Polymerization of cyclohexene oxide with aluminum complex/silanol catalysts. V. A catalytic activity dependence on the aluminum chelate structure

Abstract

The catalytic activity of an aluminum complex/silanol system was found to vary with the aluminum ligand as follows: β‐diketonate < β‐ketoester anion < ortho‐carbonylphenolate. Aluminum complexes with electron donating groups conjugated with a carbonyl group had higher catalytic activity. The catalyst activity correlated with the strength of interaction between the aluminum complex and the silanol; there were two such interaction mechanisms. Cyclohexene oxide was polymerized cationically by the activated proton of SiOH. The activated proton is considered to be similar to Brönsted acid on silica‐alumina catalyst; therefore, the catalyst would be a model of the silica‐alumina catalyst.

Photopolymerization of Epoxides with Platinum(II) Bis(acetylacetonato)/Silane Catalysts

“…We conclude therefore that, during the irradiation of the absorbing Pt(hfac) 2 ) 10 -4 } to the irradiated solution apparently forces the reaction to go further, and the NMR spectra show that all of the platinum complex is converted to a final product. The polymerization also resembles a living polymerization in that, if more monomer is added to the irradiated solution, polymerization continues after a time.…”

Studies on UV‐stable silicone–epoxy resins

“…Aluminum-complex/silanol catalyst was firstly used for curing of cycloaliphatic epoxy resins, through a cationic polymerization mechanism. [15][16][17] However, the catalyst system was sensitive to moisture in the atmosphere, and therefore the cured epoxy-resin usually showed a seriously wrinkled surface.…”

“…17,18 Change of optical transmittance at different wavelength after UV-aging is shown in Figure 2 for the silicone-epoxy resin (m ¼ 3). The UV aging property of anhydride-cured cycloaliphatic epoxy resin ERL-4221 is also shown for comparison.…”

Photoinitiated Cationic Polymerization: Reactivity and Mechanistic Aspects

“…Arene SCHEME 11.20 SCHEME 11.19 [60] complex initiators are convenient for polymerization of only epoxides, which are able to coordinate with iron. In addition to sulfur containing photoinitiators, selenide [69] and organosilane [70][71][72] based photoinitiators were employed to initiate cationic photopolymerization. The photoinitiated cationic polymerization of epoxides by iron complexes is indicated in Scheme 11.21.…”

“…Organosilane-Based Nonsalt Photoinitiators Silanol are also capable of initiating of cationic polymerization of cyclohexene oxide in the presence of aluminum(III) complexes of b-diketones, b-ketoesters or ortho-carbonylphenolate upon UV irradiation or moderate heating (40 C) [70,72]. The initiation mechanism is demonstrated on the example of the triphenylsilanol/tris(ethyl acetoacetate) aluminum system in Scheme 11.23.…”