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A novel heat-curable silicone rubber (MCSR/Si-PAMAM) was prepared by using siloxane polyamidoamine (Si-PAMAM) dendrimers as cross-linkers and polysiloxane containing γchloropropyl groups as gums. The chemical cross-linking occurs through the reaction between Si-PAMAM dendrimers and polysiloxane containing γ-chloropropyl groups. The effect of various amounts of cross-linkers on mechanical properties of MCSR/Si-PAMAM was discussed in this paper. MCSR/Si-PAMAM exhibits favorable mechanical properties with a tensile strength of 10.06 MPa and a tear strength of 47.9 kN/m when the molar ratio r of [N-H]/[CH 2 CH 2 CH 2 Cl] is 1:1. These excellent mechanical properties can be attributed to the formation of concentrative cross-linking from Si-PAMAM dendrimers in the cross-linking networks, along with the introduction of Si-O-Si units in the internal structure of dendrimers. The introduction of Si-O-Si unitsreduces the steric hindrance of molecular structure, which facilitates the N-H bonds in the interior layers of dendrimers to react with γ-chloropropyl groups. In addition, thermogravimetric analysis results indicate that MCSR/Si-PAMAM is thermally stable even at high temperatures in a nitrogen atmosphere. Differential scanning calorimetry analysis reveals that the glass transition peak of MCSR/Si-PAMAM is not identified in the temperature range −150 to −30°C, only a melting endothermic peak at −40°C.

Searching for new carbon allotropes with superior properties has been a longstanding interest in material sciences and condensed matter physics. Here we identify a novel superhard carbon phase with an 18-atom trigonal unit cell in a full-sp 3 bonding network, termed tri-C18 carbon, by first-principles calculations. Its structural stability has been verified by total energy, phonon spectra, elastic constants, and molecular dynamics simulations. Furthermore, tri-C18 carbon has a high bulk modulus of 400 GPa and Vickers hardness of 79.0 GPa, comparable to those of diamond. Meanwhile, the simulated x-ray diffraction pattern of tri-C18 carbon matches well with the previously unexplained diffraction peaks found in chimney soot, indicating the possible presence of tri-C18 carbon. Remarkably, electronic band structure calculations reveal that tri-C18 carbon has a wide indirect bandgap of 6.32 eV, larger than that of cubic diamond, indicating its great potential in electronic or optoelectronic devices working in the deep ultraviolet region.

A much simpler and broadly applicable dip-coating method using silica nanoparticles and a silane coupler for preparing hydrophobic paper is presented. Both producing surface hydrophobization without additional surface treatment and increasing the adhesive force between the paper and the coated material can be realized by an almost one-step procedure. The modified filter paper could not only selectively permeate oil from a mixture, but also exhibits superior recyclability, indicating its great potential application in the oil-water separation area.

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