Gum-g-Copolymers: Synthesis, Properties, and Applications - Polysaccharide Based Graft Copolymers - page 168

Fig. 5.15 Mechanism for “microwave-initiated synthesis of PSY-g-PAM” [ 167 ]
The microwave-assisted graft copolymerization in the presence of little (or catalytic
amount of) chemical initiator is another important reaction styles [ 26 , 162 , 163 , 166 ,
170 ]. The main initiator is persulfate and ceric salts. The primary radical can be formed
more effectively under the action of microwave, and the graft efficiency can be
improved to a certain degree. The active radicals formed on the hydroxyl groups of
gum may react with vinyl monomers (i.e., acrylic acid, acrylamide, acrynitrile,
4-vinylpyridine) or non-vinyl monomers (i.e., aniline) to form graft polymers.
Figure 5.16 shows the graft mechanism of aniline onto the AG using APS and MW
as the associated initiation approach. The radical initiator APS was decomposed under
microwave radiation to form a sulfate ion radical, and then the radical stripped down
the H atom of the -OH groups of gum to generate a macroradical. The macroradical
may react with the active PANI chains [ 26 ] to form the graft copolymer.
5.4.3.2 Radiation-Initiated Grafting Copolymerization
Gamma ray is electromagnetic radiation of high frequency and therefore energy.
Gamma rays are ionizing radiation and are classically produced by the decay from
high-energy states of atomic nuclei (gamma decay) but also in many other ways.