. 2023 Sep 18;56(19):2620–2630. doi: 10.1021/acs.accounts.3c00363

Table 1. Approaches Used for Understanding PEI Properties within Mesoporous Silica.

Approach	Characteristics	Accessible PEI properties	Scales (length, time)
Small-angle neutron scattering	Penetrable, contrast (PEI vs silica)	Morphology	0.1–1000 nm^53,54
Quasielastic neutron scattering	Penetrable, selective (PEI mainly)	Mobility (center-of-mass or segmental diffusion)	1 ps–1 ns^55,56
Solid-state NMR (¹H relaxation)	Penetrable, selective (isotopes, spins)	Morphology^a and mobility^a	0.1–100 nm⁵⁷
Solid-state NMR (¹H relaxation)	Penetrable, selective (isotopes, spins)	Morphology^a and mobility^a	ns–ms⁴²
MD simulation	Predict PEI behavior, crosscheck NS and ssNMR results	Morphology and mobility	0.1–100 nm
MD simulation	Predict PEI behavior, crosscheck NS and ssNMR results	Morphology and mobility	1 ps–1000 ns⁵⁸

ssNMR yields qualitative information and trends, whereas NS and MD simulation give quantitative results.