Externally stimulated initiator systems for cationic polymerization

The application of FT-IR and high resolution solid state NMR to the structural characterization of epoxies is described. Theoretical and experimental background is given and progress to date in these two fields summarized.

Application of FT-IR and NMR to epoxy resins

Preparation of Cyclic Carbonates from Oxiranes and Carbon Dioxide in the Presence of Bifunctional Catalysts



Mixtures of metal halides and alkylammonium iodides catalyze the synthesis of cyclic carbonates 2 from oxiranes and carbon dioxide at room temperature and atmospheric pressure. The chemoselective reaction proceeds smoothly with mono-substituted oxiranes while 1,2-disubstituted substrates are inert. By the use of chiral oxiranes the reaction opens a simple access to chiral carbonates like (R)- and (S)-4-(chloromethyl)-1,3-dioxolan-2-one (2c). Insertion of carbon dioxide into the CO bond occurs with retention of configuration and with optical yields of 73 – 98%.

Bifunktionelle Katalysatoren zur Synthese cyclischer Carbonate aus Oxiranen und Kohlendioxid

The present invention relates to a process for the alkoxylation of organic compounds comprising the reaction of at least one organic compound with at least onealkoxylating agent in the presence of a catalyst system, wherein a polyetheralcohol is obtained. The catalyst system comprises a metallo organic framework mate-rial comprising pores and at least one metal ion and at least one at least bidentate organic compound, which is coordinately bounded to said metal ion. Furthermore it relates to polyurethanes or polyurethane foams, which are obtainable by using a prepared polyether alcohol as a starting material.

Process for the alkoxylation of organic compounds in the presence of novel framework materials

Silicone–epoxy resins were synthesized through hydrosilylation of 1,2-epoxy-4-vinyl-cyclohexane with 1,3,5,7-tetramethycyclotetrasiloxane. The silicone–epoxy resins showed high reactivity in the presence of aluminum complex/silanol compound catalysts. Curing of the resins was effected at extremely low concentrations of the aluminum acetylacetonate/Ph2Si(OH)2 catalyst to give hard materials with optical clarity. For the silicone–epoxy resins containing SiH bonds, Al(acac)3 alone is effective for the curing. The cured silicone–epoxy resins showed excellent UV resistance. An improvement in the lifetime of UV-LEDs was achieved using the silicone–epoxy compositions as encapsulant. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3954–3959, 2007

Studies on UV-stable silicone–epoxy resins

The polymerization of cyclohexene oxide was investigated with a new catalyst system of Al(acac)3- silanol compounds. Catalyst activity varied with the ratio of silanol/Al(acac)3 and the structure of silanol compounds. Catalyst deactivation appeared to be caused by self-condensation of silanol and the addition of silanol to the epoxy ring. Polymer structure was investigated by 13C-NMR spectroscopy and x-ray diffraction. The mechanism of the polymerization appears to be cationic.

Polymerization of cyclohexene oxide with Al(acac)3‐ silanol catalyst

Polymerization of cyclohexene oxide, especially the catalytic activity influenced by silanol structure, was examined by using an Al(acac)3–silanol compound catalyst. The catalytic activity increased as the acidity of silanol increased. It was prolonged by sterically hindered silanol compounds which prevented the silanol from self-condensation and from joining with the epoxide. In addition, the greater catalytic activity produced by intramolecular hydrogen-bonding silanol compounds is explained by the polymer effect.

Polymerization of cyclohexene oxide with aluminum complex‐silanol catalysts. Part III. Dependence of catalytic activity on bulkiness of silanol and its intramolecular hydrogen bond

The polymerization of cyclohexene oxide with Al(acac)3-silanol catalyst supported by zeolite and porous silica has been investigated. Cyclohexene oxide was also polymerized to a lesser extent by a zeolite-silanol catalyst and an Al(acac)3-silica gel catalyst. The catalytic activity of the zeolite-silanol system varied with the zeolite pore size. The catalytic activity of the Al(acac)3-silanol system was enhanced by supporting the catalyst with porous silica or zeolite. The Al(acac)3-silanol catalyst supported by zeolite was especially effective in increasing polymer conversion and molecular weight. Catalytic activity increased with increasing chemical interaction between silanol and porous silica. The molecular weight of the polymers with these catalysts increased in the order zeolite-silanol> zeolite-Al(acac)3-silanol >Al(acac)3-silanol ≈ Al(acac)3-silanol supported by porous silica>Al(acac)3-silica gel.

Polymerization of cyclohexene oxide with Al(acac)3‐silanol catalyst supported by zeolite and porous silica

Polymerization of cyclohexene oxide with aluminum complex-silanol catalyst. IV. Photopolymerization with Ph3SiCOPh-Al complex-alcohol catalyst system

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Polymerization of cyclohexene oxide with Al(acac)3‐ silanol catalyst

Polymerization of cyclohexene oxide with aluminum complex‐silanol catalysts. Part III. Dependence of catalytic activity on bulkiness of silanol and its intramolecular hydrogen bond

Polymerization of cyclohexene oxide with Al(acac)3‐silanol catalyst supported by zeolite and porous silica

Polymerization of cyclohexene oxide with aluminum complex-silanol catalyst. IV. Photopolymerization with Ph3SiCOPh-Al complex-alcohol catalyst system