized
by ATR-FTIR spectrosco-
py, X-ray photoelectron
spectroscopy (XPS), ther-
mal analysis and scan-
ning electron microscopy
(SEM). Cumyl dithioben- Figure 29. PC phenoxyl radical decay as relative EPR signal intensity at 0.35 T (peak-to-peak) after
time of irradiation. Figure inset shows EPR spectrum of PC gamma irradiated in saline solution,
zoate (CDB) mediated first measurement (considered time=0).

Instituto de Pesquisas Energéticas e Nucleares