title: Investigation on the use of graphene oxide as novel surfactant to stabilize weakly charged graphene nanoplatelets.
abstract: This paper presents a unique synergistic behavior between a graphene oxide (GO) and graphene nanoplatelet (GnP) composite in an aqueous medium. The results showed that GO stabilized GnP colloid near its isoelectric point and prevented rapid agglomeration and sedimentation. It was considered that a rarely encountered charge-dependent electrostatic interaction between the highly charged GO and weakly charged GnP particles kept GnP suspended at its rapid coagulation and phase separation pH. Sedimentation and transmission electron microscope (TEM) micrograph images revealed the evidence of highly stable colloidal mixtures while zeta potential measurement provided semi-quantitative explanation on the mechanism of stabilization. GnP suspension was confirmed via UV-vis spectral data while contact angle measurement elucidated the close resemblance to an aqueous solution indicating the ability of GO to mediate the flocculation prone GnP colloids. About a tenfold increase in viscosity was recorded at a low shear rate in comparison to an individual GO solution due to a strong interaction manifested between participating colloids. An optimum level of mixing ratio between the two constituents was also obtained. These new findings related to an interaction between charge-based graphitic carbon materials would open new avenues for further exploration on the enhancement of both GO and GnP functionalities particularly in mechanical and electrical domains.
authors.affiliation: Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia.
authors.forename: Salim Newaz
authors.initials: SN
authors.lastname: Kazi
authors.affiliation: Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Badarudin
authors.affiliation: Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia.
authors.forename: Mohd Nashrul Mohd
authors.initials: MN
authors.lastname: Zubir
authors.affiliation: Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia.
authors.forename: Huang Nay
authors.initials: HN
authors.lastname: Ming
authors.affiliation: Department of Chemistry, Faculty of Science, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia.
authors.forename: Misni
authors.initials: M
authors.lastname: Misran
authors.affiliation: Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia.
authors.forename: Emad
authors.initials: E
authors.lastname: Sadeghinezhad
authors.affiliation: Department of Mechanical Engineering and Advanced Material Research Centre, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Mehrali
authors.affiliation: Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia.
authors.forename: Nur Ily
authors.initials: NI
authors.lastname: Syuhada
keywords: Electrostatic stabilization; Graphene nanoplatelets; Graphene oxide; Hybrid complexes; Isoelectric point; Weakly charged colloids