Intermolecular interaction between macromolecules of polymethacrylic acid and polyaniline in a polymer composite

Abstract

The quantum-chemical calculations of macromolecule fragments of polymethacrylic acid (PMAA), polyaniline (PANI), and composites based on these polymers are carried out. Semi-empirical calculations for polymer fragments of PMAA (8 units) and PANI (4 protonated units) and their compositions were performed using the MOPAC2016 and the WinMostar graphical interface, using the method of PM7, taking into account dielectric water permeability (EPS = 78.4) as a solvent. Thermodynamic calculations of models were performed using the key parameter THERMO (290,330,10). X-ray studies of output polymers and composites with different content of PANI are carried out. X-rays PMAA and PANI differ, and in spectra of composites based on these components, there are new peaks. Some of the peaks are shifted in comparison with peaks of pure components. This fact indicates intermolecular interaction between macromolecules of different types. The calculated values of heat of formation ( Δ f H o ) for the composite are smaller values for the sum of the corresponding values of the fragments of the studied polymers. Reducing energy Δ f H o is associated with the formation of hydrogen bonds between PMAA and PANI fragments. The difference between the corresponding values of Δ f H o is around 40 kJ/mol; it corresponds to the formation of 3–4 intermolecular hydrogen bonds to a certain fragment. The total heat capacity of PMAA and PANI is smaller than the heat capacity of the composite with the same composition of the fragments. The difference between the corresponding values is ~ 10 J/mol . К. It is shown that intermolecular hydrogen bonds are formed between macromolecules. The formation of hydrogen bonds affects the physic-chemical properties of the resulting composites. Keywords: composites, polymethacrylic acid, polyaniline, quantum-chemical calculations, intermolecular interaction, hydrogen bonds.