Polyurethanes. III. The effects of aromatic rings on the structure and properties of polyurethanes based on ethylene glycol

A series of aromatic polyurethanes based on ethylene glycol and two of their aliphatic analogs were synthesized and some of their physical properties determined. Polymer chain conformations are proposed which are consistent with X‐ray diffraction data. The polyurethane from diaminodiphenylmethane and ethylene glycol has a twisted chain conformation. This is in contrast to other polyurethanes examined which closely resemble their polyamide counterparts. The melting temperatures and glass transition temperatures of the polyurethanes are shown to be affected by chain stiffening resulting from the presence of the aromatic rings, as well as by the conformation of the polymer chains.