The Synthesis Of Imidazole Functionalized Mesoporous Polymer And Its Application In The Field Of Carbon Dioxide Conversion

Mesoporous polymers have attracted much attention due to their unique pore structures and pure organic frameworks.The organic frameworks could easily be chemically modified,forming mesoporous organic polymers with particular functions.The imidazole groups,involving in various chemical reactions,are of vital importance in the chemical synthesis.And thus,preparation of imidazole-functionalized mesoporous polymers is of great potential uses both academically and industrially.In this dissertation,we focused on the preparation of imidazole-functionalized mesoporous polymers and the use of the obtained imidazole-functionalized mesoporous polymers in the cycloaddition reactions of carbon dioxide.The background and the main work of this dissertation are as follows.We have prepared imidazole-functionalized mesoporous polymers(4-IP-MPs)by using 4-(1H-imidazol-l-yl)phenol(4-IP)as the imidazole source in our previous work.However,the 4-IP-MPs are not so stable because only the ortho-position of 4-IP could react with formaldehyde during polymerization and no cross-linked structure could be obtained.3-(1 H-imidazol-1-yl)phenol(3-IP),possessing phenolic hydroxyl and imidazole ring in the meta position,might be helpful in the formation of cross-linked imidazole-functionalized mesoporous polymers(3-IP-MPs).Furthermore,the neighboring benzene ring might have an effect on the performance of imidazole ring due to the conjugation effect.To reduce the conjugation effect,a non-conjugated imidazole-functionalized mesoporous polymer was prepared by introducing a methylene group between the benzene ring and the imidazole ring.Based on this,this dissertation was divided into two parts.In the second chapter,mesoporous polymer 3-IP-MPs' were prepared using the imidazole-functionalized precursor as the imidazole source which was obtained directly by 3-IP,phenol and formaldehyde in alkaline condition and F127 as the template through the solvent evaporation induced self-assembly method.The structure of the obtained imidazole-functionalized mesoporous polymers was confirmed using the X-ray diffraction and the N2 adsorption-desorption.The influence of the pre-polymerization time,the amount of 3-IP and the relative position of the imidazole ring and the phenolic hydroxyl on the pore structure was systematically investigated.All characterizations confirmed the presence of the imidazole group in the obtained mesoporous polymers and the imidazole-functionalized mesoporous polymers are stable up to 420 ?.The catalytic performance of the prepared was evaluated using the cycloaddition reaction of carbon dioxide and epoxide.Compared with the 4-IP-MPs,the 3-IP-MPs prepared herein exhibited more stable activity in the cycloaddition reaction and no obvious activity decrease could be observed after reuse for three cycles.In the third chapter,3-((1-hydrogen-imidazole-1-yl)methyl)phenol(3-IMP)was firstly prepared by introducing a methylene between imidazole and benzene.Using the prepared(3-IMP)as the imidazole source,we investigated the preparation of non-conjugated imidazole-functionalized mesoporous polymer(3-IMP-MPs).Highly order mesoporous 3-IMP-MPs could be easily prepared when the amount of the 3-IMP was 5%,with BET surface area and pore volume of 408 m2/g and 0.52 cm3/g,respectively.Systematical characterizations proved the presence of imidazole group in the obtained 3-IMP-MPs and the 3-IMP-MPs are highly stable.The prepared 3-IMP-MPs were used as catalyst for cycloaddition reaction of carbon dioxide and epoxide.The reaction conditions and the substrates were thoroughly investigated.The 3-IMP-MPs exhibited excellent cycle stability,with no obvious decrease in conversion after five cycles.