Dynamic Nuclear Polarization Signal Amplification as a Sensitive Probe for Specific Functionalization of Complex Paper Substrates

In this work, it is shown how solid-state NMR combined with dynamic nuclear polarization (DNP) can be employed as a powerful tool to selectively enhance the spectral intensity of functional groups on the surface of cellulose fibers in paper materials. As a model system, a poly(benzyl methacrylate) (PBEMA)-functionalized paper material is chosen that contains hydrophobic and hydrophilic domains. Detailed analysis of the DNP NMR data and of T-1 rho data suggests that inhomogeneous H-1-H-1 spin diffusion is responsible for the observed differences in signal enhancement. These findings are fundamental for structural understanding of complex paper substrates for fluid transport or sensor materials.