An entirely new, tunable, and scalable
platform (model) approach
for the detailed study of important molecular processes that take
place in geomacromolecular matrices, such as soils, using block copolymer
materials at inorganic interfaces has been developed and applied to
gain a molecular-level understanding of environmental pollutant/soil
interactions. This approach provides a scalable platform with molecular-level
control of the soil organic matter (SOM) chemical composition and
structure, allowing one to examine proposed SOM interactions with
agricultural chemicals (ACs). Accordingly, a series of engineered
soil surrogates (ESSs) utilizing simulated SOM was synthesized, in
which multiblock oligomers were tethered to silica particles, creating
one-, two-, and three-tiered ESSs, via controlled radical polymerization.
Using norflurazon (NOR) as a model AC sorbate for batch mode sorption
experiments, it was found that binding interactions with the ESSs
are not just organic content-driven but are also dependent on the
nature of the chemical structure of an ESS. By a stepwise increase
in the polarity of the second and third tiers, it is shown that the
ability of the ESS to sorb NOR decreases, pointing to a largely hydrophobic
driving force for NOR adsorption to the ESSs. The ESS platform approach
also allows for the investigation of other, more nuanced interactions
with this study, directly showing that hydrogen bonding, electrostatic
interactions, conformation, and π-stacking strongly influence
NOR binding. This approach can also be applied to a range of other
environmentally and agriculturally important issues, such as soil
remediation, microbial community dynamics and evolution, nutrient
cycling, and carbon sequestration, where soil variability between
replicate samples has limited research advances.