Preparation and Properties of Graphene/Polyurethane Conductive Polymer Composite Films

Graphene shows many exceptional properties, such as electrical, thermal, optical, and mechanical properties. When it was used as nanofiller in the preparation of polymer nanocomposites, the properties of the polymer matrix could not be fully exhibited due to easy agglomeration of graphene and bad compatibility between polymer matrix and graphene.[1,2] Polyurethane (PU) is a material characterized by excellent flexibility, high resilience, and durability. PU has been applied in a wide range of industrial applications including coatings, adhesives, foams, and elastomers.

In our study, the surfactant was first introduced to improve the dispersion of graphene in distilled water. The PU copolymer was synthesized with 2, 4-toluene diisocyanate, polyethylene glycol (PEG400) and    2-hydroxyethyl methacrylate. The triethylamine and ethylene diamine reacted with the copolymer as the neutralizing agent and chain extander, respectively. The graphene/PU polymer composite film was cast on glass substrate and cured under UV irradiation. Dispersion of graphene in the polymer matrix strongly depended on the type of surfactant agent, which was confirmed by scanning electron microscopy measurements and thermogravimetric analysis. Decomposition temperatures and residues of the samples increased with the increasing of graphene content. The conductivity of the films was evidently improved due to the introduction of graphene, which was investigated by using a four probe tester. The composite films were bright and transparent. The graphene/PU polymer composite film showed satisfactory conductivity, transparency and thermal resistance properties because the graphene was well dispersed in the polymer matrix. These polymer composite thin films are good candidates that can be applied in various electronic devices such as counter electrode in solar cells, anode materials in rechargeable batteries and light emitting diodes, and so on.

Reference:

[1] H. B. Zhang, W. G. Zheng, Q. Yan, Z. G. Jiang, Z. Z. Yu, Carbon, 50, 5117 (2012).

[2] J. H. Du, H. M. Cheng, Macromol. Chem. Phys. 213, 1060 (2012).