Synthesis and characterization of ZIF-8 and ZIF-8/polymer composites

Milburn, Kate
Synthesis and characterization of ZIF-8 and ZIF-8/polymer composites. Master of Philosophy thesis, University of Liverpool.

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In this project we carried out a systematic study into the synthesis of ZIF-8 using different experimental conditions to find the most suitable ZIF-8 particle morphologies. We then investigated the preparation of aligned porous ZIF-8-polymer composites via the freeze drying method. For the purposes of our project, we decided that particles between 100nm and 2um would be a suitable size for the preparation of polymer composite materials. And smaller would lead to the particles not being visible in the polymer framework and any larger they would be difficult to disperse homogenously throughout the framework. We used several different methods from literature, finally focusing on a method that was used by Cravillon which used an auxiliary ligand to modulate their reaction. The two auxiliary ligands were sodium formate and 1-methyl imidazole. We used water as the solvent to prepare these size-controllable ZIF-8 particles. This was carried out in a much lower volume of solvent than the corresponding methanol reactions. We carried out a systematic study into a wide range of conditions wrt 2-MeIM and 1-MeIM concentration as well as temperature- using room temperature, heating the reaction and solvothermal conditions. Three ZIF-8 conditions were identified as being promising for taking forward and these were all in water 1:20:20 Zn:2-MeIM:1-MeIM RT ~350nm, 1:10:2 80C ~400nm and 1:3:1 80C ~2.5um. The 1:3:1 had a very low conc of 2-MeIM and formed interesting nano-aggregate particles. We then investigated the preparation of aligned porous ZIF-8-polymer composites via the freeze drying method. These three particles were used to prepare aligned porous ZIF-8@PSS composite materials with three different ratio’s of ZIF:PSS 1:1, 1:3, and 3:1. These were directionally frozen in liquid nitrogen slowly ~1mm/10 seconds and then placed in a freeze drier to sublime the solvent and leave the porous structure intact. These structures were all successful and we characterised the two most successful, 1:2:20 and 1:10:2 for the BET surface area, pore size and volume and BJH average pore size. For 1:20:20 RT 3:1 ZIF-8:PSS we found a BET surface area of 440m squred per gram. This reduced as the ratio of zif:pss decreased as expected. The 1:10:2 case had a larger surface area of 521 m squared per gram. These two composite structures were aligned porous frameworks with high surface areas and tunable particle sizes. The next steps would be to test them for the applications.

Item Type: Thesis (Master of Philosophy)
Additional Information: Date: 2014-10 (completed)
Depositing User: Symplectic Admin
Date Deposited: 05 Feb 2015 13:52
Last Modified: 17 Dec 2022 01:30
DOI: 10.17638/02006519