Synthesis and Ring-Opening Metathesis Polymerization of Norbornene-Terminated Syndiotactic Polypropylene

Polyolefin graft copolymers through a ring-opening metathesis grafting through approach

A series of polyethylene-g-atactic polypropylene graft copolymers were synthesized by grafting through copolymerization of a cyclooctene terminated aPP macromonomer with cyclooctene monomer and subsequent hydrogenation.

Cycloheptyl-fused N,N,N′-chromium catalysts with selectivity for vinyl-terminated polyethylene waxes: thermal optimization and polymer functionalization

Narrowly dispersed linear polyethylenes containing high levels of vinyl end-groups are accessible using cycloheptyl-fused Cr-catalysts operating at high temperature.

C1 polymerization: a unique tool towards polyethylene-based complex macromolecular architectures

The recent developments in organoborane initiated C1 polymerization of ylides open unique horizons towards perfectly linear polymethylenes (equivalent to PE) and PE-based complex structures. This review summarizes research on conventional and newly discovered initiators/ylides, as well as initial efforts on C3 polymerization.

Structure, function, self-assembly, and applications of bottlebrush copolymers

Bottlebrush polymers are a type of branched or graft polymer with polymeric side-chains attached to a linear backbone, and the unusual architectures of bottlebrushes provide a number of unique and potentially useful properties. These include a high entanglement molecular weight, enabling rapid self-assembly of bottlebrush block copolymers into large domain structures, the self-assembly of bottlebrush block copolymer micelles in a selective solvent even at very low dilutions, and the functionalization of bottlebrush side-chains for recognition, imaging, or drug delivery in aqueous environments. This review article focuses on recent developments in the field of bottlebrush polymers with an emphasis on applications of bottlebrush copolymers. Bottlebrush copolymers contain two (or more) different types of polymeric side-chains. Recent work has explored the diverse properties and functions of bottlebrush polymers and copolymers in solutions, films, and melts, and applications explored include photonic materials, bottlebrush films for lithographic patterning, drug delivery, and tumor detection and imaging. We provide a brief introduction to bottlebrush synthesis and physical properties and then discuss work related to: (i) bottlebrush self-assembly in melts and bulk thin films, (ii) bottlebrushes for photonics and lithography, (iii) bottlebrushes for small molecule encapsulation and delivery in solution, and (iv) bottlebrush micelles and assemblies in solution. We briefly discuss three potential areas for future research, including developing a more quantitative model of bottlebrush self-assembly in the bulk, studying the properties of bottlebrushes at interfaces, and investigating the solution assembly of bottlebrush copolymers.

In situ compatibilisation of alkenyl-terminated polymer blends using cross metathesis

A whiff of diblocks is enough! Straightforward coupling of two vinyl-terminated macromolecules was achieved by cross metathesis (CM) using Grubbs' second-generation catalyst (G2) giving access to a diversity of “self-compatibilised” polymer blends. Solution blends, in the absence of G2, showed clear macrophase separation while metathesized samples no longer did. A small fraction of diblocks only proved to act as an excellent compatibilizer.

Molecular Weight Dependence of Zero-Shear Viscosity in Atactic Polypropylene Bottlebrush Polymers

A series of bottlebrush polymers with atactic polypropylene side chains were synthesized via ring-opening metathesis polymerization using Grubbs' third-generation catalyst (H₂IMes)(3-BrPy)₂(Cl)₂Ru═CHPh. Polymers were prepared with fixed side chain length and variable backbone degree of polymerization (DP) ranging from 11 to 732 (M_w = 22-1500 kg/mol) and include the largest reported polyolefin-based bottlebrush polymers. The zero-shear viscosity of each polymer sample was measured using small-amplitude oscillatory shear measurements. Power law fits of zero-shear viscosity (η₀) versus weight-average molar mass (η₀ ∼ M_w^α) revealed distinct regimes with differing molecular weight dependences. A weak dependence (α < 0.5) was observed at low molecular weight due to the increasingly compact nature of short bottlebrush polymers with the continued addition of side chains. The scaling transitioned to Rouse-like dynamics (α = 1.2) at high molecular weight as a consequence of a sphere-to-cylinder conformational change with increasing DP of the bottlebrush backbone.

Facile synthesis of chain end functionalized polyethylenes via epoxide ring-opening and thiol–ene addition click chemistry

A library of low MW chain end functionalized polyethylenes with narrow MW distributions were prepared under mild conditions.

Well-defined polyethylene molecular brushes by polyhomologation and ring opening metathesis polymerization

Well-defined polyethylene molecular brushes were synthesized, for the first time, by combining polyhomologation and ring opening metathesis polymerization (ROMP).