Preparation and Adsorption Application Study of Fluorine-containing Conjugated Microporous Polymers

Abstract

Water pollution arising from ever-growing domestic sewage and industrial organic pollutants has caused severe environmental and ecological problems in many parts of the world. It is urgent to seek appropriate ways to resolve oily wastewater and organic solvent pollution. Currently, physical adsorption is considered to be one of the most important methods to eliminate the oil contaminations in water thanks to its high efficiency and low cost. However, traditional adsorbent materials, such as activated carbon, zeolite and natural fibers, often suffer from low adsorption capacities, poor adsorption selectivity and recyclability. Thus, it is still of great importance to develop new absorbent materials for the separation and removal of oils or organic pollutants from water to address environmental issues. Conjugated microporous polymers (CMPs) are a class of organic porous polymers that have attracted extensive attention thanks to their large specific surface area, good physicochemical stability and unique extended π-conjugation along the polymer skeleton. Here we report a fluorine-containing conjugated microporous polymer (F-CMP), which was synthesized via Sonogashira cross-coupling reaction from 1,3,5-trifluoro-2,4,6-triiodobenzene and 1,3,5-triethynylbenzene. As a comparison, fluorine-free conjugated microporous polymer (H-CMP) was synthesized in the same condition from 1,3,5-tribromobenzene and 1,3,5-triethynybenzene. By introducing fluorine atom into the conjugated microporous skeleton, the contact angle of F-CMP with water reaches 145°, exhibiting excellent hydrophobicity. Nitrogen adsorption/desorption isotherms of the F-CMP show a high specific surface area of 638 m 2 •g-1 , and the pore size distribution analysis shows the existence of both micropores and macropores. It can be obtained by adsorption experiments of oil and organic solvents that the adsorption capability of F-CMP increases significantly compared with its fluorine-free counterpart with similar structural skeleton. Due to high hydrophobicity and porous properties, F-CMP shows excellent adsorption properties towards to the removal of organic solvents and oils. The adsorption capability of F-CMP towards pump oil and chloroform can reach 40 g/g and 43 g/g, respectively. Meanwhile, F-CMP shows rapid adsorption rate and excellent adsorption recyclability. Thus, F-CMP displays promising application prospects in the field of organic pollutant adsorption and environmental remediation.

Nanoarchitectured Conjugated Microporous Polymers: State of the Art Synthetic Strategies and Opportunities for Adsorption Science

“…Among these POPs, CMPs are a class of amorphous materials that permit the linking of building blocks in a π-conjugated fashion and possess 2D or 3D frameworks . They have been widely used in adsorption, − heterogeneous catalysis, − photocatalysis, , chemosensors, − energy storage, − flame retardancy, and other fields. Since CMPs possess the features of a large specific surface area, a highly delocalized π–π conjugated system, a certain degree of hydrophilicity, and variable active groups on the surface, there is a great potential for them to be used as novel sorbent materials in sorption science.…”