Quantification of dominant diffusion processes through plasma enhanced chemical vapor deposition-coated plastics by combining two complementary methods for porosity analysis

Abstract

Thin plasma polymerized gas barrier coatings were applied on PET films using low-pressure microwave excited hexamethyldisiloxane plasma. Oxygen and water vapor transmission rates were determined for the same barrier coating of varying thickness and correlated with the coating porosity. The porosity was quantified on different scales with two complementary methods. A plasma etching process with subsequent high-resolution SEM imaging and an automated defect detection as well as an overall porosity measurement by means of cyclic voltammetry. This method combination can be used to assign and classify Knudsen diffusion and Knudsen diffusion for different coatings and defect distributions applied. Film growing process could be observed with correlating defect distributions and it could be determined that almost no macro defects with a radius rd > 150 nm are present while growing process. With visually closed coatings, the entire oxygen and water vapor permeation could be attributed to Knudsen and solid body diffusion, although it is difficult to divide the proportions of these two processes.

Advances in surface modification and functionalization for tailoring the characteristics of thin films and membranes via chemical vapor deposition techniques

“…Often, the changes in the pore size also includes the surface pores and thus the surface roughness. Figure 7 shows the changes in the surface morphology of membranes upon variation in the CVD deposition time upon which not only the changes in pore size but also in thickness were noticeable 192 . Figure 6 (c) exhibits the effect of deposition time on contact angle.…”

“…Further reduction in He permeability up to ~25% was possible but required stacking five layers of graphene deposition. In another attempt, Wilski et al 192 employed low pressure PECVD to coat silica on a PET film. Their best membrane showed 96% and 92% decrease in oxygen and water vapor transmission rates, respectively, compared to the neat PET.…”

“…As can be seen in Table 1, there are several studies on the use of PET substrates for CVD, particularly to enhance oxygen and water vapor barrier properties. Specifically, silica and silicon‐based coatings have been applied by CVD which effectively improved the impermeability by more than 90% 142,167,192,215 …”

“…The influence of CVD deposition time on three key characteristics of the coating: (a) coating thickness, (b) pore size, and (c) surface contact angle. 84,171,187,192,200,201,255 [Color figure can be viewed at wileyonlinelibrary.com] dichalcogenides (TMDs) which are a class of materials with growing interests due to their unusual electrical, optical, and mechanical properties. The three-atom thick unit cell of TMDs is created by a layer of transition metal atoms sandwiched between two layers of chalcogen atoms.…”

“…The influence of CVD deposition time on three key characteristics of the coating: (a) coating thickness, (b) pore size, and (c) surface contact angle 84,171,187,192,200,201,255 . [Color figure can be viewed at wileyonlinelibrary.com]…”