Cyclic polymers inherently do not have chain ends, and as a consequence they demonstrate unique physical properties. For example, in many cases the density, refractive index, Tg, and surface properties of cyclic polymers differ from that of their linear analogs. Despite interest from both a fundamental and applied perspective, the efficient synthesis of high molecular weight cyclic polymers remains a challenge even after many decades. The problem persists largely because tying two ends of a large molecule together is entropically unfavorable. Ring closing of large chains requires high dilution to reach completion, and intermolecular cross coupling of two separate chains inevitably leads to linear byproducts that are difficult to remove. These challenges limit the large-scale preparation of cyclic polymers. Thus, a longstanding general challenge in polymer chemistry is to synthesize cyclic polymers efficiently, with diverse compositions, high purity, and high molecular weights from readily available monomers. In 2013, we reported the synthesis and characterization of the new highly active tungsten-based catalyst for the polymerization of alkynes to give cyclic polyenes. This seminar will relate the application of the catalyst towards the synthesis of cyclic versions of important commodity polymers. Included in the presentation is the synthesis of cyclic polypropylene, cyclic polystyrene, and the highly transparent material cyclic polymethylpentene (TPXTM).

Synthesis and characterization commercially relevant cyclic polymers

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.