To understand the relationship between precursor infusion, film coating thickness and starting TG-101348 structure on the role of ALD on mechanical modification of polymers, we can compare the TEM results in Fig. 2 with the mechanical results in Fig. 4, Fig. 5 and Fig. 6. Considering first the nylon materials, the TEM images in Figs. 2a and d show subsurface growth and a solid film coating after 200 cycles at 50 and 100 °C. The extent of precursor infusion may be larger at lower temperature, but more analysis would be needed to make firm conclusions. The change in modulus upon ALD treatment is the same for coatings at 50 and 100 °C, consistent with similar precursor/polymer reactions, independent of temperature. The ALD process produces a coating and infuses material into the near surface region. Because larger coating thicknesses (> 200 cycles in Fig. 6) do not substantially change the modulus, we can conclude thermacidophiles sub-surface modification is primarily responsible for the increase in film modulus. Longer treatments and thicker coatings reduce necking and promoting sample “snapping”, i.e. brittle fracture, at lower strain values. Under higher strain conditions, the cracking of the ALD overlayer coating could help induce crack formation and propagation in the polymer, leading to the observed decrease in failure strain for the coated samples.