The effect of ionic liquid containing AlCl3 catalytic systems on the microstructure and properties of polyalphaolefin based lubricants

Ionic Liquids in Metal, Photo-, Electro-, and (Bio) Catalysis

Ionic liquids (ILs) have unique physicochemical properties that make them advantageous for catalysis, such as low vapor pressure, non-flammability, high thermal and chemical stabilities, and the ability to enhance the activity and stability of (bio)catalysts. ILs can improve the efficiency, selectivity, and sustainability of bio(transformations) by acting as activators of enzymes, selectively dissolving substrates and products, and reducing toxicity. They can also be recycled and reused multiple times without losing their effectiveness. ILs based on imidazolium cation are preferred for structural organization aspects, with a semiorganized layer surrounding the catalyst. ILs act as a container, providing a confined space that allows modulation of electronic and geometric effects, miscibility of reactants and products, and residence time of species. ILs can stabilize ionic and radical species and control the catalytic activity of dynamic processes. Supported IL phase (SILP) derivatives and polymeric ILs (PILs) are good options for molecular engineering of greener catalytic processes. The major factors governing metal, photo-, electro-, and biocatalysts in ILs are discussed in detail based on the vast literature available over the past two and a half decades. Catalytic reactions, ranging from hydrogenation and cross-coupling to oxidations, promoted by homogeneous and heterogeneous catalysts in both single and multiphase conditions, are extensively reviewed and discussed considering the knowledge accumulated until now.

In-situ photo-crosslinkable elastomer based on polyalphaolefin/halloysite nanohybrid

In this research, new injectable and in situ photocurable elastomeric nanohybrids have been fabricated from polyalphaolefin (PAO) resins and halloysite nanofiller. In this regard, the co-oligomerization of long α-olefin monomers (C6, C8 and C10) with alkenol counterparts was carried out via a simple cationic route to provide OH-functionalized PAOs. The newly formed PAO type copolymer resins as well as halloysite nanoclay were then equipped with photocurable CC bonds containing an acrylate moiety. After the characterization of the final chemical substances and also of the intermediate structures, experimentally and computationally by means of Density Functional Theory (DFT) calculations, the neat treated PAO and PAO/halloysite nanohybrids were subjected to a curing process by visible light irradiation (λ ∼ 475 nm, blue light). The crosslinking efficiency of the neat resins and the formed nanohybrid was evaluated using shrinkage strain-time curves and equilibrium swelling method. The suggested nanohybrid is not only biocompatible (96 % in the MTT assay), and hydrophilic (with a water contact angle of 61°), but also exhibits an easy, fast and robust curing process with great potential for coating and sealing technologies for medical devices.

MAO- and Borate-Free Activating Supports for Group 4 Metallocene and Post-Metallocene Catalysts of α-Olefin Polymerization and Oligomerization

Modern industry of advanced polyolefins extensively uses Group 4 metallocene and post-metallocene catalysts. High-throughput polyolefin technologies demand the use of heterogeneous catalysts with a given particle size and morphology, high thermal stability, and controlled productivity. Conventional Group 4 metal single-site heterogeneous catalysts require the use of high-cost methylalumoxane (MAO) or perfluoroaryl borate activators. However, a number of inorganic phases, containing highly acidic Lewis and Brønsted sites, are able to activate Group 4 metal pre-catalysts using low-cost and affordable alkylaluminums. In the present review, we gathered comprehensive information on MAO- and borate-free activating supports of different types and discussed the surface nature and chemistry of these phases, examples of their use in the polymerization of ethylene and α-olefins, and prospects of the further development for applications in the polyolefin industry.

Chain Walking in the AlCl3 Catalyzed Cationic Polymerization of α-Olefins

Continuing efforts aimed at performing the 1-decene polymerization to low viscosity polyalphaolefins (PAO)s using a less hazardous AlCl₃ catalyst than boron-based analogs, the basic mechanisms of this system were revealed in this research. In this aspect, neat AlCl₃ and AlCl₃ /toluene were carried out to perform 1-decene polymerizations. Microstructure analyses of the as-synthesized oils revealed low molecular weight (708 vs. 1529 g/mol), kinematic viscosity (KV¹⁰⁰ =6.4 vs. 22.2 cSt), and long chain branching (82.1 vs. 84.7) of PAO from the system containing toluene solvent. Furthermore, NMR analysis confirmed various types of short chain branch (SCB) with the inclusion of toluene ring in the structure of final PAO chains. Then, to shed light on the basic mechanisms of cationic polymerization of 1-decene including: i) chain initiation, ii) chain transfer to the monomer, iii) isomerization of the carbocation via a chain walking mechanism (causes different SCB length), and iv) binding of toluene ring to the propagating PAO chain (to yield aromatic containing oligomers), molecular modeling at the DFT level was employed. The energies obtained confirmed the ease of carbocation isomerization and chain transfer mechanisms in toluene medium, which well confirms the highly branched structure experimentally obtained for related PAO.