Studies On Synthesis, Structures, And Absorption Properties Of Novel Porous Materials

Organic conjugated polymers are new porous materials with large surface areas and good porosity. They have found many useful applications in areas such as catalysis, environmental protection, gas storage, and so on, and therefore relevant research has been widely performed. These polymers with phenylene and acetylenyl units possess large π-π interaction systems, and they have many advantages such as structural stability and corrosion resistant of acid-base. This thesis reports the synthesis of several kinds of novel organic conjugated microporous polymers (CMP) based on Sonogashira-Hagihara cross-coupling reactions, and the characterization and the adsorption performance for organic solvents of these samples are studied. Our work will provide useful guidance for the rational design and synthesis of novel porous materials. The main content and conclusions of this thesis are summarized as:1. A series of homocoupled conjugated microporous polymers (HCMPs) were prepared by cross-coupling polymerization of1,3,5-triethynylbenzene and1,4-diethynylbenzene. Our results show that the structures and molar ratio of monomers has a remarkable influence on the surface area, pore volume, and micropore volume of the as-synthesized HCMP samples. With the increase of molar ratio of1,3,5-triethynylbenzene to1,4-diethynylbenzene, the surface area and total pore volume increased, and this will lead to an increase in their adsorption abilities for organic solvents. However, meanwhile the micropore volume decreased for these HCMP samples, which will result in a decrease of hydrogen sorption ability for HCMPs.2. Ideally, the polymer prepared by the polymerization of1,3,5-triethynyl-benzene and1,3,5-tribromobenzene shows two-dimensional thin film structure. However, the ultrathin films are thermodynamically unstable, and they tend to roll up or aggregate. Our results show that the reaction solvents have great effect on the morphologies of the polymers. Spherical, tubular and plate-like structures were received during the polymerization by using the toluene, p-xylene, and mesitylene solvents, respectively. The polymers with different morphologies show similar adsorption performance of N2and H2. But the storage capacity for organic solvents is remarkably influenced by CMPs with different morphologies. The plate-like CMP shows best performance for the storage of organic solvents, due to obvious swelling effect.3. We synthesized CMP with film and nanotube-like morphologies by1,3,5-triethynylbenzene with1,4-dibromobenzene and1,3,5-tribromobenzene with1,4-diethynylbenzene, respectively. Our results show that the linearly1,4-diethynylbenzene and the planar1,3,5-triethynylbenzene played a role of crystallization directing agent and template agent. Both CMP samples demonstrate large BET surface area, pore volumes, and excellent surface superhydrophobicity, and they show good adsorption capacities for organic solvents.4. The elastic polymer particles with high degree of polymerization were synthesized by1,4-diethynylbenzene and1,3,5-tribromophenol.1,4-diethynylbenzene played a role as directing agents during polymerization, and the polymer particles show the morphology of hollow tubular structure. The organic solvent adsorbed in polymer samples can be separated by squeezing, when the organic solvents reached its saturation state. This physical method is simple and has good applications.