Surface-tunable, electrically conductive and inexpensive graphene platelets and their hydrophilic polymer nanocomposites. (28th September 2020)

• Record Type: Journal Article
• Authors: Wang, Ruoyu; Aakyiir, Mathias; Qiu, Aidong; Oh, Jeong-A.; Adu, Philip; Meng, Qingshi; Ma, Jun
• Is Part Of: Polymer. Volume 205(2020)
• Publication Date: 2020-09-28
• Subjects: Graphene nanoplatelets (GnPs) -- Microwave expansion -- Hydrophilicity; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2020.122851
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: A cost-effective method is essential for the applications of graphene platelets (GnPs) in polymer processing industry. Herein, a simple microwave expansion method was introduced to prepare graphene platelets (GnPs) of 11.7 ± 4.3 nm in thickness. By controlling the concentration of nitric acid, the surface of GnPs was tuned to be hydrophilic without causing severe damage to their structural integrity; the modified GnPs had thickness of 4.6 ± 2.1 nm, Raman I D /I G ratio of 0.09 and electrical conductivity of 570 S cm −1 . The platelets' high crystallinity before and after the surface modification was proved by TEM and SAED analysis. A percolation threshold of electrical conductivity was found to be 0.89 vol% for poly (vinyl alcohol)/modified GnP nanocomposites. The platelets at 0.5 vol% improved tensile strength by 91.1% and Young's modulus by 66.7% due to relatively uniform dispersion and strong interfacial interactions with the matrix. Graphical abstract: Image 1 Highlights: This is the first time that a microwave oven was employed to produce graphene nanoplatelets (GnPs). A microwave oven is more convenient to operate with lower costs than a furnace, which makes this method cost-effective. The modification method not only tuned the GnPs' surface to be hydrophilic but also maintained their high structural integrity and properties. Low-concentration nitric acid commonly used for CNTs' surface modification proved effective for GnPs. The PVA/modified GnP composites showed far higher electrical and mechanical performance in comparison with those reported. No report was made to use GnPs to reinforce PVA.