Hyperbranched polymers ceramization

Tang and co-workers have also prepared cobalt-containing hyperbranched polymers by the reaction of cobalt complexes with a preformed hyperbranched polymer 274 containing acetylene groups.321 The percent of cobalt incorporated into the polymers ranged from 27.8 to 36.7 wt %, and upon high temperature pyrolysis, the polymers formed ceramics with magnetic properties. 

Hyperbranched polymers are different from their linear counterparts in architectural dimensionality the former are three-dimensional spheres, whereas the latter are one-dimensional chains. Compared to the chains, the spheres should in principle better retain the constituent elements during the pyrolysis process, leading to the formation of ceramic materials in higher yields. Hyperbranched polymers are also different from crosslinked networks— the former are often soluble, whereas the latter are inherently insoluble. Processibility or tractability is one of the most important advantages of preceramic polymer processes, and the hyperbranched polymers are thus promising precursor candidates for the fabrication of advanced ceramic materials. 

Tang and coworkers have reported that pyrolyzed hyperbranched polyferro-cenylsilanes have greater ceramic yields than their linear polymeric counterparts. Manners has reported that thermally crosslinked polyferrocenylsilanes (28) possessed greater thermal stability than their linear analogs. The swelling properties of these crosslinked polymers were examined, and the solubility parameter of the corresponding linear homopolymer was determined. The pyrolysis of linear, hyperbranched, and crosslinked polyferrocenylsilanes has resulted in the production of ceramics that possess magnetic properties. " ... 

Li et al (2001, 2003) prepared a kind of hyperbranched solid polymer electrolyte with a low ion conductivity of about 10 S/cm at room temperature. Later, they added 10 wt% BaTiOs as ceramic fillers into this SPE, making the ion conductivity rise to 1.4 x 10 S/cm. 

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