Revestimento de polímeros termoplásticos com cerâmicas bioativas para aplicação em implantes ortopédicos: estudo das propriedades mecânicas, químicas e biológicas segundo parâmetros de processamento

Abstract

The growing demand for low-cost, customized orthopedic implants has spurred the development of new technologies for manufacturing and functionalizing biomaterials. This thesis investigated two innovative methods for coating thermoplastic polymers with bioactive ceramics—intermittent compressed air jetting and powder bed annealing—for applications in orthopedic implants produced by additive manufacturing. Both processes were applied to polylactic acid (PLA) parts 3D printed using the Fused Filament Fabrication (FFF) process, evaluating the effects of printing and coating parameters on the mechanical, chemical, and biological properties of the components. Jetting used a continuous flow of hot air combined with intermittent jets of compressed air containing hydroxyapatite (HA) particles, allowing for surface incorporation of the particles. Powder bed annealing consisted of immersing the samples in submicron HA particles and subsequently heating them close to the polymer's melting temperature, promoting adhesion by diffusion. Mechanical tests (flexural, impact, hardness, and rebound hammer), chemical analyses (SEM/EDS, FTIR, contact angle), and in vitro cytotoxicity and osteogenic differentiation tests were performed to characterize the performance of the coatings and substrates. The results indicated that both methods enable the deposition of adherent bioactive layers, although only powder bed annealing demonstrated increased hydrophilicity and maintenance of adequate mechanical properties. The method also stands out for its uniformity and greater coating thickness, with compressed air jetting standing out negatively due to its difficulty of execution and deleterious thermal damage to the sample geometry. Biological tests confirmed the absence of cytotoxicity and the stimulation of osteogenic differentiation, demonstrating the clinical potential of the techniques. It can be concluded that the proposed processes represent low-cost alternatives compatible with resorbable polymers, with potential for integration into production processes for customized orthopedic implants. It is recommended to continue studies focusing on parametric optimization, durability assessment under simulated conditions and in vivo validation.