Sol-gel coatings made using methyl-modified alkoxysilanes: The balance between protection and bioactivation

abstract

The reported osteogenic properties of the hybrid silica sol-gel materials make these compositions perfect candidates for bone tissue engineering applications. The aim of this study was the synthesis and characterisation of hybrid silica coatings, obtained using mixtures of tetraethyl orthosilicate (TEOS) and three different methyl-modified alkoxysilanes: trimethoxymethylsilane (MTMS), dimethyldiethoxysilane (DMDES) or polydimethylsiloxane (PDMS). A comparison of the properties of these materials can reveal the best candidate for the coatings on metallic prostheses. After optimising the synthesis parameters, the developed coatings were characterised using Fourier transform infrared spectrometry (FT-IR), H-1 and Si-29 solid-state nuclear magnetic resonance (H-1-NMR and Si-29-MNR), cross-cut tests, scanning electron microscopy (SEM), contact angle measurements, optical profilometry, hydrolytic degradation tests and electrochemical corrosion analysis. Homogeneous and well-adhering coatings were obtained using the three methyl-modified reagents. However, different degrees of protection against corrosion, different hydrophilicity and varying degradation kinetics were observed for different precursors. The MTMS-based coating showed the highest hydrophilicity and degradation kinetics; these properties can be associated with increased bioactivity (Si release). In contrast, the PDMS and DMDES-based coatings showed augmented resistance to corrosion and lower permeability to water and, consequently, improved protection of metallic surfaces. From the physicochemical point of view, all these materials displayed interesting characteristics, relevant for coatings to be used in biomedical applications.

keywords

HYBRID MATERIALS; FT-IR; IMPLANTS; TITANIUM; HYDROLYSIS; WETTABILITY; DEGRADATION; SILOXANE

subject category

Chemistry; Materials Science

authors

Romero-Gavilan, F; Carlos-Almeida, J; Cerqueira, A; Gurruchaga, M; Goni, I; Miranda-Salvado, IM; Fernandes, MHV; Suay, J

Groups

G3 - Electrochemical Materials, Interfaces and Coatings

Projects

CICECO - Aveiro Institute of Materials (UID/CTM/50011/2019)

Rede Nacional de Ressonância Magnética Nuclear (PTNMR)

acknowledgements

This work was supported by MINECO [MAT2017-86043-R], Universitat Jaume I under [UJI-B2017-37, Predoc/2014/25 and the researcher mobility grant E-2016-31], the University of the Basque Country under [UFI11/56] and Basque Government under [IT611-13]. In addition, this work was developed within the scope of the project CICECO-Aveiro Institute of Materials, FCT Ref. [UID/CTM/50011/2019], financed by national funds through the FCT/MCTES. The NMR spectrometers used in this work are part of the Portuguese National NMR Network (PTNMR), partially supported by Infrastructure Project N degrees 022161 (co-financed by FEDER through COMPETE 2020, POCI and PORL and FCT through PIDDAC). Authors would like to thank Raquel Oliver and Jose Ortega for their valuable technical assistance.