Thermally and Base-Triggered "Debond-on-Demand" Chain-Extended Polyurethane Adhesives

A series of novel chain-extended polyurethanes (CEPUs) featuring degradable sulfonyl ethyl urethane chain-extenders that permit degradation under base-triggered conditions to afford "debond-on-demand" elastomeric adhesives are reported. Exposure of the CEPUs to tetra-butylammonium fluoride (TBAF) triggered the degradation of the sulfonyl ethyl urethane chain-extenders. Lap shear adhesion tests of the CEPUs exposed to TBAF revealed reductions in shear strength of up to 65% for both aluminum and glass substrates, from 2.18 to 0.76 MPa and from 1.13 to 0.52 MPa, respectively. The selective depolymerization of these polymers makes them suitable candidates as debondable binders for inkjet inks and coatings, enabling removal of inks and adhesive residues from substrates before they enter the recycling process, to prevent surface contaminants decreasing the quality of the recycled material.

A bioactive sprite: Recent advances in the application of vinyl sulfones in drug design and organic synthesis

Vinyl sulfones, with their exceptional chemical properties, are known as the "chameleons" of organic synthesis and are widely used in the preparation of various sulfur-containing structures. However, their most alluring feature lies in their biological activity. The vinyl sulfone skeleton is ubiquitous in natural products and drug molecules and boasts a unique molecular structure and drug activity when compared to conventional drug molecules. As a result, vinyl sulfones have been extensively studied, playing a critical role in organic synthesis and pharmaceutical chemistry. In this review, we present a comprehensive analysis of the recent applications of vinyl sulfone structures in drug design, biology, and chemical synthesis. Furthermore, we explore the prospects of vinyl sulfones in diverse fields, offering insight into their potential future applications.

Poly(ether)s derived from oxa-Michael polymerization: a comprehensive review

Poly(ether)s represent an important class of polymers and are typically formed by ring-opening polymerization, Williamson ether synthesis, or self-condensation of alcohols. The oxa-Michael reaction presents another method to form poly(ether)s with additional functional groups in the polymer backbone starting from di- or triols and electron deficient olefins such as acrylates, sulfones, or acrylamides. However, research on oxa-Michael polymerization is still limited. Herein, we outline the principles of the oxa-Michael polymerization and focus on the synthesis and preparation of poly(ether-sulfone)s, poly(ether-ester)s, poly(ether)s, and poly(ether-amide)s. Further, challenges as well as future perspectives of the oxa-Michael polymerization are discussed.

Graphical abstract

Vinyl mercaptoethanol as a reactive monomer for the preparation of functional homo- and copolymers with (meth)acrylates

Vinyl mercaptoethanol is a scalable vinyl thioether monomer, which can readily be polymerized in a free radical process or by controlled methods. It tends to form alternating copolymers if copolymerized with acrylates and methacrylates.

Polymers from S-vinyl monomers: reactivities and properties

This review summarises the work of several decades on the polymerisation of S-vinyl monomers, ranging from the early reports of suitable polymerisation techniques for these monomers to their recent renaissance in various applications.

Water as a monomer: synthesis of an aliphatic polyethersulfone from divinyl sulfone and water

Using water as a monomer in polymerization reactions presents a unique and exquisite strategy towards more sustainable chemistry. Herein, the feasibility thereof is demonstrated by the introduction of the oxa-Michael polyaddition of water and divinyl sulfone. Upon nucleophilic or base catalysis, the corresponding aliphatic polyethersulfone is obtained in an interfacial polymerization at room temperature in high yield (>97%) within an hour. The polyethersulfone is characterized by relatively high molar mass averages and a dispersity around 2.5. The polymer was tested as a solid polymer electrolyte with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as the salt. Free-standing amorphous membranes were prepared by a melt process in a solvent-free manner. The polymer electrolyte containing 15 wt% LiTFSI featured an oxidative stability of up to 5.5 V vs. Li/Li⁺ at 45 °C and a conductivity of 1.45 × 10⁻⁸ S cm⁻¹ at room temperature.

This study describes the first example of the polymerization of water as one of two monomers. The obtained polymer allows for a solvent-free preparation of polymer electrolyte membranes exhibiting a high oxidative stability.

Phosphine-Catalyzed Vinylation at Low Acetylene Pressure

The vinylation of various nucleophiles with acetylene at a maximum pressure of 1.5 bar is achieved by organocatalysis with easily accessible phosphines like tri-n-butylphosphine. A detailed mechanistic investigation by quantum-chemical and experimental methods supports a nucleophilic activation of acetylene by the phosphine catalyst. At 140 °C and typically 5 mol % catalyst loading, cyclic amides, oxazolidinones, ureas, unsaturated cyclic amines, and alcohols were successfully vinylated. Furthermore, the in situ generation of a vinyl phosphonium species can also be utilized in Wittig-type functionalization of aldehydes.

Does the oxa-Michael reaction of 2-trifluoromethacrylic acid lead to fluorinated polyesters?

2-Trifluoromethacrylic acid (MAF) is a peculiar fluorinated functional monomer.