Unlike many other products from the chemical industries, polymer molecules cannot easily be separated from each other. Therefore, the material has to be produced with the required specification at the reactor stage. The correct choice of reaction model is crucial for the prediction of reactor behavior. Allowance must be made for the effects of high viscosities on both heat transfer and reaction kinetics, In suspension polymerization, drop sizes, drop mixing, and sedimentation all require particular attention. With emulsion polymerization, a change in the reactor start-up procedure can lead to changes in dynamic behavior, monomer conversion, and product quality. If we can learn from nature, polymerization reactors may take new farms in the future.