Radical Grafting from Carbon Black. Graft Polymerization of Vinyl Monomers Initiated by Peroxyester Groups Introduced onto Carbon Black Surface

Abstract

Carbon blacks having tert-butyl peroxyester groups (1, 2, and 3) were prepared by the reaction of acyl chloride CB-COO -t-Bu II 0 CB-O-C(CH2) 4 ~-OO-t-Bu 0 2 yH3 CB-y-(CH2)i-~-OO-t-Bu CN 0 3 groups on carbon black with tert-butyl hydroperoxide. The introduction of acyl chloride groups onto carbon black was achieved by three methods: (I) reaction of a carboxyl group with thionyl chloride, (2) reaction of a phenolic hydroxyl group with adipoyl chloride, and (3) reaction of thionyl chloride with a carboxyl group introduced by the treatment of aromatic ring of carbon black with 4,4'-azobis(4-cyanovaleric acid). Carbon black 1 has no ability to initiate the graft polymerization of methyl methacrylate (MMA) because phenyl radical formed on the carbon black by decomposition of the peroxyester groups inhibited the polymerization. On the contrary, carbon blacks 2 and 3 were able to initiate the graft polymerization of MMA at 70-90°C and PMMA was effectively grafted onto the surface based on the propagation of the polymer from the alkyl radicals formed on the surface. The percentage of grafting of PMMA at 70°C by use of 3 as initiator increased to about 80% with progress of polymerization. Furthermore, the graft polymerization of several vinyl monomers initiated by 3 was investigated. KEY WORDS Carbon Black / Graft Polymerization / Polymer-Grafted Carbon Black / Peroxyester Groups / 4,4'-Azobis(4-cyanovaleric acid) / Methyl Methacrylate / tert-Butyl Hydroperoxide / 214 CB-R-fCH 2-CH1 CH 2-CH I n-I

Surface Grafting of Polymers onto Nanoparticles in a Solvent-Free Dry-System and Applications of Polymer-grafted Nanoparticles as Novel Functional Hybrid Materials

“…[7][8][9][10]35,36 During the polymerization in organic solvents, it was confirmed that the grafted polymer chains propagate from the surface radicals formed by the thermal decomposition of azo and peroxyester groups introduced onto the surface. Therefore, we designed the radical graft polymerization of vinyl monomers from silica nanoparticle surface initiated by azo and peroxycarbonate groups in a solventfree dry-system.…”

“…[4][5][6][7] This suggests that polymerization can be initiated by both surface radicals and fragment radicals formed by the thermal decomposition of the surface azo groups: the surface radicals produce surface-grafted polymer, but the fragment radicals produce ungrafted polymer, as shown in Scheme 4. It is thought that during the final stage of graft polymerization, the latter reaction proceeds preferentially, resulting in a decrease in grafting efficiency.…”

“…We have pointed out that the dispersibility of silica nanoparticles, carbon black, and carbon nanotubes is extremely improved by surface grafting of polymers, namely, chemical binding of polymers, onto silica nanoparticles, carbon black, and carbon nanotube surfaces. [1][2][3][4][5][6] We have reported grafting of various polymers, such as vinyl polymers, [7][8][9][10] polyesters, 11,12 polyethers, 13,14 poly(organophosphazene), 15 polyurethane, 16 and poly-(dimethylsiloxane), 17 onto the surface of silica nanoparticles and carbon black using surface functional groups as grafting sites. Furthermore, many other researchers have also attempted to graft polymers onto silica nanoparticle and carbon black surfaces.…”

Polymer Grafting onto Carbon Black by Solid State Method

“…Tsubokawa et al have reported that polymer radicals formed by the thermal decomposition of azo polymers 8 and peroxide polymers 9 are effectively trapped by polycondensed aromatic rings of the CB surface to give the corresponding polymer-grafted CB. Therefore, the grafting reaction of the CB surface with NR radicals formed by the thermal dissociation was examined in this paper.…”

“…The second is ''grafting from'' which involves surface initiation then subsequent polymer grew from the surface. Tsubokawa and co-workers [8][9][10] have reported some other methods to graft polymer by CB surface trapping polymer radicals which was formed by thermal decomposition of some polymers such as azo, peroxide polymer and so on.…”