Development of advanced elastomeric conductive nanocomposites by ...
Supporting information
Development of advanced elastomeric conductive nanocomposites by selective chemical affinity of modified graphene Horacio J. Salavagione, Susana Quiles-Díaz, Patricia Enrique-Jimenez, Gerardo Martínez, Fernando Ania, Araceli Flores, Marián A. Gómez-Fatou
Additional results on the characterization of SEBS and its nanocomposites with GPE. In order to further analyze the distribution of graphene we recorded TEM images of unstained samples (Figure S1). In this case the phase separation in the copolymer could not be observed but the images provide information on filler distribution. We focused on samples with graphene contents of 1.0 vol. % GPE or higher where graphene islands are uniformly distributed throughout the whole polymer matrix (Figure 1, main text). Both TEM images in Figure S1 confirm a good dispersion of the filler in the matrix. In the sample with higher filler content, 2.5 vol. %, regions of polymer matrix are intercalated between graphene sheets. These sheets are somewhat wrinkled and folded laminates (100-500 nm length), well distributed individually with a very small amount
of aggregates. These observations were also assessed by X-ray diffraction at wide angle carried out on SEBS and two nanocomposites of low and high graphene contents that showed no trace of a maximum associated to an interlayer spacing between graphene laminates.
Figure S1. TEM images of unstained samples of SEBS-GPE3 (A) and SEBS-GPE4 (B). As discussed in the main text, the phase separation in the block copolymer is clearly observed when one of them (the styrenic one) is stained with ruthenium tetroxide. However, under these conditions the contrast with graphene laminates becomes poor and it is hard to visualize their distribution in the matrix especially for low graphene content.
Figure S2 shows a high magnification TEM image of a stained
nanocomposite with high content of graphene (2.5 vol. % GPE), where some laminates can be clearly distinguished. Here, the filler appears as few-layer graphene composed of 4 to 8 laminates stacks and not dispersed as individual sheets. This fact does not put into question the good filler dispersion, but only reflects that a low contrast does not allow observing single laminates. From Figure S2 it can also be
suggested that the laminates are principally located in the ethylenic phase (bright area). However, the large filler size (from hundreds of nanometers to microns along the graphene plane) as compared to the distance among styrenic domains in SEBS (tens of nanometers) does not rule out a certain steric interaction of the laminates with such domains or interphases.
Figure S2. High magnification TEM image of SEBS-GPE4 stained with ruthenium tetroxide
Figure S3. Peak separation analysis of the Lorentz-corrected diffraction intensity profiles (black lines) for SEBS (left) and SEBS-GPE3 (right) of Figures 4A and 4D respectively. SAXS profiles were fitted to a number of Pearson VII curves (red lines) using the PeakFit® program (Systat Software Inc.).
Development of advanced elastomeric conductive nanocomposites by selective chemical affinity of modified graphene Horacio J. Salavagione, Susana Quiles-Díaz, Patricia Enrique-Jimenez, Gerardo Martínez, Fernando Ania, Araceli Flores, Marián A. Gómez-Fatou
Additional results on the characterization of SEBS and its nanocomposites with GPE. In order to further analyze the distribution of graphene we recorded TEM images of unstained samples (Figure S1). In this case the phase separation in the copolymer could not be observed but the images provide information on filler distribution. We focused on samples with graphene contents of 1.0 vol. % GPE or higher where graphene islands are uniformly distributed throughout the whole polymer matrix (Figure 1, main text). Both TEM images in Figure S1 confirm a good dispersion of the filler in the matrix. In the sample with higher filler content, 2.5 vol. %, regions of polymer matrix are intercalated between graphene sheets. These sheets are somewhat wrinkled and folded laminates (100-500 nm length), well distributed individually with a very small amount
of aggregates. These observations were also assessed by X-ray diffraction at wide angle carried out on SEBS and two nanocomposites of low and high graphene contents that showed no trace of a maximum associated to an interlayer spacing between graphene laminates.
Figure S1. TEM images of unstained samples of SEBS-GPE3 (A) and SEBS-GPE4 (B). As discussed in the main text, the phase separation in the block copolymer is clearly observed when one of them (the styrenic one) is stained with ruthenium tetroxide. However, under these conditions the contrast with graphene laminates becomes poor and it is hard to visualize their distribution in the matrix especially for low graphene content.
Figure S2 shows a high magnification TEM image of a stained
nanocomposite with high content of graphene (2.5 vol. % GPE), where some laminates can be clearly distinguished. Here, the filler appears as few-layer graphene composed of 4 to 8 laminates stacks and not dispersed as individual sheets. This fact does not put into question the good filler dispersion, but only reflects that a low contrast does not allow observing single laminates. From Figure S2 it can also be
suggested that the laminates are principally located in the ethylenic phase (bright area). However, the large filler size (from hundreds of nanometers to microns along the graphene plane) as compared to the distance among styrenic domains in SEBS (tens of nanometers) does not rule out a certain steric interaction of the laminates with such domains or interphases.
Figure S2. High magnification TEM image of SEBS-GPE4 stained with ruthenium tetroxide
Figure S3. Peak separation analysis of the Lorentz-corrected diffraction intensity profiles (black lines) for SEBS (left) and SEBS-GPE3 (right) of Figures 4A and 4D respectively. SAXS profiles were fitted to a number of Pearson VII curves (red lines) using the PeakFit® program (Systat Software Inc.).
