Control of the structure and properties of SEBS nanocomposites via chemical modification of graphene with polymer brushes

Incorporation of small quantities of graphene modified with polystyrene brushes into poly (styrene-b-ethylene-co-butylene-b-styrene) (SEBS) produces elastomeric conductive nanocomposites with enhanced electromechanical behaviour. Compared to graphene modified with polyethylene rubbery brushes, polystyrene-modified graphene distorts the hexagonal packing of cylinders in SEBS to a lesser extent due to the selective interactions with the rigid polystyrene blocks. At the same time, the type of filler has an apparent impact in the nano-, macro- and electro-mechanical properties of the nanocomposites. Consistently, AFM nanoindentation shows a narrower distribution of modulus values for the polystyrene modification. Moreover, tensile testing reveals that only the nanocomposites with styrene-affine fillers show elongation at break comparable to SEBS. Most importantly, a stable electromechanical behaviour is only found for the polystyrene modification, which is attributed to the selective interaction of the brushes on graphene with the polystyrene blocks of the matrix. The work offers a comprehensive understanding of the interplay between the nature of the polymer brush grafted to graphene, the nanostructure of the nanocomposites and their final properties.The SAXS experiments were performed at BL11 beamline at ALBA Synchrotron with the collaboration of ALBA staff.Funding Fig. 11. Electromechanical tests. Resistance change as a response to cyclic strain for 2gpsSEBS (a, c) and 2gpeSEBS (b, d). P. Enrique-Jimenez et al. European Polymer Journal 97 (2017) 1–13 11 sources Financial support from MINECO (Ministerio de Economía y Competitividad), Spain, for funding the research reported under grants MAT2013-47898-C2-1-R, MAT2013-47898-C2-2-R is gratefully acknowledged. PEJ and SQ also acknowledge the MINECO for a FPI Fellowship. PEJ additionally thanks the MINECO for a grant under the Predoctoral Mobility Program (EEBB-I-16-10848). This work was also supported by the European Research Council (ERC project ASMIDIAS, Grant no. 279202), the Deutsche Forschungsgemeinschaft (DFG grant no. INST 221/87-1 FUGG) and the University of Siegen.Peer Reviewe