摘要:
Cyclic oligomers containing ester linkages are polymerized in the presence of a catalyst having at least one oxygen atom bonded to two metal atoms. At least one of the metal atoms is a tin atom, which is preferably tetravalent, i.e., bonded to three other groups in addition to the oxygen atom. The other metal atom may also be another tin atom, which is again preferably tetravalent, or a zinc, aluminum or titanium atom. The catalyst may contain multiple oxygen atoms that are bonded to two such metal atoms as described. These catalysts are active, efficient polymerization catalysts. They are often liquids at polymerization temperatures. The catalysts can be formed in situ in the polymerization process, which provides additional flexibility in the process and increased storage stability of starting materials.
摘要:
A process and catalyst for the hydro-oxidation of an olefin having three or more carbon atoms, such as propylene, to form an olefin oxide, such as propylene oxide. The process involves contacting the olefin with oxygen in the presence of hydrogen and a hydro-oxidation catalyst under reaction conditions; the catalyst comprising gold nanoparticles deposited on a nanoporous titanium-containing support, prepared by depositing a gold-ligand cluster complex onto the support to form a catalyst precursor, and then heating and/or chemically treating the catalyst precursor to form the hydro-oxidation catalyst composition. The hydro-oxidation catalyst exhibits stabilized catalyst activity, enhanced lifetime, and improved hydrogen efficiency.
摘要:
A process and catalyst for the hydro-oxidation of an olefin having three or more carbon atoms, such as propylene, to form an olefin oxide, such as propylene oxide. The process involves contacting the olefin with oxygen in the presence of hydrogen and a hydro-oxidation catalyst under reaction conditions; the catalyst comprising gold nanoparticles deposited on a nanoporous titanium-containing support, prepared by depositing a gold-ligand cluster complex onto the support to form a catalyst precursor, and then heating and/or chemically treating the catalyst precursor to form the hydro-oxidation catalyst composition. The hydro-oxidation catalyst exhibits stabilized catalyst activity, enhanced lifetime, and improved hydrogen efficiency.
摘要:
The invention is a photoswitchable benzocyclobutene-based polymer that while remaining aqueous developable, avoids the problem of significant moisture uptake. The oligomer or polymer comprises a polymeric backbone, benzocyclobutene reactive groups, and photoswitchable pendant groups. The pendant groups are bonded to the polymeric backbone and are characterized by the presence of a moiety that converts to carboxylic acid upon exposure to activating wavelengths of radiation a carboxylic acid. When the oligomer or polymer is subsequently heated to cause cure of the oligomer or polymer, carbon dioxide is emitted and the group forms a substantially non-polar moiety. The invention is also a method of making such a polymer and a method of forming a patterned film using such a polymer.
摘要:
The invention is a photoswitchable benzocyclobutene-based polymer that while remaining aqueous developable, avoids the problem of significant moisture uptake. The oligomer or polymer comprises a polymeric backbone, benzocyclobutene reactive groups, and photoswitchable pendant groups. The pendant groups are bonded to the polymeric backbone and are characterized by the presence of a moiety that converts to carboxylic acid upon exposure to activating wavelengths of radiation a carboxylic acid. When the oligomer or polymer is subsequently heated to cause cure of the oligomer or polymer, carbon dioxide is emitted and the group forms a substantially non-polar moiety. The invention is also a method of making such a polymer and a method of forming a patterned film using such a polymer.