The complexation of polyelectrolyte by mixing solutions of oppositely charged polyelectrolytes can lead to either solid precipitates orcoacervates. The mechanical properties of these associating polymers depend strongly on the extent of hydration and the fraction of the functional groups participating in the complex (effective crosslinks). Generally, the mechanical properties of polyelectrolyte complexes (PECs) can be modifiedby changes in pH or ionic strength after the PEC is formed, but the changes are limited by diffusion and re-arrangement of the concentrated polymer. This leads to slow response and gradients in properties at short times. In this work, we examine if the salt can be included during the complexation through the formation of three components PECs by one-step complexation. These PECs containweak polyelectrolytes of branched poly(ethyleneimineBPEI) and poly(acrylic acid) (PAA) along with salt, either organic salt, Choline Chloride (ChCl) or inorganic salt, Sodium Chloride (NaCl). Near critical gel viscoelastic fluidPECs areobtainedby one-pot complexation from rheological characteization. The tensile properties of the complex are significantly altered by the inclusion of the salt with a decrease in the Young’s modulus, but significant increase in the extension ratio. TheBPEI/PAA/ChCl complex can be stretched to 11~12 times of its original length.The selection of salt does impact the tensile properties even when the hydration of the complex is identical. Under these conditions, the BPEI/PAA/ChCl complexexhibits a higher Young's modulus and is more stretchable than theBPEI/PAA/NaCl complex. These PECs can be extruded into fibers when hydrated with the salts present.

Influence of salts on the mechanical properties of polyelectrolyte complexes

254th National Meeting (2017)

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