Active Porous Materials Based on Organic Hybrids of Carbon Nanostructures

Over the last years, nanotechnologies have been implemented in almost all branches of human activities, including biomedicine and wastewater treatment. In these fields, characteristics such as high surface area, surface reactivity and variable porosity could be very attractive for the development of innovative materials. Carbon nanostructures (CNS) exhibit distinctive and advantageous properties; however, their propensity to aggregate severely restrict their practical applications. The central focus of this thesis is the design of chemical modification of CNS, avoiding harsh treatments damaging the basal plane, to implement their use in tissue engineering and environmental purification. The aim is to understand the phenomena occurring at the surface of materials and to take advantage of chemistry skills to modulate properties such as surface availability and interactions with the surroundings. Specifically, interactions of the surface with pollutant molecules are exploited in the environmental field applications, or those with cells and tissues in the biomedical domain. Furthermore, surface modification enables the incorporation and potential interactions of CNS with polymeric matrices, which can act as a support for the nanometric material. The combination of these nanostructures with highly porous matrices provides new multifunctional behaviors to conventional materials, giving rise to composites of high interest. The research activity is divided into three chapters: Chapter 1 provides a comprehensive overview of CNS. The introduction describes CNS structures, their properties, applications, synthesis, as well as possible methods for surface modification and their inclusion in different polymer matrices. The chapter reports on the synthesis of CNS derivatives synthetized during the thesis work and their characterization for the assessment of nanostructure conformity and the presence of the chosen functional groups. In addition, this chapter provides a comparison of the potential for the scale-up of functionalization strategies through batch or continuous-flow hydrothermal processes. Chapter 2 focuses on the use of CNS derivatives for water treatment applications. The chapter delineates the environmental concerns associated with the presence of emerging organic contaminants in surface, ground, and waste waters. An exhaustive description of water treatment techniques, with a particular emphasis on adsorption processes, is provided. Additionally, the chapter discusses the existing literature on nanostructures for the removal of water pollutants. The chapter further reports the studies conducted on CNS derivatives for the adsorption of organic pollutants, including dyes, drugs and PFAS. A preliminary study of a geopolymer porous matrix for flow adsorption systems is also reported, with the future purpose of combining it with functionalized CNS. Chapter 3 explores the use of CNS derivatives for biomedical applications, beginning with an overview of regenerative medicine with a focus on tissue engineering techniques. The prerequisites of scaffolds for cell growth and the factors influencing cell behavior and differentiation are then outlined. The present chapter emphasizes the role of the CNS as structural, mechanical and electrical stimuli in combination with different polymer matrices. The results about functionalized carbon nanotubes as fillers in composite hydrogels and as coatings on PDMS substrates are reported and discussed. Furthermore, studies on the modification of the surface topography of materials with aligned micropatterns for the growth and differentiation of cells are presented. The materials obtained are tested for neuronal or muscle tissue engineering.