Wenlu Pan,Yuming Zhou,Man He,Xiaohai Bu,Binbin Ding,Tingyuan Huang,Shuang Huang,Shiwei Li
Novel chiral N -propargylamide based on stigmasterol (M1, HC CCH 2 NHCOCH 2 CH 2 COO-R, R = stigmasteryl) and achiral N -propargylamide based on pivalic acid (M2) were prepared and (co)polymerized with rhodium zwitterions catalyst in CHCl 3 to afford helical polyacetylenes with moderate molecular weights (8997–26777) in good yields. The polymers were characterized by Fourier transform infrared spectroscopy (FT-IR), 1 H nuclear magnetic resonance ( 1 H NMR), gel permeation chromatography (GPC). Ultraviolet–visible spectroscopy (UV–Vis) and circular dichroism (CD) absorption spectra demonstrated that the as-prepared polymers could form helical structures with a preferential helicity. The formation of hydrogen bonds of poly(M1) in CHCl 3 was investigated according to the solution sate IR spectroscopic data . The single-handed helical conformation and polymerization degree of the new-typed poly( N -propargylamide)s could be controlled by the changing the feed ratio of chiral and achiral monomers . Furthermore, the infrared emissivity values (0.536–0.798) of copolymers were investigated at 8–14 μ m by the Infrared Emissometer.
Exploration of efficient polymerization strategies is critical in polymer science. Alkyne polycyclotrimerization reactions have become powerful synthetic tools for constructing hyperbranched polyarylenes (hb-PAs). However, most of the polymerization reactions suffer from the requirement of using transition metal catalysts, and yield mixtures of 1,2,4- and 1,3,5-trisubstituted benzene isomers in their products. In this work, we provide the first example of metal-free polycyclotrimerization of internal diynes to synthesize regioregular hb-PAs. The polymerizations of trimethylsilyl-protected aromatic diynes (1a–e) proceeded smoothly in the presence of p-toluenesulfonic acid monohydrate, producing soluble hb-PAs, hb-P1a–e, with high molecular weights (Mw up to 32 200) and perfect 1,3,5-regioregularity in satisfactory yields. The degree of branching of hb-P1e was calculated to be 0.68. The polymerization reaction was insensitive to moisture and oxygen. The hb-PAs exhibited high thermal stabilities with 5% weight loss at temperatures up to 391 °C and electrochemical activities. Moreover, the hb-PAs containing tetraphenylethene moieties are weakly emissive in solution but highly fluorescent in the aggregated state, displaying aggregation-induced emission properties.
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