Bulk polymerization is a solvent-free process in which the monomer and catalyst are polymerized directly in the absence of a solvent. This method is particularly useful for CO₂based polymerization as it can operate under high-pressure CO₂ conditions, which are often necessary to facilitate CO₂ activation and polymerization. The major advantage of bulk polymerization is its high efficiency, as the absence of a solvent reduces the need for purification steps and increases the yield of the desired polymer. However, this technique can present challenges in terms of heat management and polymerization control, especially when dealing with large volumes or high molecular weight polymers .