Polyurethanes (PU) are widely used in defense applications such as high performance coatings and other engineered materials due to their versatility and durability. In situations where chemical contamination is a concern, a fundamental understanding of the chemical interactions that result from chemical species absorption into PU plays a key role in the development and optimization of decontamination formulations as well as coatings materials for increased chemical resistance. In this contribution, we explore the chemical mechanisms responsible for the enhanced extraction of a hydrogen bonding penetrant (2,5-lutidine) from PU films using aprotic and protic solvents. The chemical interaction between the solvent, penetrant, and polymer functional groups are characterized via time-resolved FTIR spectroscopy. Inspection of the FTIR spectra reveals two potential mechanisms that facilitate the enhanced desorption rate: (1) penetrant/solvent competition for hydrogen donor groups on the polymer backbone and (2) disruption of the self-interaction (cohesive forces) between neighboring polymer chains. Finally, the aprotic solvent is found to generate an order of magnitude greater desorption rate of the penetrant, which is attributed to a greater disruption of the self-interaction during penetrant desorption in comparison to the protic solvent and the inability for an aprotic solvent to form larger and potentially slower penetrant-solvent complexes.

Multicomponent transport and extraction of chemical species in polyurethane

256th National Meeting (2018)

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