Synthesis and properties of new ferrocene-modified urethane block copolymers

Polyurethane polymers are a wide class of materials, ranging from surface c oatings and adhesives to flexible or rigid foams. However, polyurethanes in general are very flammable and produce heavy smoke when burning. As a resu lt of their flammability, there is a great interest in the development of m aterials with improved fire retardance. In this study a series of new ferro cene urethane block copolymers based on diphenylmethane-4,4'-diisocyanate w ere synthesized and their fire retardant behavior studied using thermogravi metric analysis (TGA), differential scanning calorimetry, cone calorimetry, and the oxygen index. Ferrocene-modified block copolyurethanes showed a 40 -80% reduction in peak heat release rate compared to an unmodified sample. In addition, the TGA results showed that ferrocene-modified polymers have h igh thermal stability and ferrocene enhances char formation in air and heli um. The synergistic effect of silicone and phosphorus with ferrocene was al so discussed. The solution electrochemical behavior of ferrocene-containing polymers was studied using cyclic voltammetry. These polymers showed a rev ersible wave at E degrees approximate to 0.771-0.852 V and the electron tra nsfer was diffusion controlled. (C) 2000 Jokn Wiley & Sons, Inc.