A SPECTROSCOPIC STUDY OF DOMAIN ORDERING IN DIACETYLENE-CONTAINING MODEL POLYURETHANES

Raman spectroscopic and visible absorption studies have been conducted to characterize the phase separation behavior of a model polyurethane containing poly(tetramethylene oxide) soft segments and reactive diacetylene units in methylenebis(p-phenyl isocyanate) (MDI) hard segments. Although the degree of phase separation is similar for samples cast from different solvents, perfection associated with intermolecular chain-chain packing in hard-segment domains was found to differ markedly. Crosspolymerizable diacetylene units were incorporated within the hard domains as chain extenders and used to monitor the degree of packing order, since their polymerization kinetics are strongly dependent on segmental packing. Visible absorption spectra as well as frequency shifts in Raman-active vibrations have been interpreted to be associated with different crystalline regions of poly(diacetylenes) connected to the MDI hard segments.