Maximizing the reduction of vermiculite monolayers while concomitantly assuring colloidal stability of the obtained nematic suspensions

Vermiculite monolayers are typically two orders of magnitude larger than that of montmorillonite. The material therefore bears great potential for barrier improvement in polymer nanocomposites. Aside from the barrier improvement potential, vermiculite additionally holds promises for accelerating polymer degradation mitigating the microplastic issue. Structural iron will produce reactive oxygen species when submitted to natural anoxic/oxic cycles that have potential to render the surface more hydrophilic, and thus more attractive for colonization by fungi and bacteria. As a first step, here a concomitant optimization of vermiculite delamination, the colloidal stability of the resulting suspensions, and the extent of structural iron reduction, ultimately linked to reactive oxygen species generation, is presented. Delamination of vermiculite by one-dimensional dissolution produced monolayers with a huge aspect ratio of 9000 on average. Delamination, moreover, allows for a substantial increase in reduction with an ascorbate buffer as compared to stacked vermiculite tactoids. While for pristine or restacked Mg- and Na-vermiculite tactoids the reduction level was limited to 28%, the delaminated Li-vermiculite could be reduced to 44% of the total structural iron. This substantial difference is interpreted as indication that electron injections through the edges for delaminated types may be supplemented by injections through the basal planes of delaminated vermiculite. • Delaminated vermiculite nanosheets show high aspect ratios and large surface area. • Delamination strongly promotes structural iron reduction. • Electron transfer occurs through vermiculite basal surfaces. • Reduced vermiculite generates reactive oxygen. • Such fillers can improve barrier performance and accelerate polymer degradation.