SOLID-STATE C-13 NUCLEAR-MAGNETIC-RESONANCE CHARACTERIZATION OF MDI-BASED POLYURETHANES

C-13 solid-state nuclear magnetic resonance (NMR) experiments on linea r polyurethanes and poly(ether-urethane) block copolymers demonstrate that C-13 spin-lattice relaxation experiments in the laboratory [T1 (C )] and rotating [T1rho(C)] frames provide the most information about d omain morphology in these microphase-separated polymer systems. T1 (H) , T(CH), and T1rho(H) data are less useful. In a 4,4'-methylene bis (p -phenyl isocyanate) -1,4-butanediol (MDI/BD) hard-segment material, th e MDI bridging methylene and the MDI urethane carbonyl T1 (C) and T1rh o(C) times fall in characteristic ranges for crystalline, amorphous, i nterfacial, and dissolved species. BD methylene carbons have short T1r ho(C) for crystalline and long T1rho(C) for amorphous hard-segment agg regates. The distinct T1rho(C) and T1(C) fractions observed are attrib uted to the presence of several crystalline polymorphs. Both T1(C) res ults and DSC endotherms indicate that the crystalline polymorphs prese nt in the poly(ether-urethane) are less ordered than the types seen in the pure hard-segment material. (C) 1993 John Wiley & Sons, Inc.