Synthesis Of Carbazole - Based Microporous Polymers And Their Carbon Dioxide Trapping Properties

The excessive emission of CO2 in the environment causing serious problem:the greenhouse effect. It is urgent to control the emission of carbon dioxide, in order to reduce the consequences of the greenhouse effect. The capture of CO2 has become one of the most notable problems at home and abroad. It has become one of the most direct and effective methods to select a kind of effective material to absorb carbon dioxide. Lots of research works show that microporous material with low density, high specific surface area and good pore size distribution, etc. It has a good potential application on the gas adsorption. The design and synthesis of microporous materials, especially the microporous organic polymer materials, have obtained significant scientific research achievements in resent years. By selecting appropriate monomer and reaction and catalyst, one could synthesize a kind of microporous organic polymer materials with high CO2 adsorption performance.Organic microporous polymer can be roughly divided into the following four types according to the molecular structure:hyper-crosslinked polymers (HCPs), polymers of intrinsic microporosity (PIM), covalent organic frameworks (COFs), conjugated microporous polymers (CMPs). This thesis mainly focuses on the conjugated microporous polymers and hypercrosslinked polymers. We synthesized a series of novel organic microporous polymer materials with high specific surface areas and excellent gas adsorption capacities by designing different structures of organic monomer and using different preparation strategies. The main work includes the following aspects:(1) Two polymerizable monomers of 1,3,6,8-tetrabromo-9H-carbazole and 1,3,6,8-tetrabromopyrene with tetra-functionality have been designed and synthesized, and then the ternary conjugated microporous polymers were synthesized via Suzuki cross-coupling polycondensation reacted with 1,4-phenylenediboronic acid. We studied the influences (for example, the specific surface area, pore surface area and micropore volume, etc.) of the ratio of the monomers on the terpolymer and gas (CO2, H2 and CH4, etc.) adsorption capacity of the terpolymer by adjusting the proportion of 1,3,6,8-tetrabromo-9H-carbazole and 1,3,6,8-tetrabromopyrene to adjust the structure of the polymers. In this research, we found that the terpolymer CP-CMP5 with 60 mol% 1,3,6,8-tetrabromopyrene has the highest specific surface area of 2241 m2/g in all the copolymers and the carbon dioxide adsorption capacity up to 4.57 mmol/g under the condition of 1.13 bar/273 K, which is higher than that of most reported conjugated microporous polymer materials. The terpolymers have important significance for future gas adsorption study of organic microporous polymer.(2) By selecting N,N-carbazole as building block and Friedel-Crafts alkylation reaction, we prepared a series of polymers of PBCA1-4 with high specific surface area and high carbon dioxide adsorption capacity. In this study, we choosed different catalyst, solvent and the external crosslinking agent, and studied the effect of these factors on the pore properties (e.g. specific surface area, micropore surface area and micropore volume) of the resulting hypercrosslinked microporous polymer, and studied the adsorption capacity for gas (CO2, H2 and CH4). PBCA-1 produced from AICI3 catalytic, no crosslinking agent in chloroform solvent has the highest specific surface area (899 m2/g), the adsorption of carbon dioxide at the condition of 1.13 bar/273 K was 4.61 mmol/g. These results suggested that the gas adsorption ability of the hypercrosslinked microporous polymers from the same monomer, while using different methods to prepare is different.(3) Two hypercrosslinked microporous polymers were synthesized by using FeCl3 catalytic friedel-crafts alkylations from two nitrogen-containing monomers. We studied the pore properties (for example, specific surface area, micropore surface area and micropore volume) of this series of polymers, further studied the performance for gas adsorption. In this subject, HCP-2 produced from 4-(diphenylamino) benzaldehyde and indole has the largest specific surface area (1420 m2/g). At the conditions of 1.13 bar/273 K, the CO2 adsorption capacity was 3.58 mmol/g. It is samller than other series in this thesis, but according to the research of the three series, the microporous polymer containing nitrogen has good adsorption properties for carbon dioxide.