Synthesis and characterization of ordered polyurethanes from tolylene 2,4-diisocyanate and ethylene glycol

An ordered polyurethane with a head-to-head or tail-to-tail (H-H or T-T) co ntent of 90% was prepared by polyaddition reaction of a nonsymmetric monome r, tolylene 2,4-diisocyanate (1) with a symmetric monomer, ethylene glycol (2). The polymerization was conducted in toluene in the presence of dibutyl tin dilaurate (DBTL) at 0 degreesC by slow addition of a half amount of 2 t o 1, followed by removing toluene and then adding the rest of 2 in DMF at o nce at room temperature in the presence of DBTL. Furthermore, the authentic ordered and random polymers were prepared to verify the structure of the o rdered polymer and it was found that the polymer had the expected structura l regularity, The constitutional regularity of polymers influenced on their thermal properties.