Thin elastomeric gloves are protective equipment and essential in many occupations. Their value in the health and care sector was demonstrated during the recent Covid-19 pandemic.
Most thin gloves are made from aqueous polymer dispersions, often called a latex, using a dipping process. A hand-shaped mould is dipped into a saturated calcium nitrate solution, followed by oven drying. This coated former is then dipped into the polymer dispersion for a controlled period, known as the dwell time, during which a polymer deposit accumulates. Drying of this deposit, often termed the wet gel, produces an elastomeric film that is peeled from the former to yield the glove product.
A new article published in Soft Matter and co-authored by professor Alex Routh and Dr Robert Groves investigates two possible mechanisms for formation of the deposit during the electrolyte dipping process. The conventional, widely accepted, mechanism proposes that electrolyte on the former diffuses into the compound and a wet gel coagulates where the electrolyte concentration is above a critical coagulation value. An alternative mechanism proposes that deposition occurs via particle movement towards the former, driven by diffusiophoresis.
In this new article, the two mechanisms are examined using dipping nitrile latex and various mono and divalent cation electrolytes. The authors have run laboratory experiments and used them to develop and validate a new model, which suggests that diffusiophoresis likely affects the deposition, but only to a small extent. Interestingly the effect of diffusiophoresis is more pronounced for monovalent electrolytes. You can read the full article here, and read more about the work on thin gloves which is ongoing at the Institute here.