Hemicellulose and lignin densely packaged around the cellulose diffuse with coefficients in the range of 2-6× 10 -9 cm 2 /s, with the slowest diffusion occurring for the least solvated structures, consistent with what has been seen previously. Polymer acetylation increases polymer molecular weight, which would be expected to decrease diffusion based on prior biopolymer diffusion measurements. The low impact of acetylation on diffusive behavior with a high water content (expanded system) is consistent throughout our analysis of Fig. , where monovalent cation diffusion (Na + ) is 2.5 × 10 -7 cm 2 /s for a fully acetylated cell wall model, which is only modestly slower than 6.1 × 10 -7 cm 2 /s for an unacetylated simulation. By constrast, when water is removed upon acetylation, the equivalent diffusion coefficient is approximately 6.2 × 10 -8 cm 2 /s Fe 3+ diffuses much more slowly, at rates similar to the lignin and hemicellulose, with measured diffusion coefficients of approximately 5 × 10 -9 cm 2 /s.