Dynamic Bonds: Adaptable Timescales for Responsive Materials

Dynamic bonds introduce unique properties such as self-healing, recyclability, shape memory, and malleability to polymers. Significant efforts have been made to synthesize a variety of dynamic linkers, creating a diverse library of materials. In addition to the development of new dynamic chemistries, fine-tuning of dynamic bonds has emerged as a technique to modulate dynamic properties. This Review highlights approaches for controlling the timescales of dynamic bonds in polymers. Particularly, eight dynamic bonds are considered, including urea/urethanes, boronic esters, Thiol-Michael exchange, Diels-Alder adducts, transesterification, imine bonds, coordination bonds, and hydrogen bonding. This Review emphasizes how structural modifications and external factors have been used as tools to tune the dynamic character of materials. Finally, this Review proposes strategies for tailoring the timescales of dynamic bonds in polymer materials through both kinetic effects and modulating bond thermodynamics.

Propylene homopolymerization and copolymerization with ethylene by acenaphthene-based α-diimine nickel complexes to access EPR-like elastomers

A series of acenaphthene-based α-diimine nickel complexes were synthesized and subsequently used for accessing branched EPR-like elastomers with different compositions and chain structures.

100th Anniversary of Macromolecular Science Viewpoint: Engineering Supramolecular Materials for Responsive Applications-Design and Functionality

Supramolecular polymers allow access to dynamic materials, where noncovalent interactions can be used to offer both enhanced material toughness and stimuli-responsiveness. The versatility of self-assembly has enabled these supramolecular motifs to be incorporated into a wide array of glassy and elastomeric materials; moreover, the interaction of these noncovalent motifs with their environment has shown to be a convenient platform for controlling material properties. In this Viewpoint, supramolecular polymers are examined through their self-assembly chemistries, approaches that can be used to control their self-assembly (e.g., covalent cross-links, nanofillers, etc.), and how the strategic application of supramolecular polymers can be used as a platform for designing the next generation of smart materials. This Viewpoint provides an overview of the aspects that have garnered interest in supramolecular polymer chemistry, while also highlighting challenges faced and innovations developed by researchers in the field.

α-Diimine nickel complexes bearing axially bulky terphenyl and equatorially bulky dibenzobarrelene groups: synthesis, characterization and olefin polymerization studies

A new family of asymmetric α-diimine nickel complexes bearing axially and equatorially bulky groups were synthesized successfully. They exhibited high catalytic activities for ethylene polymerization and afforded ultra-high-molecular-weight elastomeric polyethylenes.

Preparation of functionalized poly(1-butene) from 1,2-polybutadiene via sequential thiol-ene click reaction and ring-opening polymerization

Poly(1-butene) is a kind of unique poly(α-olefin) material that displays exceptional creep resistance and environmental stress cracking resistance, and therefore currently finds wide application in the fields of packaging, films, pipes, etc. However, very few current researchers are paying attention to functional poly(1-butene) despite its great research significance, perhaps due to the general paucity of catalytic systems for synthesizing this material. Therefore, in the present study, we set out to develop an alternative method to prepare polar poly(1-butene)s. Specifically, 1,2-enriched poly(1,3-butadiene), used as a starting material, was partially hydrogenated to afford a quasi-poly(1-butene) polymer containing C Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> C double bonds. These double bonds were further modified by subjecting the quasi-poly(1-butene) polymer to a thiol-ene reaction in the presence of thiol compounds, and a series of polar poly(1-butene)s that bore significantly improved surface properties were obtained. By using hydroxyl-containing thiol compounds, ring-opening polymerization (ROP) of ε-caprolactone was further implemented. Here, polar poly(ε-caprolactone) was incorporated as side chains, and we were able to control the chain length by adjusting the feeding ratio. The water contact angles of the resultant polymers, i.e., those containing the poly(ε-caprolactone) side chains, were as low as 59.4°, indicating a greater hydrophilicity resulting from the incorporation of these side chains.

An alternative method for preparing functionalized poly(1-butene) from 1,2-polybutadiene via sequential thiol-ene click reaction and ring-opening polymerization is reported.