טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentGuy Mechrez
SubjectHighly-Tunable Polymer/CNTs Nanostructures: A New
Approach for Controlled Structure and Properties
DepartmentDepartment of Chemical Engineering
Supervisors Professor Emeritus Narkis Moshe
Professor Segal Ester H.
Full Thesis textFull thesis text - English Version


Abstract

CNTs porous sheet networks (PSNs) have become an important topic in the research area of CNTs. A nanotubes network is a macroscopic porous structure of entangled CNTs. The preparation methods of CNTs networks involve dispersion of CNTs in a given solvent, and filtration under positive or negative pressure. The formed bed is a uniform porous sheet of CNTs network. In the present research, PSNs of enhanced elongation values containing DBSA are developed and studied. The strain at failure of these PSNs is in the range of 8-12%, significantly higher than the previous reports.

An immense research effort has been directed toward the development of Polymer/CNTs systems and nanocomposites. This research presents a new fabrication method for tailoring polymer/CNTs nanostructures with controlled architecture and composition. The CNTs are finely dispersed in a polymeric latex i.e. polyacrylate, via ultrasonication, followed by a microfiltration process. The latter step allows preserving the homogeneous dispersion structure in the resulting solid nanocomposite. The combination of microfiltration and a proper choice of the polymer latex, particle size, and composition allows the design of complex nanostructures with tunable properties e.g., porosity and mechanical properties. An important attribute of this methodology is the ability to tailor any desired composition of polymer-CNTs systems. Thus, for the first time a given polymer/CNTs system is studied over the entire CNTs composition. The polyacrylate in these systems exhibits a structural transition from a continuous matrix (nanocomposite) to segregated domains dispersed within a porous CNTs network. The resulting polyacrylate/CNTs layers exhibit a percolation threshold as low as 0.04 wt%. Additionally, these nanomaterials show low total reflectance values throughout the visible, NIR and SWIR spectrum at a CNTs content as low as 1 wt%, demonstrating their potential applicability for optical devices.

Organophosphate (OPs) are among the most toxic substances synthesized to date. Biotechnological methods based on the use of organophosphate hydrolase (OPH) for detoxification of OPs have drawn significant attention. This work presents a new ‘one-pot’ methodology for a rapid and straightforward fabrication of enzymatically-active CNT membrane for OPs bioremediation. Carboxylated CNTs are ultrasonically dispersed in an aqueous surfactant solution followed by a microfiltration process, to generate a Buckypaper. The OPH conjugation to the CNTs is carried out during the microfiltration process. To study the potential of this platform for OPs bioremediation, an aqueous solution of a model OP is filtered by the resulting membranes. A significant decrease of OP concentration is obtained.