Solid-State ¹³C NMR Analyses of the Microphase-Separated Structure of Polyurethane Elastomer

Solid-state 13 C NMR analyses have been performed to obtain information about the microphase-separated structure for polyurethane (PUR) elastomer, which is prepared from p -phenylene diisocyanate (PPDI), poly(tetramethylene oxide) (PTMO), and 1,4-butanediol (BD). 13 C spin−lattice relaxation time ( T 1C ) analyses have revealed that three components with different T 1C values exist for the PPDI and BD residues, while two components are observed for the PTMO carbons. The longest T 1C components of the PPDI and BD carbons are assigned to the crystalline component, whereas the PTMO carbons with shorter T 1C 's and the PPDI and BD residues with shortest T 1C 's are ascribed to the rubbery component. Moreover, the PPDI and BD residues with the medium T 1C values and the PTMO carbons with the longer T 1C values are found to be assignable to the interfacial component by the T 1C measurement for the component selectively created through the 1 H spin diffusion from the rubbery component. The mass fraction values of the three components thus assigned are determined for the respective structural units; in the PPDI units, for example, the mass fraction values 0.40 for the crystalline component, 0.16 for the interfacial component, and 0.44 for the rubbery amorphous component. On the basis of these results, the microphase-separated structure is discussed for the PUR elastomer.