ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

¹H T_1ρ based ROSY: NMR spectral fingerprints for nanoscale phase separated structure of block copolymers

Koji Yazawa, Naoki Asakawa, and Yusuke Nishiyama

JEOL RESONANCE Inc., Akishima, Japan

E-mail: kyazawa@jeol.co.jp

Received: 8 April 2022  Accepted: 17 August 2022

Abstract:

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 ¹³C spectra is performed using ¹H 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, ¹³C direct-polarization magic angle spinning (MAS) obtained with short recycling delays and cross-polarization MAS, which provide ¹³C NMR spectra of the mobile and rigid components, respectively, often fail to separate the ¹³C NMR spectra of soft and hard segments of BCP. On the other hand, the ROSY separates the ¹³C 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

Keywords: Block copolymer; Nanoscale phase separation; Spectral fingerprint; Solid-state NMR; Spin diffusion; ROSY; T 1ρ

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-022-02441-4

Chemical Papers 76 (12) 7783–7792 (2022)