Composites based on polylactide and manganese (III) tetraphenylporphyrin. Influence of concentration on the structure and properties

The bactericidal action of porphyrin has a very promising potential for medical applications. Therefore, composite materials based on L-Polylactide and manganese (III) chloride tetraphenylporphyrin were prepared. The aim of this work was to study the effects of the concentration of tetraphenylporphyrin on the structural features and mechanical properties of these composites. The concentration of the filler in the composites was in the range of 0.1–2 wt%. The sizes of the tetraphenylporphyrin microinclusions (15–40 μm) were determined using optical microscopy. It was found that the phase transition temperatures of polylactide in the presence of tetraphenylporphyrin varied by 1–2 °C, and the crystallinity degree increased by 4–5% in the composites compared with the pure polylactide. Using the method of electron paramagnetic resonance at 70 °C, an increase in the segmental mobility of the polymer matrix was detected as the tetraphenylporphyrin concentration in the composites was increased. The addition of manganese (III) chloride tetraphenylporphyrin complex microinclusions in the composites slightly enhanced the tensile strength and elongation at break of the polylactide matrix. Thus, the effects of the porphyrin manganese complex on the polylactide matrix and the properties of the composites were shown. •Increasing the MnClTPP content extends the degree of crystallinity of the polylactide.•The addition of MnClTPP increases the segmental mobility of the PLA matrix.•A porphyrin complex enhances the mechanical characteristics of the polymer composites.•The resultant composites have potential in biological and medical applications.