Optimization of Cu-Integrated Covalent Organic Frameworks via Design of Experiments

The formation of covalent organic frameworks (COFs) on copper (Cu) surfaces requires effective linking materials to bridge the two interfaces. In this study, amine (-NH₂) functionalization of Cu particles was optimized using a full factorial experimental design with ethylenediamine (EDA) and ethanol (EtOH) as precursors. Elemental analysis quantified the amine groups formed, revealing that EDA had a more significant effect than EtOH, with minimal interaction between them. Optimization using a response optimizer predicted a maximum NH₂ molar ratio of 13.4 under 15 (mol/Cu-mol) of EDA and 100 (mol/Cu-mol) of EtOH. Further factorial design optimization of synthesis temperature and reaction time identified ideal conditions of 100 °C and 12 h. Subsequently, Cu-COF synthesis was optimized using a mixture design methodology. Statistical analysis, including ANOVA and regression modeling, confirmed the robustness of the experimental model, yielding an R² value of 0.996. The optimal molar precursor ratios for Cu/COF synthesis were determined, predicting a maximum COF yield of 7.3 mol/Cu-mol. Process optimization further refined synthesis parameters, identifying ideal conditions, 180 °C reaction temperature, 18 h reaction time, and 800 rpm stirring speed, to achieve a COF yield of 7.5 mol/Cu-mol.