Ion-Specific and Solvent Effects on PDADMA–PSS Complexation and Multilayer Formation

Abstract

Among various parameters that influence the formation of polyelectrolyte complexes and multilayers, special emphasis should be placed on ion-specific and solvent effects. In our study, we systematically examined the above-mentioned effects on poly(diallyldimethylammonium chloride) (PDADMACl)-sodium poly(4-styrenesulfonate) (NaPSS) complexation in solution and at the surface by means of dynamic light scattering, ellipsometry and atomic force microscopy measurements. As solvents, we used water and water/ethanol mixture. The obtained results confirm the importance of ion-specific and solvent effects on complexes prepared in solution, as well as on multilayers built up on a silica surface. The experiments in mixed solvent solution showed that at a higher ethanol mole fraction, the decrease in monomer titrant to titrand ratio, at which the increase in the size of complexes is observed, takes place. The difference between chloride and bromide ions was more pronounced at a higher mole fraction of ethanol and in the case of positive complex formation, suggesting that the larger amount of bromide ions could be condensed to the polycation chain. These findings are in accordance with the results we obtained for polyelectrolyte multilayers and could be helpful for designing polyelectrolyte multilayers with tuned properties needed for various applications, primarily in the field of biomedicine.

Modification of Polydiallyldimethylammonium Chloride with Sodium Polystyrenesulfonate Dramatically Changes the Resistance of Polymer-Based Coatings towards Wash-Off from Both Hydrophilic and Hydrophobic Surfaces

“…The forming coatings represent by itself a continuous film with on average four and six nm thickness on the glass and PVC substrate, respectively. These results are in good agreement with the data obtained for the PSS/PDADMAC bilayers obtained by the layer-by-layer technique of D. Kovačević et al, and the results of simulation for the multilayers from oligo-PSS and oligo PDADMAC by Sanchez et al [ 46 , 47 ].…”

“…As a result, an increase in the ionic strength in IPEC solution could induce phase separation. It should be stressed that different ions may have specific affinity to the charged groups of the polyelectrolytes [ 45 , 46 ]. So, the influence of monovalent and bivalent ions’ concentration on the possibility to form water-soluble PSS/PDADMAC complexes was studied.…”

Quantification of Water–Ion Pair Interactions in Polyelectrolyte Multilayers Using a Quartz Crystal Microbalance Method

“…Taken together, these growth profiles show the influence of salt concentration and salt type on the growth mechanism and growth rate of a PEM. From Figure a,b, it is evident that increasing salt concentration leads to thicker layer pairs, consistent with previous studies. ,− This is because salt screens the charges on the polyelectrolytes, weakening their interactions and changing their conformation from an extended chain to a more coil-like conformation. ,,, As for the salt type, NaCl-assembled PSS/PDADMA PEMs grew more slowly than the KBr-assembled ones, Figure . This is because NaCl is more kosmotropic than KBr, so NaCl is less effective at extrinsic charge compensation, leading to the lower growth rate. , This has previously been reported by experiments and simulations alike, in which the more hydrated ions (Na + , Cl – ) generally bind more weakly to the polyelectrolyte charge sites .…”

Effect of Ethanol and Urea as Solvent Additives on PSS–PDADMA Polyelectrolyte Complexation

“…For ethanol, we conclude that the key to PEM materials scale response is the asymmetric solvation environment, i.e., poor solvation of the ionic groups by ethanol which leads to varying solvent microenvironment around the PEs and consequently enhanced ion condensation. In prior work, this decrease in solvent quality, i.e., increasing the amount of ethanol in assembly solution, has been reported to lead to both film thickness and mass increase. , Here, our QCMD characterization indicated that ethanol addition leads to a decrease of solvent (water + ethanol) in the PEM for PEMs of PSS and PDADMA. The observations indicate that ethanol, because of its polar and apolar ends, is a solvent additive that enables tuning the response by PE chemistry due to the asymmetric solvation character.…”