Synthesis of Nano-Structured Conjugated Polymers with Multiple Micro-/Meso-Pores by the Post-Crosslinking of End-Functionalized Hyperbranched Conjugated Polymers

A nano-structured conjugated polymer with multiple micro-/meso-pores was synthesized by post-crosslinking of an end-functionalized hyperbranched conjugated prepolymer. Firstly, an AB2 monomer 3-((3,5-dibromo-4-(octyloxy)phenyl)ethynyl)-6-ethynyl-9-octyl-9H-carbazole (PECz) was synthesized and polymerized by Sonogashira reaction to give the -Br end-functionalized hyperbranched conjugated prepolymer hb-PPECz. The photophysical and electrochemical properties of hb-PPECz were investigated. The λmax of absorption and emission of hb-PPECz in tetrahydrofuran (THF) solution was 313 and 483 nm, respectively. The optical energy bandgap, highest occupied molecular orbital (HOMO), and lowest unoccupied molecular orbital (LUMO) energy levels of hb-PPECz were 2.98, -5.81, and -2.83 eV, respectively. Then, the prepolymer hb-PPECz was post-crosslinked by Heck reaction with divinylbenzene to give the porous conjugated polymer c-PPECz. The effects of hb-PPECz concentration and added dispersant polyvinylpyrrolidone (PVP K-30) on the morphology and porosity of c-PPECz were investigated. The resulting c-PPECzs showed multiple porous structures mainly constructed by micropores and mesopores. Under a higher hb-PPECz concentration (4 wt/v%), a bulky gel product was obtained. Under lower hb-PPECz concentrations (0.6 wt/v%~2 wt/v%), the resulting c-PPECzs were mainly composed of nano-sized particles. Nearly spheric nanoparticles (200~300 nm) (c-PPECz-5) were obtained under the concentration of 1 wt/v% in the presence of PVP (10 wt% of hb-PPECz). The Brunauer-Emmett-Teller (BET) surface area, pore volume, average pore size, and percentage of pore size below 10 nm of c-PPECz-5 were 10.7781 m2·g-1, 0.0108 cm3·g-1, 4.0081 nm, and 94.47%, respectively.

Storing Mg Ions in Polymers: A Perspective

The electrochemical performance of rechargeable Mg batteries (RMBs) is primarily determined by the cathodes. However, the strong interaction between highly polarized Mg²⁺ and the host lattice is a big challenge for inorganic cathode materials. While endowed with weak interaction with Mg²⁺ , organic polymers are capable of fast reaction kinetics. Besides, with the advantages of light weight, abundance, low cost, and recyclability, polymers are deemed as ideal cathode materials for RMBs. Although polymer cathodes have remarkably progressed in recent years, there are still significant challenges to overcome before reaching practical application. In this perspective, the challenges faced by polymer cathodes are critically focused, followed by the retrospection of efforts devoted to design polymers. Some feasible strategies are proposed to explore new structures and chemistries for the practical application of polymer cathodes in RMBs.

Rational design of bifunctional conjugated microporous polymers

Conjugated microporous polymers (CMPs) are an emerging class of porous organic polymers that combine π-conjugated skeletons with permanent micropores. Since their first report in 2007, the enormous exploration of linkage types, building units, and synthetic methods for CMPs have facilitated their potential applications in various areas, from gas separations to energy storage. Owning to their unique construction, CMPs offer the opportunity for the precise design of conjugated skeletons and pore environment engineering, which allow the construction of functional porous materials at the molecular level. The capability to chemically alter CMPs to targeted applications allows for the fine adaptation of functionalities for the ever-changing environments and necessities. Bifunctional CMPs are a branch of functionalized CMPs that have caught the interest of researchers because of their inherent synergistic systems that can expand their applications and optimize their performance. This review discusses the rational design and synthesis of bifunctional CMPs and summarizes their advanced applications. To conclude, our own perspective on the research prospects of these types of materials is outlined.

Advances in Conjugated Microporous Polymers

Conjugated microporous polymers (CMPs) are a unique class of materials that combine extended π-conjugation with a permanently microporous skeleton. Since their discovery in 2007, CMPs have become established as an important subclass of porous materials. A wide range of synthetic building blocks and network-forming reactions offers an enormous variety of CMPs with different properties and structures. This has allowed CMPs to be developed for gas adsorption and separations, chemical adsorption and encapsulation, heterogeneous catalysis, photoredox catalysis, light emittance, sensing, energy storage, biological applications, and solar fuels production. Here we review the progress of CMP research since its beginnings and offer an outlook for where these materials might be headed in the future. We also compare the prospect for CMPs against the growing range of conjugated crystalline covalent organic frameworks (COFs).

Fabrication of a fayalite@C nanocomposite with superior lithium storage for lithium ion battery anodes

Fayalite (α-Fe₂SiO₄) with an orthorhombic crystalline structure delivers an initial discharge/charge capacity of 849.0 mA h g⁻¹/514.5 mA h g⁻¹ and a second discharge/charge capacity of 504.9 mA h g⁻¹/489.5 mA h g⁻¹ at a current rate of 0.1 C.