polyynimialisiin

Polyynimialiseen is a proposed class of conjugated polymers whose backbones feature repeating polyynic units (sequences of carbon–carbon triple bonds) linked by flexible spacers or heteroatomic junctions. The term is used in some speculative and early-stage literature to describe materials that combine the high stiffness and π-conjugation of polyynes with improved processability and structural versatility.

Structure and properties: The backbone consists of linear polyynes connected through covalent linkages; the resulting polymers are highly conjugated, which can give low optical band gaps, strong mechanical stiffness, and potential for charge transport along the chain. However, the triple bond polarity and reactivity make them susceptible to oxidation and polymer degradation; solubility depends on side chains; thermal stability varies with substituents.

Synthesis: Approaches include palladium-catalyzed cross-coupling of di- or polyfunctional alkynes, step-growth polymerization of diynes with dihalides, and post-polymerization functionalization to introduce stabilizing groups; controlling polydispersity and avoiding cross-linking are active research challenges.

Applications and status: In theory, polyynimialiseen materials could serve as molecular wires, active optoelectronic materials, or high-strength fibers. As of now, they remain mainly in the research or conceptual stage, with limited scalable synthesis and stability concerns.

See also: polyynes, polyacetylene, conjugated polymers, molecular wires.