Kinetics of step polymerization with unequal reactivities

Kinetic Modeling and Reactor Simulation and Optimization of Industrially Important Polymerization Processes: a Perspective

The field of what is now referred to as polymer reaction engineering started in the early 1930s with Staudinger’s discovery of macromolecules. Though the earlier work was related primarily to synthesis and kinetics, the field started growing at increasing rates, possibly in the late 1950s or early 1960s. In the early years, this field provided a challenging area of research. It has evolved from the modeling of simple polymerizations to that of more complex systems, to experimentation for filling the gaps in our knowledge, to optimization. This mini-review summarizes a small sampling of the literature in polymerization reaction engineering over the last about four decades using a personal perspective. The concepts in this area are now being applied in a variety of specialized domains, e.g., polymerization at the nano scale, design and control of chain macrostructure and rapid optimal switch-over of grades being manufactured, molecular simulation and computational fluid dynamics, etc.

The effect of limited monomer solubility in heterogeneous step-growth polymerization

Limited monomer solubility imposes very intriguing features on poly(p-phenylenebenzobisoxazole) polymerization. Only one type of functional group is detected at oligomer chain ends, and a high-molecular-weight polymer is obtained even when an excess of the monomer with low solubility is used. These remarkable phenomena are interpreted as an unprecedented "spoon-feeding-of-monomer" mechanism. A novel apparatus for staged polymerization is described that was triggered by the uniqueness of the heterogeneous step-growth polymerization. Hyperbranched polyesters and a polyurethane/polyethylene blend, which represent two phases in the polymerization process, are also discussed.