Pyrene-functionalized poly(methacrylic acid) acts as an efficient stabilizer for graphene nanoplatelets and facilitates their use in waterborne latex formulations.

ABSTRACT

HYPOTHESIS: Pyrene derivatives are effective motifs when designing graphene-philic surfactants, enabling the use of hydrophobic graphene-based nanomaterials in waterborne formulations. Hence, novel pyrene end-functionalized polymeric stabilizers show promise for stabilizing aqueous graphene nanomaterial dispersions, and offer benefits over traditional small molecule surfactants. EXPERIMENTS Pyrene end-functionalized poly(methacrylic acid) (Py-PMAAn, where n = 68 to 128) was synthesized by reversible addition-fragmentation chain-transfer (RAFT) polymerization of MAA using a pyrene-containing RAFT chain-transfer agent. These polymers were evaluated as aqueous graphene nanoplatelet (GNP) stabilizers. Subsequently, polymer-stabilized GNPs were formulated into film-forming polymer latex dispersions and the properties of the resulting GNP-containing films measured. FINDINGS: Py-PMAAn homopolymers with well-defined molecular weights were prepared via RAFT solution polymerization. They served as efficient stabilizers for aqueous GNP dispersions and performed better than a traditional small molecule surfactant and non-functionalized PMAA, especially at higher pH and with higher molecular weight polymers. The use of Py-PMAAn allowed GNPs to be readily formulated into waterborne latex coatings. When compared to controls, the resulting films were significantly reinforced due to the improved homogeneity of dried nanocomposite films and chain entanglement between the polymer matrix and stabilizers. Thus, the ability to readily incorporate GNPs into aqueous formulations and enhance GNP/polymer matrix interfaces was demonstrated for these novel amphiphilic stabilizers.