A theoretical study is carried out to investigate the comprehensive effect of the machined roughness and fabricated textures, by solving the average Reynolds equation coupled with a mass-conservative cavitation algorithm and taking into account asperity contact. We analyzed the influence of surface roughness, which is represented by the combined root-mean-square roughness σ and surface pattern parameter γ on the optimum texture parameters including the dimple depth-over-diameter ratio and area density under hydrodynamic and mixed lubrication conditions. The results show that the effect of surface roughness on load-carrying capacity can be ignored under hydrodynamic lubrication condition. Furthermore, the optimum texture parameters under hydrodynamic lubrication condition and the optimum dimple depth-over-diameter ratio under mixed lubrication condition are determined at minimized friction coefficient, which can be taken as the same for smooth-textured surface and rough-textured surface. The corresponding minimum friction coefficient increases with increasing σ and γ, and decreasing dimple area density under mixed lubrication condition.
Sequence-controlled organometallic
polymers are prepared by regioselective
ring-opening metathesis polymerization (ROMP) of multiple-substituted
cyclooctene monomers with a built-in sequence of the metal-containing
substituents. The side-chain metal functions of these metallopolymers
are consist of metallocenes, i.e., ferrocene and ruthenocene. The
photophysical, thermal, and electrochemical properties can be finely
tailored by the metallocene sequence along the polymer chain. This
work provides fundamental understanding to unveil the structure–property
relationship of sequence-controlled metallopolymers. This highly efficient
chain-growth polymerization is expected to incorporate a variety of
metal moieties into a single organometallic polymer with site specificity,
architectural complexity, and functional versatility. The new sequence-controlled
metallopolymers are expected to provide access to materials with potential
applications for electrochemical sensing, information processing,
and magnetic materials.
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