The ability to covalently attach organic molecules to semiconductor surfaces in a controllable and selective manner is currently receiving much attention due to the potential for creating hybrid silicon-organic molecular-electronic devices. Here we use scanning tunneling microscopy (STM) and density functional theory calculations to study the adsorption of a simple ketone [acetone; (CH(3))(2)CO] to the silicon (001) surface. We show both bias and time-dependent STM images and their agreement with total energy DFT calculations, simulated STM images, and published spectroscopic data. We investigate the stability of the resulting adsorbate structures with respect to temperature and applied STM tip bias and current. We demonstrate the ability to convert from the kinetically favored single-dimer alpha-H cleavage adsorbate structure to thermodynamically favored bridge-bonded adsorbate structures. This can be performed for the entire surface using a thermal anneal or, for individual molecules, using the highly confined electron beam of the STM tip. We propose the use of the carbonyl functional group to tether organic molecules to silicon may lead to increased stability of the adsorbates with respect to current-voltage characterization. This has important implications for the creation of robust single-molecule devices.

Using density functional theory, we report detailed reaction path calculations for the reaction of acetone with the silicon (001) surface. We identify the key reaction intermediates of dissociative adsorption and the transition states between them. This resolves the identity of the one-dimer intermediate observed in STM experiments and its role in the formation of several two-dimer-wide end products of dissociation. Key to the understanding of the dissociation mechanism is the ambiphilic character of the two reactants, that is the simultaneous expression of electrophilic and nucleophilic reactivities in both the surface and the acetone molecule.

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Conventional polymer blending has a shortcoming in conductivity characteristic. This research addresses the preparation of conductive thermoplastic natural rubber (TPNR) blends with graphene nanoplates (GNPs)/polyaniline (PANI) through melt blending using an internal mixer. The effect of PANI content (10, 20, 30, and 40 wt %) on the mechanical and thermal properties, thermal and electrical conductivities, and morphology observation of the TPNR/GNPs/PANI nanocomposites was investigated. The results showed that the tensile and impact properties as well as thermal conductivity of nanocomposite had improved with the incorporation of 3 wt % of GNPs and 20 wt % of PANI as compared to neat TPNR and reduced with further increase of the PANI content. It was observed that the GNPs and PANI acted as a critical component to improve the thermal stability and electrical conductivity of the TPNR/GNPs/PANI nanocomposites. The most improved conductivity of 5.22 E‐5 S/cm was observed at 3 wt % GNPs and 40 wt % PANI. Variable‐pressure scanning electron microscopy micrograph revealed the good interaction and distribution of GNPs and PANI within TPNR matrix at PANI loadings lower than 30 wt %. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48873.

The thermal conductivity and mechanical performance of a hybrid multi‐walled carbon nanotubes/silicon carbide (MWCNTs/SiC)‐reinforced thermoplastic natural rubber (TPNR) nanocomposite were investigated. TPNR was fabricated from polypropylene, natural rubber (NR) and liquid NR at a volume ratio of 70:20:10, respectively. The Young's modulus, the tensile strength, and the storage and loss modulus of the nanocomposites with a single filler of MWCNTs or SiC were enhanced compared with those of neat TPNR. The greatest improvements in these properties were achieved at a composition of 1.5 wt% SiC‐1.5 wt% MWCNTs‐reinforced nanocomposite. In addition, the thermal conductivity and specific heat capacity of the nanocomposites, determined using a laser flash technique, were improved in the 3 wt% SiC‐reinforced nanocomposite sample relative to those of the pure sample and the other reinforced nanocomposites. Based on these findings, MWCNTs and SiC could serve as suitable percolated networks of hybrid reinforcement fillers to achieve optimal thermal and mechanical properties in the TPNR matrix. POLYM. COMPOS., 40:E695–E703, 2019. © 2018 Society of Plastics Engineers