Evaluation of the influence of the nature of the substrate on the morphology and properties of modified copolyurethaneimide films by atomic force microscopy

The effect of the substrate nature on the structure and properties of copolyurethaneimide (coPUI) films has been studied using atomic force microscopy (AFM), nanoindentation, and strain-strength testing. It was found that the morphology of the surface of the films of coPUI (R-2300TDI-R)(SODp) is more homogeneous than coPUI (R-AltTDI-R)(SODp). The films are characterized by extremely low rigidity (elastic modulus – 3.6–3.7 MPa, strength – below 4 MPa). Using the nanoindentation method, it was found that the first coPUI has two phases simultaneously – one conventionally called “amorphous” ( E = 30–40 MPa), and the second conventionally called “partially ordered” ( E = 10–25 GPa). Microhardness for the coPUI (R-2300TDI-R)SODp is in the range from 2 to 4 MPa. Using AFM it was determined that the highest value of the adhesion force and, accordingly, the specific surface energy is observed in coPUI (R-2300TDI-R)(SODp). Mechanical tests were carried out and the deformation curves of the coPUI films deposited on different substrates were obtained. It is shown that the morphology and degree of surface roughness of films that were in contact with the substrate during the preparation process significantly depend on the nature of the substrate. The synthesized materials can be used in creation of antifriction coatings, membranes for the first-generation separation of aromatic hydrocarbons from liquid mixtures of aliphatic and aromatic hydrocarbons, which is important for petrochemical technology; as membranes for separating nitrogen/carbon dioxide gas mixtures in order to capture carbon dioxide from flue gases of thermal power plants; structural thermoplastics such as polyurethanes for 3D printing, as well as substrates with controlled adhesion to hold microobjects.