ANNUAL REPORT 2011 - Instituto de Estructura de la Materia

GISAXSAFMX-Ray beamLIPSS polymer filmExperimental set-up to perform GrazingIincidenceSmall-Angle X-ray scattering (GISAXS) with synchrotronradiation. The X-ray beam reaches the polymer surface, nanostructured by means of LIPSS, at an angle of totalreflection. The evanescent wave propagating along the sample gives rise to diffraction features which are collectedon a screen. From the analysis of the structure in real space (AFM) and in reciprocal space (GISAXS) a verycomplete picture of the nanostructure can be obtained.Nanoimprint Lithography.We have performed studies on nanoimprint lithography (NIL) in polymers, incollaboration with the group of Professor Francesc Pérez-Murano for Centro Nacional de Microelectrónica (CNM-CSIC, Barcelona). On one hand, the process for stamp preparation was optimized. On the other hand, a study of theunderlying physics of the nanoimprint process in polymeric materials is being carried out. The obtained structuresare being analyzed by atomic force microscopy and X-ray spectroscopyFunctional Polymer Materials through addition of nanoparticles. Preparation of Composite Materials basedon Carbon Nanofibers, Carbon Nanotubes and Graphene.Continuing our cooperation with the company GrupoAntolín Ingeniería, S.A. we have developed nanocomposites based on polyamide 6,6 (PA66) and carbon nanofibers(CNFs) following a new procedure. It consists essentially of the physical mixing, by a vortex mixer, of the polymermatrix, in the form of powder as prepared by cryogenic grinding, and the corresponding amount of CNFs. Thematerials present good electrical conductivity at lower percolation thresholds than those corresponding to systemsprepared by melt compounding, which is the method commonly used in the industry. Part of this study has beenpatented. In addition, we have prepared composites based on polyvinylidene fluoride (PVDF) and differentcarbonaceous compounds such as single wall carbon nanotubes (SWCNT), carbon nanofibers provided by GrupoAntolín Ingeniería, S.A., expanded graphite (EG) and graphite. In this case, dissolution has been the synthesisprocedure. First, we are studying electrical, thermal and mechanical properties of these compounds and, secondly wewill characterize these materials from a structural and morphological point of view, in order to establish thecorresponding relationship between structure and properties. Thus, different compounds have been prepared, in awide range of concentrations, and electrical and thermal studies have been conducted. Interesting differences havebeen observed mainly as far as electrical properties are concerned.Within the same context, nanocomposites of Poly (trimethylene terephthalate)(PTT) containing functionalizedmulti-walled carbon nanotubes (MWCNT) have been synthesized by in situ polymerization method. In comparisonwith neat PTT, the MWCNTs reinforced nanocomposites possess higher tensile strength and Young's modulus atlow MWCNTs loading. In addition, all nanocomposites show reduction of brittleness as compared to the neat PTT.The electrical percolation threshold was found between 0.3 and 0.4 wt% loading of MWCNTs.During 2011 and in collaboration with the groups of Prof. Z. Roslaniec of the West Pomeranian University ofTechnology (Szczecin, Poland) and with the group of Dr. M.A. López-Manchado (ICTP-CSIC, Madrid), we havestarted preparation of Polymer/graphene (expanded graphite) nanocomposities exploring different polymer matrixes.Initial studies indicate achievements of electrical conductivity at very low nanoadditive concentrations. Exploitationof these nanocomposites in order to obtain conducting and transparent materials is going on.Nanocomposites based on thermoplastic polymers reversibly crosslinked with clay.Following the research lineinitiated some years ago, we have prepared nanocomposites of clay with some thermoplastic polymers reversiblycrosslinked by reactive extrusion: isotactic polypropylene iPP, polyethylene, PE and isotactic polybutene-1, iPB-1 inone step. Some modifications introduced in the preparation method allowed us to improve the properties of the final75