The adhesion and stability of hydrophilic polymer thin films prepared from aqueous solutions are of paramount interest in many applications. However, there are very few literature reports on this subject due to the challenging nature of the destabilizing polar interactions during solvent evaporation. In this research, the spontaneous adsorption of poly(vinyl alcohol) (PVOH, 87-89% and 99+% hydrolyzed) from aqueous solutions to silicon-supported trimethylsiloxy terminated polydimethylsiloxane (PDMS) (MW = 340 Da, 2 kDa, and 49 kDa) and tridecafluoro-1,1,2,2-tetrahydrooctyl-dimethylchlorosilane (F13) substrates was carried out. The subsequent desorption and rearrangement of the adsorbed PVOH films in water was investigated to probe the thin film stability. The thickness, wettability, and nano- and macroscopic morphology of the PVOH thin films were studied as functions of substrate hydrophobicity and mobility, PDMS surface coverage, PVOH degree of hydrolysis and concentration, and adsorption time. The PVOH film thickness is found to be strongly correlated with the substrate hydrophobicity. The adsorbed and desorbed PVOH films are discontinuous on all PDMS substrates. The extent of the PVOH film dewetting and desorption significantly increases on the highest molecular weight PDMS<sup>49k</sup> substrate examined. On the other hand, the adsorbed PVOH films are mostly continuous and stable toward desorption on the F13 substrates. Thus far, our results indicate that the characteristics of the adsorbed PVOH films in terms of thickness, morphology, and stability are mostly influenced by the substrate hydrophobicity and mobility.

Investigation of adsorption and desorption of poly(vinyl alcohol) from aqueous solution

ACS Spring 2022

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