A Continuous Flow Based Irreversible Polycondensation Enables Synthesis of Polycarbonate Diols Beyond Batch Limitations

Aliphatic polycarbonate polyols have emerged as valued precursors for high-performance polyurethanes due to their superior hydrolytic and thermal stability. These polyols are industrially produced using conventional batch reactors which suffer from the limited control over polycondensation and low efficiency of production. In this work we report a continuous-flow platform for the continuous production of polycarbonate diols. This process is based on the irreversible polycondensation of short-chain diols with diphenyl carbonate in the presence of methanesulfonic acid catalyst. This system enables quasi-first-order kinetics with high yield in short residence time, affording polycarbonate diols with molecular weights ranging from M_n = 1200–2600 g·mol^-1 and dispersities of 1.9 - 2.3. We extend the continuous process for the production of polyurethanes by utilizing the crude polycarbonate diols directly for polyurethane synthesis, enabling an integrated and purification-free process. This work establishes a unified flow platform for the continuous production of step-growth polymers with high precision providing a promising solution to the longstanding limitations of batch production.