Strong Adhesion of Graphene Oxide Coating on Polymer Separation Membranes

Abstract

Graphene oxide (GO) has been demonstrated as the most promising candidate for surface modification of polymer separation membranes for durable filtration applications. However, the adhesion between GO coating and polymer substrate, as the most essential issue for reliable applications, has been little explored. Herein, we developed a facile high-pressure assisted deposition method to physically anchor GO sheets on microfiltration (MF) and reverse osmosis (RO) membranes, and established a tape test procedure for assessing the adhesion of GO coating to polymer substrates based on the ASTM D3359. Through regulating the GO sources and coating process, we demonstrated that the adhesion depends sensitively on the GO flake size and deposition pressure, whereas the adhesion level dramatically improved from 0B to 5B, with decrease in the lateral size of GO and increase in the coating deposition pressure. The strong GO coatings showed evidently higher water flux than that of weak counterparts. The underlying mechanism was further analyzed and verified. Nanosize of GO and high deposition pressure favor the formation of the conformal morphologies of GO coatings on both MF and RO membranes, which allow strong interfacial van der Waals interaction because of the large contact areas and result in the strong GO coatings on membranes. These results potentially open up a versatile pathway to develop the strong graphene-based coatings on separation membranes.

Molecular Bridges Stabilize Graphene Oxide Membranes in Water

“…[12,14] Intrinsically,f lexible GO nanosheets with au nique 2D structure tend to attach only to the surface of the substrate, and the internal elastic strain energy from bending further induces GO laminate peeling and detachment. [15] Moreover,it is difficult to create ah ighly adhesive platform for ap orous substrate with am icrometer-scale rough and inert surface using conventional surface modifications with short-chain agents. [16] Herein, we propose am ethod for creating an interfacial long-chain molecular bridge,which provides large contact areas with the porous substrate layer and binds chemically with the GO laminate layer.…”

Molecular Bridges Stabilize Graphene Oxide Membranes in Water

“…Although the interlaminar short‐chain molecular bridge efficiently averts the undesired redispersion of GO nanosheets in water, a GO laminate could easily peel away from the substrate during the separation process because of inadequate adhesion . Intrinsically, flexible GO nanosheets with a unique 2D structure tend to attach only to the surface of the substrate, and the internal elastic strain energy from bending further induces GO laminate peeling and detachment . Moreover, it is difficult to create a highly adhesive platform for a porous substrate with a micrometer‐scale rough and inert surface using conventional surface modifications with short‐chain agents .…”

“…We summarized representative results in the recent literature involving stability evaluations of two‐dimensional material membranes, including membranes based on GO, covalent organic frameworks (COF), g‐C 3 N 4 , and MXene (Supporting Information, Table S1), and illustrated their long‐term operation in water‐based separations, such as desalination, nanofiltration, and pervaporation (Figure e). Promisingly, the superior stability of our GO‐PDA/O=CS/ceramic membrane offers a greater competitive advantage over other counterparts—especially where long‐term operation is required that demand much more stringent requirements for membrane stability.…”

Graphene-based composite membranes for nanofiltration: performances and future perspectives

“…1) [23]. The same principle was used for the synthesis of other membranation systems for NF [24][25][26]. Another innovative method is to obtain graphene films, dressed in the polymer.…”