Efeitos do tratamento com plasma na molhabilidade e rugosidade do poli (ácido lático) - PLA obtido por impressão 3D

Abstract

The growing use of polymers, due to its facility and large scale of production, has popularized these materials in several sectors. Among those, poly (lactic acid) stands out as a versatile and sustainable polymer. PLA is a thermoplastic biodegradable and biocompatible polymer used in several areas, such as in the medical area. Besides that, it has mechanical characteristics similar to oil derivates polymers, with high elasticity modulus, thermoplastic behavior, stiffness and ductility. Due to its properties, it can go through modifications, being it from 3D printing or when submitted to treatments like plasma. 3D printing is a production process that works from a 3D computational model, which can generate different roughness on materials. Plasma, composed of ions, electrons and chemically active species, can react with PLA’s surface, altering its molecular structure and surface energy by the incorporation of functional groups. With these changes it is possible to modify polymer properties, like roughness and wettability. This way, the objective of this work is to evaluate topographic and physical-chemical properties alterations caused by plasma treatment. PLA samples were printed in two groups, the first group with extrusion width of 0,28 mm, and the second one with 0,60 mm. Following, plasma treatment with 90% Ar and 5% O2 using a plasma reactor with radiofrequency source inductively attached was applied for 60 seconds. The wettability measurements were performed in an adapted stereoscope at 4 different intervals and measured on both sides of the drop applied. Finally, treated groups and controls were submitted to optical profilometry and scanning electron microscopy. The roughness encountered was bigger for the 0,60 mm samples, pointing to an influence of printing parameters. The same relation was found for treated samples in relation to control. Besides that, plasma treatment has been shown to be efficient on the wettability increase for the first interval measured (0h) in 0,28 mm samples, while the 0,60 mm group has obtained inconclusive results. Nonetheless, the contact angle measurement at later intervals showed a tendency to hydrophobic recovery on the 0,60 mm group, that was not observed for the 0,28 mm group. Therefore, with the increase of roughness and subsequent increase of wettability, this study concludes that plasma treated PLA shows characteristics that are compatible with the characteristics of a biomaterial.