관능성 그라펜의 고분자 복합재료에 관한 연구 : Functionalized Graphenes and Their Use in Fabrication of High Performance Polymer Composites
다오 충 둥
정 한 모
- 원문 URL
Graphene, a single-atom-thick sheet of hexagonally arrayed sp2-bonded carbon atoms, has attracted a great deal of attention because of its extraordinary electronic, electrochemical, thermal, and mechanical properties, large surface area, and high aspect ratio, providing it with potential for a variety of applications such as in electronic and energy devices, catalysis, sensors, biomedicines, and composite materials. Extensive studies have been performed using graphene as an effective nanofiller for the fabrication of advanced polymer composites with substantially improved properties, including mechanical, electrical, thermal, and gas barrier properties. In order to maximize the contribution of graphene to the performance of the composite, various preparation methods and techniques have been applied in the fabrication of polymer/graphene composites, including not only general melt or solution blending, or in-situ polymerization with the graphene dispersed in monomers, but also the modification of graphene and/or polymers to enhance the dispersion and the interfacial interaction between graphene and polymer matrices. In addition, a well-designed composite structure can maximize the performance of the composite for a tailor-made application. The preparation of graphene from graphite oxide by thermal reduction accompanied exfoliation has been known as a facile, economical and eco-friendly approach to produce bulk quantities of graphene without the use of solvents or hazardous chemicals. Additional modifications or functionalizations of this graphene can pave the way toward various promising applications. In this Ph. D. dissertation, the thermally reduced graphene was functionalized by various methods including non-covalent and covalent modifications, and then used for the fabrication of various high performance polymer composites. The dissertation comprises of five chapters. Chapter 1 presents the method of coating graphene with a thin alumina layer to form hybrid nanosheets, which exhibited excellent performance not only as an insulative reinforcing filler of acrylic rubber but also as a filler for enhancing thermal conductivity of the rubber composite prepared by a melt blending approach. Chapter 2 reports the covalent modification of graphene by ethanolamine and then n-butyl bromide to form a graphene decorated with cationic moieties, which can be effectively used as a novel water-dispersible filler for the preparation of a high modulus poly(vinyl alcohol)/graphene composite using a solution blending method. Chapter 3 reports the modification of graphene by oxidation with hydrogen peroxide to introduce additional oxygen functional groups to the graphene surface, which enhanced compatibility and dispersion of graphene in a polycaprolactone (PCL) matrix for the preparation of a high performance PCL/graphene composite using an in-situ polymerization method. Chapter 4 reports the covalent modification of graphene by potassium 2-aminoethanesulfonate to form a graphene decorated with anionic moieties, which can be effectively utilized as a Pickering stabilizer for suspension polymerization of poly(methyl methacrylate)/graphene core-shell composite microsphere exhibiting excellent thermal and electrical properties. Chapter 5 presents the functionalization of graphene with polycaprolactone brushes on the surface by polymerization of caprolactone from functional groups on graphene, and the utilization of this functionalized graphene for fabrication of a super-tough composite paper which showed potential use as a high-capacity anode for lithium ion batteries. All the works in the dissertation were carried out in a thorough and systematic way with hope that they can significantly contribute to the development of the field.