Effect of Interfacial Regions and Surface Functional Groups on Chemical Transport in Polymer-Particle Composites

AR Hinkle and MA Browe and IO Iordanov and BA Mantooth and TP Pearl and MJ Varady, JOURNAL OF PHYSICAL CHEMISTRY C, 127, 11231-11239 (2023).

DOI: 10.1021/acs.jpcc.3c01379

Improved chemical resistance of polymer-based compositessuch ascoatings remains a significant challenge for many defense applicationsand technologies. In particular, composites with high concentrationsof large, micrometer-size particles present a complex microstructurallandscape of competing processes that influence the transport of penetrantmolecules. We present results of molecular dynamics calculations designedto model micrometer-size particle surfaces that have been modifiedby the addition of functional groups. The effect of the functionalizedsurfaces on the surrounding polymer binder and the diffusive transportof penetrant molecules is examined for different chemistries througha polymer-particle composite system designed to represent aninterfacial region. We directly calculate penetrant diffusion coefficientsand polymer-penetrant properties within the composite interfaceand compare with simulations of the same polymer in bulk systems.In the simulations of the composite interface, the equilibrated polymerdensity is 10-15% less than in the corresponding bulk system,and at room temperature the penetrant diffusivity is found to be morethan an order of magnitude greater in the composite interface. Inthe systems studied here, amine functional groups are seen to haveonly a secondary effect on transport while no change is observed bythe presence of carboxyl groups.

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