Controlled Ring-Opening Metathesis Polymerization with Polyisobutylene-Bound Pyridine-Ligated Ru(II) Catalysts

Sequestration of Ruthenium Residues via Efficient Fluorous-enyne Termination

The creation of polymers without metal contamination remains a significant challenge for metathesis-based polymerization techniques and has complicated applications in biomedical and electronic applications. This communication reports a new approach for the removal of ruthenium byproducts through the design of an enyne terminator for metathesis polymerization that contains a fluorous tag. Upon reaction of a living polymer chain with the enyne, the ruthenium center is captured as a stable sulfur-chelated complex that can be efficiently removed after a single filtration through a fluorous cartridge. Levels of ruthenium residues as determined by ICP-MS were found to depend on the monomer structure, eluting solvent, and the degree of polymerization targeted. Ruthenium residues were minimized to low ppm levels (4-75 ppm) for most samples examined and also led to the improved thermal stability of the final materials. This represents the most efficient single method for removal of ruthenium residues from metathesis polymerization products.

Organocatalytic Michael Addition as a Method for Polyisobutylene Chain-End Functionalization

Functionalization of polyolefins, in particular polyisobutylene, remains a relatively unexplored application for the Michael reaction. This work evaluates the potential of polyisobutylene acrylate (PIBA) chain-end modification via organocatalyzed thiol-Michael and aza-Michael additions. A series of chain-end functional polyisobutylene oligomers are prepared using "click" reactions of thiols or amines to PIBA in the presence of 0.02 equivalents of organocatalyst. Reaction kinetics and chain-end transformations are monitored using NMR spectroscopy and the macromolecular products are characterized by size exclusion chromatography. Further potential of this synthetic strategy is illustrated by thiol-Michael addition of thiols formed in situ via nucleophilic thiolactone ring opening. The obtained results provide an efficient method for the preparation of functional polyisobutylene oligomers that can be utilized in a broad range of potential applications.

Synthesis of norbornene derivatives and their polymers via ROMP of norbornene derivatives

Dicyclopentadiene (DCPD) is a by-product resulting from the ethylene industry, which is high yield and underused in China. A technical route of producing valuable products—norbornene derivatives and their polymers from DCPD—was proposed and studied in this research. 5-Norbornene-2,3-dicarboxylic anhydride, a downstream product of DCPD, was employed as starting material to synthesize norbornene derivatives. Norbornene derivatives, 5-norbornene-2,3-dicarboxylic acid dimethyl ester and 5-norbornene-2,3-dicarboxylic acid diphenylethyl esters, as well as their polymers have broad application prospects in many areas. Ring-opening metathesis polymerization was employed as the polymerization process, and the polymers/copolymers of norbornene derivatives were obtained successfully. The polymerization process of norbornene derivatives was investigated in detail, from which the method for controlling molecular weights and decomposition temperatures of norbornene derivatives copolymers were developed. Till now, the route of generating valuable norbornene derivatives from DCPD was completed finally.

Synthesis and supramolecular assembly of fluorinated biogenic amine recognition host polymers

Fluorine functionalized biogenic amine carrier polymers.

Flow-facilitated ring opening metathesis polymerization (ROMP) and post-polymerization modification reactions

Continuous flow facilitates ROMP reactions to prepare homopolymers and block copolymers and allows for in-line post-polymerization click modifications.

Highly active, separable and recyclable bipyridine iridium catalysts for C–H borylation reactions

Iridium complexes generated from Ir(i) precursors and PIB oligomer functionalized bpy ligands efficiently catalyzed the reaction of arenes with bis(pinacolato)diboron under mild conditions to produce a variety of arylboronate compounds.