Functionalization of graphene based on the coupling of acylium ions under conditions similar to Friedel-Crafts acylation is reported. The reaction is applied to the functionalization of graphene with low molecular weight polypropylene, and the resulting material when incorporated as a filler significantly enhances the electrical, mechanical and thermal performance of a commodity polymer like polypropylene. ; The authors thank the Spanish Government (MINECO) for nancial support (Projects: MAT2013-47898-C2-2-R and MAT2014-54231-C4-4P), a Ramon y Cajal Research Fellowship (H. J. S.) and a FPI studentships (S. Q. D). Also Mr David G´omez and Ms Isabel Muñooz (Characterization Service of the Institute of Polymer Science & Technology) are gratefully acknowledged for the SEM and Raman measurements, respectively ; Peer Reviewed
9 pags., 5 figs., 4 tabs. ; Nanocomposites of polypropylene were prepared with different loadings of both commercially-available graphene and graphene that had been modified with low molecular weight polypropylene brushes. The dependence of the thermal stability, electrical conductivity and mechanical properties of the composites on the type and loading of graphene have been investigated. The mechanical properties were studied using several techniques, including nanoindentation, four-point bending coupled to Raman spectroscopy and tensile testing. Significant differences on the mechanical performance, due to the influence of graphene content and modification, have been observed; i.e. the Young's modulus takes values up to 30% higher for nanocomposites with modified graphene, compared to those with pristine graphene. Different trends on the variation of mechanical properties have been encountered at the local and macro scales and a discussion of the respective results from the different techniques is offered. Finally, the behavioral changes on the electrical conductivity are also discussed. ; Financial support by MINECO, Spain (Grants MAT2013-47898- C2-1-R and MAT2013-47898-C2-2-R) is gratefully acknowledged. S.Q.-D. and P.E.-J. acknowledge a FPI Fellowship. D.G.P, I.A.K and R.J.Y acknowledge funding from the European Union Seventh Framework Programme under grant agreement no 604391, Graphene Flagship. ; Peer Reviewed
We have deposited 4-aminophenol on Pt(111) surfaces in ultra-high vacuum and studied the strength of its adsorption through a combination of STM, LEED, XPS and ab initio calculations. Although an ordered (2√3 × 2√3)R30° phase appears, we have observed that molecule–substrate interaction dominates the adsorption geometry and properties of the system. At RT the high catalytic activity of Pt induces aminophenol to lose the H atom from the hydroxyl group, and a proportion of the molecules lose the complete hydroxyl group. After annealing above 420 K, all deposited aminophenol molecules have lost the OH moiety and some hydrogen atoms from the amino groups. At this temperature, short single-molecule oligomer chains can be observed. These chains are the product of a new reaction that proceeds via the coupling of radical species that is favored by surface diffusion. ; We acknowledge funding from the Spanish MINECO (Grants MAT2014-54231-C4-1-P, MAT2014-54231-C4-4-P and MAT2013-47898-C2-2-R), the EU via the ERC-Synergy Program (Grant ERC-2013-SYG-610256 NANOCOSMOS), and computing resources from CTI-CSIC. MKS and GOI acknowledge financial support from FCT (Grant No. PTDC/CTM-NAN/121108/2010 and SFRH/BPD/90562/2012), Ministry of Science and Technology, Portugal. HJS would like to acknowledge the MICINN for a "Ramón y Cajal" Senior Research Fellowship, Spain. JIM acknowledges funding from both the CSIC-JAE-Doc Fellowship Program (co-funded by the European Social Fund). The research leading to these results has received funding from the European Union Seventh Framework Programme under Grant agreement No. 604391 Graphene Flagship. ; Peer reviewed
