Functionalization of graphene from electrochemical exfoliation and fluorographene reduction for use in polyurethane composite materials

Abstract

Composite materials are employed in a wide variety of markets, including aerospace, architecture, automotive, energy, infrastructure, marine, military, and sports and recreation, due to the significantly different and advanced physical or chemical properties, compared with the individual components used for making the composites. Based on the desire products, focusing on strength and conductivity, functional graphene is used to combine with polyurethane (PUR) to make a new composite material for industries. Two types of functional graphene were discussed and studied in this thesis, which are rendered from exfoliated graphene (EG) and fluorographene (FG) methods. In EG, the functional graphene was produced in only one step by using chemical exfoliation with diazonium salts in the electrolyte, which was employed as the functional groups on graphene sheets. However, functional graphene from FG was prepared within two steps, consisting of cyanidation fluorographene and amine conversion. The yield of functionalization of FG is much higher than the functionalization of EG.

To utilize the graphene properties in the composites, growing polymer brushes from functional groups on graphene is suggested and carried out for the EG; the process called as polymerization. The composite material samples with graphene presence is stiffer than the pure PUR sample, meaning the efficiency of graphene. In particular, the functional graphene presents the highest quality in the composite, while the composite from polymerized graphene is a bit stronger than the one mixed only with graphene. Besides, the concentration of graphene content in composite could influence the strength of the composite, in which the higher the concentration of the graphene content is, the stiffer the composite becomes.