Liu Kairui,Hou Guangjin,Mao Jingbo,Xu Zhanwei,Yan Peifang,Li Huixiang,Guo Xinwen,Bai Shi,Zhang Z. Conrad
While numerous single atoms stabilized by support surfaces have been reported, the synthesis of in-situ reduced discrete metal atoms weakly coordinated and stabilized in liquid media is a more challenging goal. We report the genesis of mononuclear electron deficient Pt 1 (0) by reducing H 2 PtCl 6 in liquid polydimethylsiloxane-polyethylene glycol (PDMS-PEG) (Pt 1 @PDMS-PEG). UV–Vis, far-IR, and X-ray photoelectron spectroscopies evidence the reduction of H 2 PtCl 6 . CO infrared, and 195 Pt and 13 C NMR spectroscopies provide strong evidence of Pt 1 (0), existing as a pseudo-octahedral structure of (R 1 OR 2 ) 2 Pt(0)Cl 2 H 2 (R 1 and R 2 are H, C, or Si groups accordingly). The weakly coordinated (R 1 OR 2 ) 2 Pt(0)Cl 2 H 2 structure and electron deficient Pt 1 (0) have been validated by comparing experimental and DFT calculated 195 Pt NMR spectra. The H + in protic state and the Cl − together resemble HCl as the weak coordination. Neutralization by a base causes the formation of Pt nanoparticles. The Pt 1 @PDMS-PEG shows ultrahigh activity in olefin hydrosilylation with excellent terminal adducts selectivity.
Free adjustment of micro/nanophase-separation degrees in coatings is not easily accessible, which is a big handicap in the development of phase-separation-related applications. Here, by utilizing the reactivity difference between two phases, a two-step aza- Michael addition pre-crosslinking strategy, demonstrated by acryloxy-terminated polydimethylsiloxane/polyethylene glycol (PEG) blend coatings, is proposed for the first time to tune microphase separation degrees, and promote compatibility of the biphasic amphiphilic polymer blends. Followed by a systematic study of the two-step pre-crosslinking time, surface morphologies of samples with desired phase-separation degrees are unveiled using optical microscopy, AFM, and XPS. The wettability, and anti-fouling properties — for example, anti-protein and anti-marine bacterial ( Shewanella ) adhesion — of these coatings are assessed. Less protein adsorption is observed on those surfaces with lower receding water contact angles. Shewanella adhesion is efficiently discouraged by the introduction of PEG segments, but the trend evolved with surface wettability and micro/nanophase structure in a complex way.
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