3.1.3. The interactions between the mixed surface and water
The total interaction energy GLW–ABSWbetween the mixed sur-face equals the sum of LW interaction free energy GLWSWand Lewisacid–base (AB) interaction free energy . According to Eqs. (S4)and (S5) presented in supplementary materials, the relationships between the solid–liquid interaction free energy and the amountof additive in aqueous medium are shown in Fig. 2.As demonstrated in Fig. 2, the addition of CaCO3 has little impacton LW interaction free energy but increases AB interaction free energy, which results from the significant increase of Lewis base component. As a result, there is a remarkable rise in the total inter-action free energy, which implies that the attraction force between mixed surface and water increases and the hydrophilicity of plastic surface is improved. However, the solid–liquid interactionsin crease with increasing of the amount of DnOP, which is owing to that the addition of DnOP reduces the total surface free energy.Furthermore, the negative value of the solid–liquid interactionsindicates that the interaction force between the mixed surface and water are attraction forces. And thus the attraction force between mixed surface and water decreases and the hydrophobicity of plastic is improved.