Modificação superficial de filmes finos poliméricos por feixe de íons e tratamentos térmicos

• Autor(a) principal: Esteves, Christian Roberto Becker
• Data de Publicação: 2018
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da PUC_RS
• Texto Completo: http://tede2.pucrs.br/tede2/handle/tede/8449
• topic: Filmes Finos Poliméricos; Estabilidade Térmica; Irradiação; Polymer Thin Films; Thermal Stability; Irradiation; ENGENHARIAS

In this work, the surface modification by ion irradiation and heat treatment of PMMA and PVC thin films with different thicknesses (between 2.5 and 290 nm) deposited on Si wafers was investigated. Three different conditions were tested: a) heat treatment in vacuum chamber with temperatures between 80 °C and 224 °C, up to 72 h ; b) high energy ions irradiation (2 MeV H+, 17 MeV Au+7 and 2.2 GeV Bi+eq) at temperatures that varied from -196 °C to 150 °C and c) ion irradiation associated with subsequent annealing at temperatures between 80 °C and 224 °C in times up to 72 h. Heat treatment by itself, in most cases, did not show any significant changes in the roughness and porosity of the films, save for T = 100 °C and long treatment times (72 h). PMMA and PVC films irradiated with H+ underwent a smoothing process after high irradiation fluencies, probably because the chain motility was increased by irradiation-induced scission. However, irradiations with Au+7 and Bi+eq strongly increased the roughness of the films due to the high erosion caused by the ions. The irradiation with Au+7 ions associated with temperatures above room temperature contributed to the increase of the roughness, forming new surface defects patterns. When the ion irradiation is combined with the temperature, a modification in the pattern of the structures on the film occurs, with higher occurrence of waves with low spatial frequency. However, the effects of irradiation combined with heat treatment showed roughness increase for long exposure times, probably as a result of the polymer mobility increase with increasing temperature and time. Complementary contact angle measurements indicated higher wettability for H+ irradiations, reaching a strong decrease for Bi+eq ions, this is due to the strong chemical modifications that are generated in the structure of the film by both ions. Finally, an analysis of the modulus of elasticity was performed by nanoindentation and AFM techniques, in order to compare the data obtained by both techniques. The measurements obtained by the nanoindenter data showed great influence of the substrate, with values higher than those described in the literature, contrary to the AFM, in which similar values to the literature were found. The PVC films presented an increase in the elastic modulus with the increase of the fluence, but for the PMMA films the opposite effect was observed, presenting a decrease in the elastic modulus.