Different methods on controlling ZIF particle size during synthesis have been reported previously. Tanaka et al. reported a method on controlling ZIF-8 particle size in aqueous solution at room temperature. Different 2-methylimidazole/zinc (MeIm/Zn) ratios ranging from 4 to 100 were utilized whilst keeping the water and zinc concentration constant 1. SEM analysis of the products from different MeIm/Zn ratio showed that the particle diameter was inversely proportional to MeIm/Zn ratio as reported in (Table 1.1). By increasing the concentration of the linker (2-methylimidazole), increases the concentration of free imidazolate ions which increases the nuclei for complex formation, leading to smaller particles.
Table 2.1: Different MeIm/Zn ratio with the resulted ZIF-8 particle diameter.
MeIm/Zn ratio Particle diameter (?m)
Tsai et al. reported synthesis of ZIF-8 nanoparticles with particle size control by temperature utilizing isothermal benchtop reaction in methanol. As the temperature was increased from -15 to 60 °C, the average particle sizes decreased from 78 to 26 nm. Moreover, Pan et al. successfully controlled the particle size of ZIF-8 particles utilizing surfactants as capping agents to control the particle size during synthesis 2. By increasing the wt % of surfactant cetyltrimethylammonium