1H T1ρ based ROSY: NMR spectral fingerprints for nanoscale phase separated structure of block copolymers

A nuclear magnetic resonance (NMR) fingerprinting method for nanoscale phase-separated block copolymers (BCPs) consisting of hard and soft segments is introduced. The separation of 13 C spectra is performed using 1 H longitudinal relaxation time in rotating frame ( T 1ρ H )-based ROSY (Relaxation Ordered SpectroscopY) method which uses an inverse Laplace transform of the relaxation time dimension. The method was first validated on a model sample, poly(3-hexylthiophene) (P3HT), as a well-characterized system analogous to phase-separated BCP consisting of soft and hard segments. Then, the method was applied to a class of BCPs, polyurethane. The basic set of solid-state NMR experiments, 13 C direct-polarization magic angle spinning (MAS) obtained with short recycling delays and cross-polarization MAS, which provide 13 C NMR spectra of the mobile and rigid components, respectively, often fail to separate the 13 C NMR spectra of soft and hard segments of BCP. On the other hand, the ROSY separates the 13 C NMR spectra of BCP consisting of nanophase-separated soft and hard segments into their respective segments. This method is useful not only for structure determination of hard and soft domains but also as spectral fingerprinting. Graphical abstract