Preparation And Properties Of Modified Graphene-carbon Nanotube-polyhydroxybutyrate Composite Nanofiber Membranes

Electrospinning technique,by which electrostatic forces are employed to control the formation of fibers,is an attractive method that can readily produce fibers with diameters ranging from scores of nanometers to several micrometers from both natural and synthetic polymers.Electrospun regenerated polyhydroxybutyrate fiber are characterized by small diameter and high specific surface area.Besides,with good biocompatibility and degradability,electrospun regenerated polyhydroxybutyrate fiber mat can be used as ideal candidates for tissue-engincered scaffolds,wound dressings and drug delivery systems.However,the mechainical properties of the electrospun regenerated PHB fiber mat is poor.The brittleness is very big and toughness is poor.Thus,it is prone to embrittle in actual use,which limits its potential application in many aspects.The mechanical properties of polyhydroxybutyrate can be improved by adding graphene and carbon nanotubes with excellent mechanical properties as reinforcements.The main work of this thesis includes the following three parts:(1)The octadecylamine modified graphene was prepared by the nucleophilic addition reaction between octadecylaminc and the epoxy groups on graphene oxide to improve the dispersibility of graphene oxide in choroform.Using chloroform/DMF as solvent,the modified graphene was dispersed in the polyhydroxybutyrate spinning solution,and use electrospinning technology to prepare a modified graphene/polyhydroxybutyrate composite nanofiber membrane.The effect's of modified graphene on the chemical structure,crystal structure,thermal stability,contact angle and mechanical properties of modified graphene/polyliydroxybutyrate composite nanofibrous membranes were investigated.(2)Using EDC/NHS as a condensing agent,the octadecylamine modified carbon nanotubes were prepared by the amidation reaction between octadecylamine and carboxylated multi-walled carbon nanotubes to improve the dispersion stability of the carboxylated multi-walled carbon nanotubes in chloroform.Using chloroform/DMF as solvent,the modified carbon nanotubes was dispersed in the polyhydroxybutyrate spinning solution,and use electrospinning technology to prepare a modified graphene/polyhydroxybutyrate composite nanofiber membrane.The effects of modified graphene on the chemical structure,crystal structure,thermal stability,contact angle and mechanical properties of modified graphene/polyhydroxybutyrate composite nanofibrous membranes were investigated.(3)Using chloroform/DMF as solvent,the modified graphene and modified carbon nanotubes were simultaneously dispersed in the polyhydroxybutyrate spinning solution for electrospinning to prepare modified graphene/modified carbon nanotube/polyhydroxybutyrate composite nanofibers membrane.The effects of modified graphene pand modified carbon nanotubes on the chemical structure,crystal structure,thermal stability,contact angle and mechanical properties of modified graphene/modified carbon nanotubes/polyhydroxybutyrate composite nanofibrous membranes were investigated.