Development of multifunctional PMMA-(TiO2, ZrO2 and CeO2) hybrids

Author(s)

Samarah Vargas Harb

• Document type: Doctoral Thesis
• Press: Araraquara. 2019-05-03.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Química. Araraquara
• Defense date: 2019-04-25
• Advisor: Peter Hammer

Abstract

Organic-inorganic hybrids consisting of poly(methyl methacrylate) (PMMA) covalently bonded to different inorganic phases (TiO2, ZrO2and CeO2) were synthesized by the sol-gel process in order to obtain multifunctional coatings that provide corrosion resistance to metallic substrates, besides presenting properties as thermal stability, biocompatibility and self-healing. For the development of the three studied hybrids several parametershave been varied, such as temperature and time of synthesis, deposition parameters, thermal treatment, amount of the thermal initiator benzoyl peroxide (BPO), and the proportion of precursors (methyl methacrylate (MMA) titanium isopropoxide, zirconium propoxide, cerium oxide and 2-hydroxyethyl methacrylate (HEMA)). PMMA-CeO2hybrids deposited on carbon steel by dip-coating have showed strong adhesion to the substrate, thermal stability close to 220 ºC, homogeneous and smooth surface, absence of cracks or porosity, excellent corrosion resistance, with impedance modulus up to 290GΩ cm2practically unchanged by approximately 6 months, and self-healing propertyas evidenced by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). PMMA-TiO2and PMMA-ZrO2hybrids deposited by dip-coating on carbon steel substrate have also showed low roughness, strong adhesion to the substrate, thermal stability close to 220 °C, and excellent anticorrosive protection. The PMMA-TiO2and PMMA-ZrO2coatingswith the best anticorrosiveperformance showed impedance modulus of50 GΩcm2and 10 GΩcm2, respectively,7 orders ofmagnitudehigher than uncoated carbon steel. PMMA-TiO2and PMMA-ZrO2hybrids with optimized synthesis conditions were modified with beta-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) and deposited on Ti6Al4V titanium alloy.These coatingshavepresented elevated corrosion resistance, with impedance modulusup to 500GΩcm2,and excellent biocompatibility, explained by the increase ofthe nanoscale roughness and by the higher surface free energy, which lead to a higheradsorption of proteins, and consequently proliferation of osteoblasts on the coatings surfaces. (AU)

• FAPESP's process: 15/09342-7 - Development of multifunctional PMMA- (TiO2, ZrO2 and CeO2)hybrids
• Grantee: Samarah Vargas Harb
• Support Opportunities: Scholarships in Brazil - Doctorate