Metathesis Cyclopolymerization of 1,6-Heptadiyne Derivative toward Triphenylamine-Functionalized Polyacetylene with Excellent Optoelectronic Properties and Nanocylinder Morphology

Metathesis cyclopolymerization of 1,6-heptadiyne derivatives is readily utilized to synthesize triphenylamine-functionalized polyacetylenes (TPA-PAs) by a third-generation Grubbs catalyst, which selectively generated TPA-PAs with a five-membered ring and all<i>-trans</i> microstructure. The TPA pendants endowed PAs with good solubility and excellent optoelectronic properties (maximum absorption wavelength of 592–605 nm in CHCl₃, HOMO level of around −5.04 eV, and energy bandgap of 1.82–1.77 eV). When bis-TPA side group was introduced into the PA backbone, the resultant polymer, poly­(<b>M2</b>), displayed desirable oxidative stability (up to 30 days stored in THF) and high fluorescence quantum yield (up to 12.3%) in the family of PA derivatives. In addition, poly­(<b>M2</b>) could spontaneously self-assemble into the nanocylinder architecture without requiring any tedious postsynthetic treatments. This is the first report that the rigid and immobile conjugated PA segment assembled into the novel cylindrical nanostructure with the aid of π–π interaction of TPA side group

Metathesis Cyclopolymerization of Imidazolium-Functionalized 1,6-Heptadiyne toward Polyacetylene Ionomer

Metathesis cyclopolymerization (MCP) of ionic 1,6-heptadiyne is successfully applied to synthesize polyacetylene (PA) ionomer in different solvents especially in imidazolium-based ionic liquid (IL), and MCP of ionic monomer in the mixture of THF/IL proceeded in a controlled manner by the action of Grubbs second and third generation catalysts (<b>Ru–II</b>, <b>Ru–III</b>). The influence of catalysts and solvents on polymerization behavior and chain microstructure was investigated, and the results revealed that the isolated polymer yield could reach to 97% and 82% by <b>Ru–III</b> and <b>Ru–II</b>, respectively, in 1:2 THF/IL after optimization, and PAs incorporating imidazolium pendent contained ≥95% five-membered-ring structure and almost all <i>trans-</i>double bonds along the backbone. PAs formed in different solvents reflected significant variance in optical absorption properties, and a bathochromic shift effect was observed with the mixture of THF/IL

Multiresponsive Supramolecular Gel Based on Pillararene-Containing Polymers

A multiresponsive supramolecular gel was constructed based on a bis­(pyridinium) dication guest and a copolymer with pillararenes as the pendant groups, which was synthesized by free radical copolymerization of methacrylate-functionalized pillararenes and methyl methacrylate. The mechanism of gel formation was explored by the intensive study. Upon addition of competitive host or guest molecules, pillararene-based gel could be transferred into sol due to the competition of host–guest complexation. Surprisingly, the ordered stacking of pillararenes was indispensable to obtain the supramolecular gel, which endowed the system with response to temperature change

Rational Design and Modification of High‑<i>k</i> Bis(double-stranded) Block Copolymer for High Electrical Energy Storage Capability

High dielectric constant (high-<i>k</i>) polymers have important application in advanced electronic devices such as energy storage, wearable electronics, artificial muscles, and electrocaloric cooling because of their excellent flexibility and ease of processing. However, most of the commercially available polymers have low-<i>k</i> values and the designed strategies for enhancing <i>k</i> are usually at the cost of the increase of dielectric loss. In this work, novel high-<i>k</i> and low loss bis­(double-stranded) block copolymers, containing the ionic-conjugated hybrid conductive segments (HCS) with narrow band gap and the insulating segments with wide band gap, were synthesized by tandem metathesis polymerizations. The novel copolymers exhibited enhanced dielectric constant of 33–28 accompanied by low dielectric loss of 0.055–0.02 at 10²–10⁶ Hz, and thus greatly increased stored energy density of 9.95 J cm^–3 was achieved at relatively low electric field of 370 MV m^–1, which is significantly higher than that of the commercial biaxially oriented polypropylene (BOPP) (about 1.6 J cm^–3 at 400 MV m^–1). In addition, by doping with I₂, the <i>k</i> values of the HCS-contained block copolymer can increase further to 36.5–29 with low dielectric loss of 0.058–0.026, and the stored energy density maintained at a high level of 8.99 J cm^–3 at 300 MV m^–1 with suitable I₂ content. The excellent dielectric and energy storage capability were attributed to the unique macromolecular structure and well-defined nanomorphology, which not only enhanced the dipolar, electronic, and interfacial polarizations but also significantly suppressed the leakage current and increased the breakdown strength by wrapping the narrow band gap segments in the wide band gap segments