Evolution of Copolymers of Epoxides and CO: Catalysts, Monomers, Architectures, and Applications.

The copolymerization of CO and epoxides presents a transformative approach to converting greenhouse gases into aliphatic polycarbonates (CO-PCs), thereby reducing the polymer industry's dependence on fossil resources. Over the past 50 years, a wide array of metallic catalysts, both heterogeneous and homogeneous, have been developed to achieve precise control over polymer selectivity, sequence, regio-, and stereoselectivity. This review details the evolution of metal-based catalysts, with a particular focus on the emergence of organoborane catalysts, and explores how these catalysts effectively address kinetic and thermodynamic challenges in CO/epoxides copolymerization.

Aqueous Developable and CO-Sourced Chemical Amplification Photoresist with High Performance.

Seeking high-performance photoresists is an important item for semiconductor industry due to the continuous miniaturization and intelligentization of integrated circuits. Polymer resin containing carbonate group has many desirable properties, such as high transmittance, acid sensitivity and chemical formulation, thus serving as promising photoresist material. In this work, a series of aqueous developable CO-sourced polycarbonates (CO-PCs) were produced via alternating copolymerization of CO and epoxides bearing acid-cleavable cyclic acetal groups in the presence of tetranuclear organoborane catalyst.

Insights into the Distinct Behaviors between Bifunctional and Binary Organoborane Catalysts through Terpolymerization of Epoxide, CO, and Anhydride.

Alkyl borane compounds-mediated polymerizations have expanded to Lewis pair polymerization, free radical polymerization, ionic ring-opening polymerization, and polyhomologation. The bifunctional organoborane catalysts that contain the Lewis acid and ammonium or phosphonium salt in one molecule have demonstrated superior catalytic performance for ring-opening polymerization of epoxides and ring-opening copolymerization of epoxides and CO than their two-component analogues, i.e.

A novel mini-retractor for retroperitoneal laparoscopic partial nephrectomy.

Background: Retroperitoneal partial nephrectomy (RLPN) is the premier treatment for localized renal tumors despite narrow operation space. Many efforts have been taken to facilitate the operation of RLPN, but the optimal resolution remains debatable.

Objective: To explore the feasibility of using Mini-lap to improve workspace and surgical vision in RLPN.

Metabolic heterogeneity in clear cell renal cell carcinoma revealed by single-cell RNA sequencing and spatial transcriptomics.

Background: Clear cell renal cell carcinoma is a prototypical tumor characterized by metabolic reprogramming, which extends beyond tumor cells to encompass diverse cell types within the tumor microenvironment. Nonetheless, current research on metabolic reprogramming in renal cell carcinoma mostly focuses on either tumor cells alone or conducts analyses of all cells within the tumor microenvironment as a mixture, thereby failing to precisely identify metabolic changes in different cell types within the tumor microenvironment.

Methods: Gathering 9 major single-cell RNA sequencing databases of clear cell renal cell carcinoma, encompassing 195 samples.

Organoboron-mediated polymerizations.

The scientific community has witnessed extensive developments and applications of organoboron compounds as synthetic elements and metal-free catalysts for the construction of small molecules, macromolecules, and functional materials over the last two decades. This review highlights the achievements of organoboron-mediated polymerizations in the past several decades alongside the mechanisms underlying these transformations from the standpoint of the polymerization mode. Emphasis is placed on free radical polymerization, Lewis pair polymerization, ionic (cationic and anionic) polymerization, and polyhomologation.

A Binary Silicon-Centered Organoboron Catalyst with Superior Performance to That of Its Bifunctional Analogue.

This work reported that a silicon-centered alkyl borane/ammonium salt binary (two-component) catalyst exhibits much higher activity than its bifunctional analogue (one-component) for the ring-opening polymerization of propylene oxide, showing 7.3 times the activity of its bifunctional analogue at a low catalyst loading of 0.01 mol %, and even 15.

Sequence-Reversible Construction of Oxygen-Rich Block Copolymers from Epoxide Mixtures by Organoboron Catalysts.

Switchable catalysis, in combination with epoxide-involved ring-opening (co)polymerization, is a powerful technique that can be used to synthesize various oxygen-rich block copolymers. Despite intense research in this field, the sequence-controlled polymerization from epoxide congeners has never been realized due to their similar ring-strain which exerts a decisive influence on the reaction process. Recently, quaternary ammonium (or phosphonium)-containing bifunctional organoboron catalysts have been developed by our group, showing high efficiency for various epoxide conversions.

Highly Selective Preparation and Depolymerization of Chemically Recyclable Poly(cyclopentene carbonate) Enabled by Organoboron Catalysts.

Poly(cyclopentene carbonate) (PCPC) produced by copolymerization of CO and cyclopentene oxide (CPO) is a promising but challenging chemical recyclable polymer that has high potential in minimizing plastic pollution and maximizing CO utilization. Currently, problems remain to be solved, include low reactivity of toxic metal catalysts, inevitable byproducts, and especially the ambiguous mechanism understanding. Herein, we present the first metal-free access to PCPC by using a series of modular dinuclear organoboron catalysts.

One-Pot Construction of Sulfur-Rich Thermoplastic Elastomers Enabled by Metal-Free Self-Switchable Catalysis and Air-Assisted Coupling.

Construction of well-defined sulfur-rich macromolecules in a facile manner is an interesting but challenging topic. Herein, we disclose how to readily construct well-defined triblock sulfur-rich thermoplastic elastomers via a self-switchable isothiocyanate/episulfide copolymerization and air-assisted oxidative coupling strategy. During self-switchable polymerization, alternating copolymerization of isothiocyanate and episulfide occurs initially due to the lower energy barrier for isothiocyanate insertion with respect to successive episulfide ring-opening.

Modular Organoboron Catalysts Enable Transformations with Unprecedented Reactivity.

ConspectusElectron-deficient boron-based catalysts with metal-free but metallomimetic characteristics provide a versatile platform for chemical transformations. However, their catalytic performance is usually lower than that of the corresponding metal-based catalysts. Furthermore, many elaborate organoboron compounds are produced via time-consuming multistep syntheses with low yields, presenting a formidable challenge for large-scale applications of these catalysts.

Record Productivity and Unprecedented Molecular Weight for Ring-Opening Copolymerization of Epoxides and Cyclic Anhydrides Enabled by Organoboron Catalysts.

Producing polyesters with high molecular weight (M ) through ring-opening copolymerization (ROCOP) of epoxides with cyclic anhydrides remains a major challenge. Herein, we communicate a metal-free, highly active, and high thermoresistance system for the ROCOP of epoxides with cyclic anhydrides to prepare polyesters (13 examples). The organoboron catalysts can endure a reaction temperature as high as 180 °C for the ROCOP of cyclohexane oxide (CHO) with phthalic anhydride (PA) without the observation of any side reactions.

Pinwheel-Shaped Tetranuclear Organoboron Catalysts for Perfectly Alternating Copolymerization of CO and Epichlorohydrin.

The copolymerization of carbon dioxide (CO) and epoxides to produce aliphatic polycarbonates is a burgeoning technology for the large-scale utilization of CO and degradable polymeric materials. Even with the wealth of advancements achieved over the past 50 years on this green technology, many challenges remain, including the use of metal-containing catalysts for polymerization, the removal of the chromatic metal residue after polymerization, and the limited practicable epoxides, especially for those containing electron-withdrawing groups. Herein, we provide kinds of pinwheel-shaped tetranuclear organoboron catalysts for epichlorohydrin/CO copolymerization with >99% polymer selectivity and quantitative CO uptake (>99% carbonate linkages) under mild conditions (25-40 °C, 25 bar of CO).

Precisely Alternating Copolymerization of Episulfides and Isothiocyanates: A Practical Route to Construct Sulfur-Rich Polymers.

The development of a controlled and reliable method to construct well-defined sulfur-containing polymers has sparked great interest in polymer science. Herein, we present the trial on the copolymerization of isothiocyanates with episulfides in the presence of organic onium salts, which provides direct access to a class of sulfur-rich polymers. This methodology has combined advantages of simple operation, no metals, mild conditions (25-100 °C), controlled polymerization performance ( > 10 g mol, < 1.

Scalable, Durable, and Recyclable Metal-Free Catalysts for Highly Efficient Conversion of CO to Cyclic Carbonates.

A series of highly active organoboron catalysts for the coupling of CO and epoxides with the advantages of scalable preparation, thermostability, and recyclability is reported. The metal-free catalysts show high reactivity towards a wide scope of cyclic carbonates (14 examples) and can withstand a high temperature up to 150 °C. Compared with the current metal-free catalytic systems that use mol % catalyst loading, the catalytic capacity of the catalyst described herein can be enhanced by three orders of magnitude (epoxide/cat.

Crosslinked Resin-Supported Bifunctional Organocatalyst for Conversion of CO into Cyclic Carbonates.

The development of solvent-free, metal-free, recyclable organic catalysts is required for the current chemical fixation of carbon dioxide converted into cyclic carbonates. With the goal of reducing the cost, time, and energy consumption for the coupling reaction of CO and epoxides, a series of highly active heterogeneous catalysts, based on a thiourea and quaternary ammonium salt system, are synthesized by using a thiol-ene click reaction under ultraviolet light. Benefitting from synergistic interactions of the electrophilic center (thiourea) and the nucleophilic site (ammonium bromide), the catalysts exhibit excellent catalytic selectivity (99 %) for the cycloaddition of carbon dioxide with a diverse range of epoxides under mild conditions (1.

High-Activity Organocatalysts for Polyether Synthesis via Intramolecular Ammonium Cation Assisted S 2 Ring-Opening Polymerization.

This manuscript describes a kind of bifunctional organocatalyst with unprecedented reactivity for the synthesis of polyethers via ring-opening polymerization (ROP) of epoxides under mild conditions. The bifunctional catalyst incorporates two 9-borabicyclo[3.3.

Scalable Bifunctional Organoboron Catalysts for Copolymerization of CO and Epoxides with Unprecedented Efficiency.

The metallic catalyst-dominated alternating copolymerization of CO and epoxides has flourished for 50 years; however, the involved multistep preparation of the catalysts and the necessity to remove the colored metal residue in the final product present significant challenges in scalability. Herein, we report a series of highly active metal-free catalysts featured with an electrophilic boron center and a nucleophilic quaternary ammonium halide in one molecule for copolymerization of epoxides and CO. The organocatalysts are easily scaled up to kilogram scale with nearly quantitative yield via two steps using commercially available stocks.

Bioinspired Block Copolymer for Mineralized Nanoporous Membrane.

Homoporous membranes fabricated by self-assembled block copolymers (BCPs) have gained growing attention for their easy availability of well-ordered nanostructures for precise separation. However, it remains a challenges to improve the mechanical integrity, hydrophilic properties, and pore functionalities of the existing systems. To this end, we report an organic-mineral composite hybrid nanoporous BCP membrane with attractive superhydrophilicity, mechanical stability, and fouling-resistance derived from a bioinspired block copolymer, poly(propylene carbonate)- block-poly(4-vinylcatechol acetonide) (PPC- b-PVCA).

Directed Self-Assembly of Polystyrene-b-poly(propylene carbonate) on Chemical Patterns via Thermal Annealing for Next Generation Lithography.

Directed self-assembly (DSA) of block copolymers (BCPs) combines advantages of conventional photolithography and polymeric materials and shows competence in semiconductors and data storage applications. Driven by the more integrated, much smaller and higher performance of the electronics, however, the industry standard polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) in DSA strategy cannot meet the rapid development of lithography technology because its intrinsic limited Flory-Huggins interaction parameter (χ). Despite hundreds of block copolymers have been developed, these BCPs systems are usually subject to a trade-off between high χ and thermal treatment, resulting in incompatibility with the current nanomanufacturing fab processes.

Bis(oxazolinyl)phenyl-ligated rare-earth-metal complexes: highly regioselective catalysts for cis-1,4-polymerization of isoprene.

NCN-pincer (S,S)-2,6-bis(4'-isopropyl-2'-oxazolinyl)phenyl-ligated rare-earth-metal dichlorides [(S,S)-Phebox-(i)Pr]LnCl2(THF)2 (Ln = Sc (1); Y (2); Dy (3); Ho (4); Tm (5); Lu (6)) were synthesized via transmetalation between [(S,S)-Phebox-(i)Pr]Li and LnCl3 in THF solvent. Interestingly, treatment of LaCl3 by the same method generated tris(ligand) lanthanum complex [(S,S)-Phebox-(i)Pr]3La (7). Molecular structures of complexes 1, 2, 3, and 7 were established by single-crystal X-ray diffraction study.

Nanoparticle-assisted high photoconductive gain in composites of polymer and fullerene.

Polymer-inorganic nanocrystal composites offer an attractive means to combine the merits of organic and inorganic materials into novel electronic and photonic systems. However, many applications of these composites are limited by the solubility and distribution of the nanocrystals in the polymer matrices. Here we show that blending CdTe nanoparticles into a polymer-fullerene matrix followed by solvent annealing can achieve high photoconductive gain under low applied voltages.

Probing the viscoelastic response of glassy polymer films using atomic force microscopy.

The mechanical properties of glassy films and glass surfaces have been studied using an atomic force microscope (AFM) through various imaging modes and measuring methods. In this paper, we discuss the viscoelastic response of a glassy surface probed using an AFM. We analyzed the force-distance curves measured on a glassy film or a glassy surface at temperatures near the glass transition temperature, Tg, using a Burgers model.