• Catalyst Selectivity: Another limitation is the selectivity of the catalysts. Catalysts often fail to produce a narrow molecular weight distribution or the desired polymer structure. For example, metal-based catalysts may result in polycarbonates with varying chain lengths and functional groups, reducing the material's consistency and performance. Selectivity issues can also lead to the formation of by-products, which complicate purification and reduce the yield of the desired polymer. Developing catalysts with higher selectivity is essential for enhancing the commercial feasibility of CO₂-based polymers .