Process for preparing bromine- containing polymers

Abstract

The invention provides a process for preparing bromine-containing polymers, comprising a Friedel-Crafts alkylation reaction of pentabromobenzyl halide with a polymer reactant which contains one or more six-membered aromatic ring(s) in its repeat unit, in the presence of at least one Friedel-Crafts catalyst. The so-formed bromine-containing polymers, having pendent —CH2C6Br5 groups attached to at least a portion of the six-membered aromatic rings of the polymer, with a carbon ring atom of said six-membered aromatic ring being bonded to the aliphatic carbon of said —CH2C6Br5 pendent group, are also provided. These bromine-containing polymers are useful as flame retarding agents.

1 . A process for preparing bromine-containing polymers, comprising a Friedel-Crafts alkylation reaction of pentabromobenzyl halide with a polymer reactant having one or more six-membered aromatic ring(s) in its repeat unit, wherein said reaction takes place in a solvent in the presence of at least one Friedel-Crafts catalyst. 
     
     
         2 . A process according to  claim 1 , wherein the pentabromobenzyl halide is pentabromobenzyl bromide. 
     
     
         3 . A process according to  claim 1 , wherein the polymer starting material is represented by Formula III or Formula IV: 
       
         
           
           
               
               
           
         
         wherein in Formula III, R is a linear or branched aliphatic chain or bromine; k is independently an integer from 0 to 4; A is selected from the group consisting of null, —CH 2 CH 2 —, —CH 2 CH═CHCH 2 —, —CH(CH 3 )CH 2 — and —CH 2 —CH═C(CH 3 )CH 2 —; n and m are the number of units in the polymer chain; 
         and wherein in Formula IV, X is selected from the group consisting of null, O, S, —CH 2 —, —CH 2 CH 2 —, and n is the number of units in the polymer chain. 
       
     
     
         4 . A process according to  claim 3 , wherein the polymer starting material is either a polymer of Formula III, with k=0, A=null and m=0 (polystyrene) or a polymer of Formula IV, with X═O (poly(phenylether)). 
     
     
         5 . A process according to  claim 4 , comprising charging a reaction vessel with a solvent, a polymer starting material which is polystyrene, pentabromobenzyl halide and one or more catalysts used for Friedel-Crafts alkylation, allowing the Friedel-Crafts alkylation to reach completion and recovering bromine-containing polystyrene having pendent —CH 2 C 6 Br 5  groups. 
     
     
         6 . A process according to  claim 1 , wherein a mixture of AlCl 3  and SnCl 4  is used to catalyze the reaction. 
     
     
         7 . A process according to  claim 1 , further comprising a step of subjecting the so-formed pentabromobenzyl-substituted polymer to bromination reaction.