Theoretical Study of Ethylene−Vinyl Acetate Free-Radical Copolymerization: Reactivity Ratios, Penultimate Effects, and Relative Rates of Chain Transfer to Polymer

Diverse functional polyethylenes by catalytic amination

Functional polyethylenes possess valuable bulk and surface properties, but the limits of current synthetic methods narrow the range of accessible materials and prevent many envisioned applications. Instead, these materials are often used in composite films that are challenging to recycle. We report a Cu-catalyzed amination of polyethylenes to form mono- and bifunctional materials containing a series of polar groups and substituents. Designed catalysts with hydrophobic moieties enable the amination of linear and branched polyethylenes without chain scission or cross-linking, leading to polyethylenes with otherwise inaccessible combinations of functional groups and architectures. The resulting materials possess tunable bulk and surface properties, including toughness, adhesion to metal, paintability, and water solubility, which could unlock applications for functional polyethylenes and reduce the need for complex composites.

Connecting Gas-Phase Computational Chemistry to Condensed Phase Kinetic Modeling: The State-of-the-Art

In recent decades, quantum chemical calculations (QCC) have increased in accuracy, not only providing the ranking of chemical reactivities and energy barriers (e.g., for optimal selectivities) but also delivering more reliable equilibrium and (intrinsic/chemical) rate coefficients. This increased reliability of kinetic parameters is relevant to support the predictive character of kinetic modeling studies that are addressing actual concentration changes during chemical processes, taking into account competitive reactions and mixing heterogeneities. In the present contribution, guidelines are formulated on how to bridge the fields of computational chemistry and chemical kinetics. It is explained how condensed phase systems can be described based on conventional gas phase computational chemistry calculations. Case studies are included on polymerization kinetics, considering free and controlled radical polymerization, ionic polymerization, and polymer degradation. It is also illustrated how QCC can be directly linked to material properties.

Poly(vinyl acetate-co-ethylene) particles prepared by surfactant-free emulsion polymerization in the presence of a hydrophilic RAFT/MADIX macromolecular chain transfer agent

Poly(vinyl acetate-co-ethylene) latexes are prepared under a broad range of conditions by emulsion polymerization in the presence of a hydrophilic RAFT/MADIX macromolecular chain transfer agent.

“Breathing” unimolecular micelles based on a novel star-like amphiphilic hybrid copolymer

Novel unimolecular micelles that possess a pH-induced “breathing” feature are presented in this paper.

Unimolecular micelles composed of inner coil-like blocks and outer rod-like blocks crafted by combination of living polymerization with click chemistry

Star-shaped PS-b-P3HT was synthesized via a combination of ATRP, GRIM polymerization, and click reaction. They possessed different properties as compared to their linear analogues

A Quantum-Chemical Approach to Understanding Reversible Addition Fragmentation Chain-Transfer Polymerization

This article highlights some of the recent contributions that computational quantum chemistry has made to the understanding of the reversible addition fragmentation chain transfer (RAFT) polymerization process. These include recent studies of rate retardation in cumyl dithiobenzoate mediated polymerization of styrene and methyl acrylate and the xanthate mediated polymerization of vinyl acetate, and studies of the effects of substituents on the addition and fragmentation reactions in prototypical systems and polymer-related systems. The accuracy and applicability of theoretical procedures for studying free-radical polymerization are also discussed, and the methodology is evaluated using the homopropagation rate coefficient of methyl acrylate as a test case. The review concludes with a brief discussion of possible future developments in the field.