The present invention provides a polymer comprising an aliphatic backbone having a plurality of aromatic rings bonded thereon, said plurality of aromatic rings comprising a first aromatic ring type that has an alkyl halide group substitution on the aromatic ring and a second aromatic ring type that has an optionally substituted ammonium halide group substitution on the aromatic ring. The present invention also provides a method for making an optionally substituted furan, the method comprising the step of subjecting a sugar to a dehydration reaction in the presence of a catalyst comprising said polymer.