## 3 Results and Discussion  
To show the position and arrangement of acrylic acid and sodium acrylate in relation to the montmorillonite layer, the carbon quantity contour maps and graphs of the number of atoms belonging to acrylic acid, sodium acrylate, and Na\({}^{+}\) as a function of distance from the montmorillonite layer surface were made. The carbon quantity contour maps and quantity of atoms belonging to acrylic acid as a function of distance from the montmorillonite layer in 36.35, 52.90, and 63.00 ps after adding acrylic acid are shown in Figure 3. The contour map for 36.35 ps clearly shows the grouping of carbon atoms that make up the acrylic  
Figure 2: (**a**) Unit call of montmorillonite structure reported in [17], (**b**) a small fragment of initial (before simulations) montmorillonite layer built on the base of the unit call presented in (**a**), (**c**) acrylic acid molecule, and (**d**) acrylic anion based on structured data from [18]. acid molecules (Figure 3a). Similar groupings are visible for 52.90 and 63.00 ps. The atom quantity graphs as a function of distance from the surface of the montmorillonite layer (Figure 3b) show that the atoms that make up acrylic acid and Na\({}^{+}\) are grouped at distances up to 16.0(3) A. Nearest to the surface of the layer are hydrogens atoms from the COOH group (H\({}_{\text{COOH}}\)) at 1.2(3) A and hydrogens bonded to carbon (H\({}_{\text{AA}}\)) a bit further at 1.5(3). These atoms are much closer than the positively charged Na\({}^{+}\) compensating for the negative charge of the layer, which is the most frequent at about 3.5 A. The oxygen molecules from the COOH group (O\({}_{\text{COOH}}\)) are located a little further from the surface at about 2 A. This shows that the molecules closest to the surface are directed to the surface with H\({}_{\text{COOH}}\) and H\({}_{\text{AA}}\). Both contour maps and graphs of the number of atoms in the dependence of distance from the montmorillonite surface show little changes over time in the position of the atoms groupings and the arrangement of the atoms within the group. These changes are caused by the random thermal movement of the water molecules. Figure 3: _Cont._  
The simulations showed that acrylate anions do not tend to group. Carbon quantity contour maps (Figure 4a) show the scattered groupings of carbon atoms that correspond to single acrylate anions. There is a maximum of 3 carbon atoms. Na\({}^{+}\) cations are nearest to the montmorillonite surface (Figure 4b). Only at above 4 A from the surface do the atoms building acrylate anions begin to appear. Figure 3b shows neither sodium nor the atoms building acrylate ions grouped close to the surface. Both Na\({}^{+}\) and acrylate anions are present far from the surface, above 20 A in the bulk of the water, as well as a short distance from the surface. The presence of sodium cations far from the surface is due to the presence of CH\({}_{2}\)=CHCOO\({}^{-}\) balancing the charge of Na\({}^{+}\). To describe the surroundings of oxygen atoms bonded to Si (O\({}_{\text{Si}}\)) on the surface of the montmorillonite layer, radial distribution functions (RDF) of O\({}_{\text{Si}}\)-I atom pairs were prepared. Figure 5 shows the RDF functions of O\({}_{\text{Si}}\)-H\({}_{\text{COOH}}\), O\({}_{\text{Si}}\)-H\({}_{\text{AA}}\), O\({}_{\text{Si}}\)-O\({}_{\text{COOH}}\), O\({}_{\text{Si}}\)-C\({}_{\text{COOH}}\), and O\({}_{\text{Si}}\)-Na\({}^{+}\) atoms averaged over time, ranging from 62 to 63 ps, after adding acrylic acid (Figure 5a) and O\({}_{\text{Si}}\)-Na\({}^{+}\), O\({}_{\text{Si}}\)-H\({}_{\text{NAA}}\), O\({}_{\text{Si}}\)-O\({}_{\text{COOH}}\)-, and O\({}_{\text{Si}}\)-C\({}_{\text{COOH}}\)- after adding sodium acrylate (Figure 5b). The sharp peaks of the RDF function for O\({}_{\text{Si}}\)-H\({}_{\text{COOH}}\) occur for distances from 1.40 A to 2.16 A (mean 1.75 A). This distance range corresponds to the distances between the O\({}_{\text{Si}}\) and neighboring H\({}_{\text{COOH}}\) atoms.