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Branched polyphosphonates that exhibit an advantageous combination of properties, and methods related thereto

  • US 6,861,499 B2
  • Filed: 02/24/2003
  • Issued: 03/01/2005
  • Est. Priority Date: 02/24/2003
  • Status: Expired due to Term
First Claim
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1. A method for producing branched polyphosphonates, comprising:

  • placing a molar excess of a phosphonic acid diaryl ester, one or more bisphenols including 2,2-bis(4-hydroxyphenyl)propane, a branching agent, and a phosphonium catalyst into a reaction vessel;

    heating the mixture in the vessel under vacuum to a temperature where phenol beings to distill from the vessel; and

    heating the reaction mixture until the evolution of phenol has stopped.

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