Catalytic Behavior of Cobalt (II) Phthalocyanine Immobilized on Bentonite Clay in Bulk Polymerization of Methyl Methacrylate

Abstract

The catalytic behavior of cobalt (II) phthalocyanine (CoPc) immobilized on bentonite clay, with different complex loadings ranging between 0.2 and 2.2 wt%, in the presence of n-butyl amine solvent, was investigated in bulk polymerization of methyl methacrylate without using an activator or cocatalyst. The interaction of CoPc molecules with a bentonite surface, encouraged by the amine, involved the inclined stacking model, i.e., interaction between N-atoms of the macro-ring system and OH's of the support. Two different mechanistic pathway regions could be suggested, depending on complex loadings. The first was in the range, 0.2À1.0 wt% CoPc, behaving in ionic fashion as the bare bentonite. Isolated oriented molecules probably activated bentonite through the exposure of new internal acid sites during intercalation. The second, in the range of 1.4À2.2 wt% CoPc, proceeded via combined mechanisms, ionic functioned by bentonite support and free radical functioned by complex packed oriented stacks, staggered in clay galleries to cover a fraction of internal active acid sites. The number of polymer chains formed per one CoPc center (reaction turnovers) was >2-$10 with diluted catalyst samples. With higher loadings, one chain was formed per active site. Such behaviors, without a detectable effect on polymer characteristics or enchainment sequence, were studied in light of intercalation, orientation and accessibility models.

Various Characteristics of Nanosized V2O5/TiO2and MoO3–Modified V2O5/TiO2Catalytic Systems Used in Redox-Initiated Polymerization of Methyl Methacrylate

“…On the other hand, the polymerization of methyl methacrylate (MMA) has been studied in the presence of some metal oxides and complexes [e.g., [14][15][16][17][18][19][20]. For example, in our previous investigation [14], supported NiO=bentonite clay was found to catalyze the polymerization process anionically, as ions enhanced by nitrite remained in narrower pores of the catalyst system, through decomposition of nickel precursor.…”

Photophysical Properties and Photochemical Activity of Metal Phthalocyanines Adsorbed on Modified Montmorillonite

“…На сегодняшний день в литературе предложено несколько вариантов гибридных органо-неорганических композитов на основе глинистых минералов с адсорбированными металлокомплексами фталоцианина, обладающих как темновой, [17,18] так и фотоиндуцированной каталитической активностью в реакциях окисления различных поллютантов. [15,16,[19][20][21] Для данного вида гетерогенных фотокатализаторов показана возможность проявления фотодинамической активности обоих типов, связанной либо с генерацией синглетного кислорода в результате переноса энергии с фотовозбужденной молекулы ФС на кислород, либо с фотопереносом электрона с образованием АФК.…”