Unimolecularly thick monosheets of vinyl polymers fabricated in metal-organic frameworks

Facile synthesis of telechelic poly(phenylene sulfide)s by means of electron-deficient aromatic sulfonium electrophiles

We report the facile synthesis of telechelic poly(phenylene sulfide) (PPS) derivatives bearing functional groups at both termini. α,ω-Dihalogenated dimethyl-substituted PPS were obtained in high yield with a high degree of end-functionalization by using soluble poly(2,6-dimethyl-1,4-phenylenesulfide) (PMPS) and 4,4'-dihalogenated diphenyl disulfide (X-DPS, X = Cl, Br) as a precursor and an end-capping agent, respectively. Further end-functionalization is achieved through cross-coupling reactions; particularly, the Kumada-Tamao cross-coupling reaction of bromo-terminated telechelic PMPS and a vinylated Grignard reagent afforded end-vinylated PMPS with thermosetting properties. This synthetic approach can be applied to the preparation of various aromatic telechelic polymers with the desired structures and functionalities.

Construction of hexagonal spindle-shaped Fe-MOFs induced by cationic copolymer and its application for effective wastewater treatment

The environment and human health are in danger due to the long-term enrichment and buildup of organic pesticides, dyes, and harmful microbes in wastewater. The development of functional materials that are efficient for treating wastewater remains a significant problem. Eco-friendly hexagonal spindle-shaped Fe-MOFs (Hs-FeMOFs) were created in this study under the influence of cationic copolymer (PMSt). The mechanism of crystal growth and development of its unique morphology were described after looking into impact factors for the ideal circumstances and being characterized by XRD, TEM, XPS, and other techniques. It revealed that Hs-FeMOFs possess an enormous supply of adsorption active sites, a strong electropositivity, and the nanometer tip. Then, typical organic pollutants, such as herbicides and mixed dyes, as well as biological pollutants bacteria, were chosen to assess its efficacy in wastewater treatment. It was discovered that the pendimethalin could be quickly removed in wastewater and the removal rate reached 100% within 10 min. In separation of mixed dyes, the retention rate of malachite green (MG) reached 92.3% in 5 min and with a minimum inhibitory concentration of 0.8 mg/mL and demonstrated strong activity due to the presence of cationic copolymers. In actual water matrix, Hs-FeMOF could also play excellent adsorption and antibacterial activity. In summary, a novel, environmentally friendly MOF material with good activity was successfully created by cationic copolymer induction. It offers a fresh approach to develop functional materials in wastewater treatment.

Thermal Transformation of Polyacrylonitrile Accelerated by the Formation of Ultrathin Nanosheets in a Metal-Organic Framework

In this study, polyacrylonitrile (PAN) nanosheets with unimolecular thickness were successfully synthesized by cross-linking polymerization in the 2D nanospaces of a metal-organic framework. In contrast to 1D and 3D analogues, crystallization could be inhibited by the topological constraint of the ultrathin 2D network structure, allowing for an efficient thermal transformation reaction of PAN. The amorphous nature of the PAN nanosheets led to an increase in the access of oxygen molecules to the polymer chains, facilitating the thermal dehydroaromatization reactions to yield a ladder polymer structure with a highly extended conjugated system. Notably, further carbonization of this ladder polymer afforded graphitic carbon with a highly ordered structure because of the well-defined precursor structure.

Fabrication of Double-Stranded Vinyl Polymers Mediated by Coordination Nanochannels

Although double-stranded structures are commonly found in biopolymers, a general and versatile methodology for fabricating double-stranded synthetic polymers has not yet been developed. Here, we report a new approach for synthesizing double-stranded polymers composed of polystyrene and poly(methyl methacrylate). We conducted crosslinking radical polymerization inside a metal-organic framework (MOF), which had one-dimensional channels with diameters similar to the thickness of two polymer chains. Effective spatial constraint within the MOF pores facilitated highly regulated crosslinking reactions between two polymer chains with extended conformations. Remarkably, the obtained double-stranded polymers were soluble in many organic solvents, even at a high crosslinking ratio (20%), unlike conventional crosslinked polymers. Notably, this stable duplex topology, which was inaccessible using previous methods, endowed the double-stranded vinyl polymers with unusual properties in the solution and bulk states. By designing the properties of the MOF nanochannels, the proposed technique can contribute to the development of a wide range of synthetic polymer duplexes.

Two-Photon 3D Printing in Metal-Organic Framework Single Crystals

Two-photon polymerization (TPP) is a micro/nano-fabrication technology for additive manufacturing, enabling 3D printing of polymeric materials using ultrafast laser pulses. In this work, two-photon polymerization is realized inside a metal-organic framework (MOF) crystal. Intricate structures are built in the porous crystal to create a microstructure-in-crystal hybrid. Furthermore, the MOF can be removed by acid treatment to release the printed structure. The two-photon polymerization inside the crystal has the potential for MOF sensing device fabrication and data storage applications. In the future development, printing different materials in the same MOF crystal for creating functional 3D devices is hoped.

Nanoconfined synthesis of conjugated ladder polymers

This review highlights recent advances in controlled synthesis of conjugated ladder polymers using templates.

Anionic Polymerization in Porous Organic Frameworks: A Strategy to Fabricate Anchored Polymers and Copolymers

An anionic mechanism is used to create polymers and copolymers as confined to, or anchored to, high-surface-area porous nanoparticles. Linear polymers with soft and glassy chains, such as polyisoprene and polymethylmethacrylate, were produced by confined anionic polymerization in 3D networks of porous aromatic frameworks. Alternatively, multiple anions were generated on the designed frameworks which bear removal protons at selected positions, and initiate chain propagation, resulting in chains covalently connected to the 3D network. Such growth can continue outside the pores to produce polymer-matrix nanoparticles coated with anchored chains. Sequential reactions were promoted by the living character of this anionic propagation, yielding nanoparticles that were covered by a second polymer anchored by anionic block copolymerization. The intimacy of the matrix and the grown-in polymers was demonstrated by magnetization transfer across the interfaces in 2D ¹ H-¹³ C-HETCOR NMR spectra.