Synthesis, properties, and material hybridization of bare aromatic polymers enabled by dendrimer support

Synthesis of Interlocked and Non-Interlocked Deca(para-phenylene) Derivatives by Ni-mediated Biaryl Coupling

Oligo(para-phenylene) (PPn) is a compound composed of directly connected 1,4-phenylene moieties. The synthesis of PPn composed of six or more phenylene moieties with no substituent at the internal phenylene moiety has been challenging because of its low solubility. Herein we synthesized oligo(para-phenylene)[2]rotaxanes, including a deca(para-phenylene)[2]rotaxane, with a defined number of phenylene moieties. Biaryl coupling of iodoarenes mediated by macrocyclic dibenzodihydrophenanthroline-Ni complex was utilized for the first time to synthesize the [2]rotaxanes. Compared to the non-interlocked deca(para-phenylene), the deca(para-phenylene)[2]rotaxane showed higher solubility. The properties of the oligo(para-phenylene)[2]rotaxanes and non-interlocked oligo(para-phenylene)s were analyzed by spectroscopic methods.

Simultaneously Suppressing the Coffee Ring Effect of Solutes with Different Sizes

Suppressing the coffee ring effect (CRE), which improves the uniformity of deposition, has attracted great attention. Usually, a realistic system contains solutes of various sizes. Large particles preferentially settle onto the substrate under gravity, separated from small particles even when CRE is suppressed, which generates nonuniformity in another way. This hinders small particles from filling the gaps at the deposition-substrate interface, leaving a frail deposition. Here, the CRE of polydispersed solutes is simultaneously suppressed, and a more uniform deposition is achieved by suspending the drop together with adding trace amounts of cations. The gaps tend to be filled, which makes the deposition bind more tightly. Analysis shows that gravity coordinates with the interactions that mediate the attraction between particles and the substrate, resulting in the coinstantaneous adsorption of all particles. This work adds another dimension to the suppression of CRE, improving the uniformity of deposition in complex systems and paving the way for the development of techniques in diverse manufacturing industries.

Living Suzuki-Miyaura Catalyst-Transfer Polymerization for Precision Synthesis of Length-Controlled Armchair Graphene Nanoribbons and Their Block Copolymers

The bottom-up synthesis of graphene nanoribbons (GNRs) offers a promising approach for designing atomically precise GNRs with tuneable photophysical properties, but controlling their length remains a challenge. Herein, we report an efficient synthetic protocol for producing length-controlled armchair GNRs (AGNRs) through living Suzuki-Miyaura catalyst-transfer polymerization (SCTP) using RuPhos-Pd catalyst and mild graphitization methods. Initially, SCTP of a dialkynylphenylene monomer was optimized by modifying boronates and halide moieties on the monomers, affording poly(2,5-dialkynyl-p-phenylene) (PDAPP) with controlled molecular weight (M_n up to 29.8k) and narrow dispersity (Đ = 1.14-1.39) in excellent yield (>85%). Subsequently, we successfully obtained N = 5 AGNRs by employing a mild alkyne benzannulation reaction on the PDAPP precursor and confirmed their length retention by size-exclusion chromatography. In addition, photophysical characterization revealed that a molar absorptivity was directly proportional to the length of the AGNR, while its highest occupied molecular orbital (HOMO) energy level remained constant within the given AGNR length. Furthermore, we prepared, for the very first time, N = 5 AGNR block copolymers with widely used donor or acceptor-conjugated polymers by taking advantage of the living SCTP. Finally, we achieved the lateral extension of AGNRs from N = 5 to 11 by oxidative cyclodehydrogenation in solution and confirmed their chemical structure and low band gap by various spectroscopic analyses.

Experimental and Computational Approaches to Sulfonated Poly(arylene ether sulfone) Synthesis Using Different Halogen Atoms at the Reactive Site

Engineering thermoplastics, such as poly(arylene ether sulfone), are more often synthesized using F-containing monomers rather than Cl-containing monomers because the F atom is considered more electronegative than Cl, leading to a better condensation polymerization reaction. In this study, the reaction's spontaneity improved when Cl atoms were used compared to the case using F atoms. Specifically, sulfonated poly(arylene ether sulfone) was synthesized by reacting 4,4'-dihydroxybiphenyl with two types of biphenyl sulfone monomers containing Cl and F atoms. No significant difference was observed in the structural, elemental, and chemical properties of the two copolymers based on nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, transmission electron microscopy, and electrochemical impedance spectroscopy. However, the solution viscosity and mechanical strength of the copolymer synthesized with the Cl-terminal monomers were slightly higher than those of the copolymer synthesized with the F-terminal monomers due to higher reaction spontaneity. The first-principle study was employed to elucidate the underlying mechanisms of these reactions.