A novel single-atom Ni(II) catalyst ( Ni-OH ) is covalently immobilized onto the nano-channels of mesoporous Santa Barbara Amorphous (SBA)-15 particles and isotropic Anodized Aluminum Oxide (AAO) membrane for confined-space ethylene extrusion polymerization. The presence of surface-tethered Ni complexes ( Ni@SBA-15 and Ni@AAO ) is confirmed by the inductively coupled plasma-optical emission spectrometry (ICP-OES) and X-ray photoelectron spectroscopy (XPS). In the catalytic spinning process, the produced PE materials exhibit very homogeneous fibrous morphology at nanoscale (diameter: ~50 nm). The synthesized PE nanofibers extrude in a highly oriented manner from the nano-reactors at ambient temperature. Remarkably high M w (1.62×10 6  g mol −1 ), melting point (124 °C), and crystallinity (41.8 %) are observed among PE samples thanks to the confined-space polymerization. The chain-walking behavior of surface tethered Ni catalysts is greatly limited by the confinement inside the nano-channels, leading to the formation of very low-branched PE materials (13.6/1000 C). Due to fixed supported catalytic topology and room temperature, the filaments are expected to be free of entanglement. This work signifies an important step towards the realization of a continuous mild catalytic-spinning (CATSPIN) process, where the polymer is directly synthesized into fiber shape at negligible chain branching and elegantly avoiding common limitations like thermal degradation or molecular entanglement.

Functionalization of Aluminium surfaces by phosphonic acid (PA) treatments is of key industrial importance. This work discloses the effect of PA molecular design on the performance of aqueous PA surface treatments of Aluminium under acidic conditions. Comprehensive XPS and ToF-SIMS analyses show that the “final” nature of the PA adsorbate layer is not only governed by competing in-situ PA adsorption and oxide dissolution processes, but also by modifications of the transient state of the adsorbate layer during subsequent water rinsing in air. Low-soluble organo-metallic-phosphonic (OMP) deposits formed by complexation with Al3+ ions in solution are largely removed upon water-rinsing; only few physisorbed OMP complexes are converted trans-situ to a chemisorbed state. The in-situ oxide dissolution and ex-situ re-oxidation processes are suppressed with increasing steric size of the PA molecule. Moreover, intermolecular phenyl π-π interactions can act as a driving force to increase the surface density of the PA adsorbate layer in-situ, which also effectively suppresses in-situ oxide dissolution and ex-situ re-oxidation. The findings provide profound insights on how PA molecular designs can be tuned to tailor the chemistry and morphology of PA-adsorbate layers, which may contribute to advance surface treatment strategies of Al surfaces for a wealth of applications.

The heterogeneous surface support can play a key role in determining polymer microstructure, as we show for a novel variant of Ni-catalyst from the family of late-transition metal complexes; this extends the toolbox for novel catalytic solutions in industrial processes. Novel variants of single-atom catalysts (Ni-FO-Al@SiO2, Ni-FOSi@SiO2, Ni-O-Al@SiO2, and Ni-O-Si@SiO2) were prepared in the form of unsymmetrical a-diimine Ni complexes (Ni-OH and Ni-FOH) and then characterized by inductively coupled plasma - optical emission spectrometry (ICP-OES) and X-ray photoelectron spectroscopy (XPS) analysis. Ethylene slurry-phase polymerization was performed both via self-supporting and covalent-tethering strategies to systematically study the surface confinement effects. High catalytic activity was maintained under the slurry-phase polymerization (as high as 3.9 x 106 g of PE (mol of Ni)-1 h-1). The crucial features of high molecular weight (>106 g mol-1) and high branching density (as high as 180.1BD/1000C) were found among the PE samples produced via heterogeneous polymerization. A detailed investigation suggested that surface functional groups, such as -OH and -Cl, coordinate with the active Ni species via their lone pairs and terminate the ethylene polymerization. Microstructure analysis of the PE confirm that the supporting substrate provides the chance to modulate the chain-walking behavior of these Ni catalysts. Systematic high-temperature 1H and 13C NMR analysis indicated that the PE branching density could significantly decrease by surface confinement from the solid substrate. Until now, such microstructure control has been mainly realized via the laborious synthesis of bulky a-diimine ligands.

A phosphorus-fluorine containing compound tetraphenylphosphine hexafluorophosphate (Ph4PPF6) was synthesized by one-step method and characterized by FTIR, NMR, SEM, and EDX. Epoxy resin (EP) cured with an aliphatic hardener and Ph4PPF6 as a multifunctional additive were fabricated. The combined effects of Ph4PPF6 with melamine (MEL) and copper hydroxystannate (CuHS) on the fire safety, thermal stability, smoke toxicity and dielectric performances of EP were investigated. It is found that EP containing 2 wt% P (from Ph4PPF6) combined with 10 wt% MEL (sample EP 2P 10M) and EP with 2 wt% P from Ph4PPF6 combined with 5 wt% MEL, 5 wt% CuHS (sample EP 2P 5M5C) pass V0 classification in UL-94 VB tests. The cone calorimetric tests on these composites reveal that the peak heat release rate of sample EP 2P 5M5C is reduced by 64.2% in comparison to pure EP. The toxic gases including HF, CO, HCN are reduced to different extent when MEL and CuHS used as co-additives. The dielectric loss of sample EP 2P 10M is reduced by 26.3% in comparison to pure EP.

The phosphonic acid (PA) surface treatment on various metal substrates is of high industrial relevance, and the PA molecular structure significantly affects its quality. In this work, systematic variation of the PA molecular steric and electron environment helps discern two steady-state adsorption modes on an aluminum surface. The PA molecular structure was varied systematically, which included inorganic phosphorus acid, alkyl phosphonic acids, and phenyl phosphonic acids. To explore their in situ dynamics of adsorption/desorption on the electrochemically unstable aluminum, techniques such as electrochemical impedance spectroscopy and inductively coupled plasma optical emission spectrometry were employed. A range of different types of interfacial layers are formed on the aluminum surface, namely, from the dissolution-limiting physisorbed layer to a quasi-inhibiting chemisorbed layer on the aluminum surface in acidic (pH ≈ 2.2) solution. Presented findings establish the dynamic steady-state nature of this type of interface. They reveal fundamental relationships among adsorbent steric or electronic effects, the steady-state interface morphology, and the steady-state aluminum dissolution rate. The study brings also a more differentiated molecular structure-related description of the aluminum dissolution inhibition of PAs and relates it to molecular density functional theory calculations.

A simple method is reported for the preparation of silver nanoparticle (AgNP) embedded pH-responsive hydrogel microparticle catalyst via Michael addition gelation and in-situ silver nitrate (AgNO3) reduction. The AgNPhydrogel microsphere exhibited an efficient reduction of pollutants like 4-Nitrophenol (4-NP) and Congo red (CR) under acidic medium with turn over frequency (TOF) of -170 h-1 and -124 h-1 respectively. Interestingly, the activity of the catalysts was turned-OFF under a basic medium (> pH 12) due to the deswelling pH-responsive matrix surrounding the AgNPs. On the contrary, turning-OFF the hydrogenation of a cationic pollutant like methylene blue (MB) using high pH (> 12) was not possible, due to ionic interaction of MB molecules with the negatively charged catalyst at this pH. This feature was used to demonstrate selective hydrogenation of only MB from a mixture of 4-NP and MB. Finally, five recycling steps confirmed the reusability and practical application potential of the catalyst.

Research on corrosion protection of aluminum has intensified over the past decades due to environmental concerns regarding chromate-based conversion coatings and also the higher material performance requirements in automotive and aviation industries. Phosphonic acid-based organic and organic-inorganic coatings are increasingly investigated as potential replacements of toxic and inefficient surface treatments for aluminum. In this review, we have briefly summarized recent work (since 2000) on pretreatments or coatings based on various phosphonic acids for aluminum and its alloys. Surface characterization methods, the mechanism of bonding of phosphonic acids to aluminum surface, methods for accessing the corrosion behavior of the treated aluminum, and applications have been discussed. There is a clear trend to develop multifunctional phosphonic acids and to produce hybrid organic-inorganic coatings. In most cases, the phosphonic acids are either assembled as a monolayer on the aluminum or incorporated in a coating matrix on top of aluminum, which is either organic or organic-inorganic in nature. Increased corrosion protection has often been observed. However, much work is still needed in terms of their ecological impact and adaptation to the industrially-feasible process for possible commercial exploitation.