Polymerization kinetics under confinement

Abstract

The kinetics of polymerization under confinement is considered. Experimental results show that the polymerization kinetics inside a core–shell electrospun nanofiber differs from that in the bulk (inside a thick film). The observed phenomena can be described in the framework of polychromatic kinetics. In order to explain the chemical reaction mechanism, the spatial features of the process in question, namely the cluster structure forming during the system polymerization, are to be taken into account. The key point of the proposed mechanism is as follows: when the mean size of the clusters becomes comparable with the internal fiber diameter, the rate of reaction will decrease. This decrease is due to two reasons. Firstly, the presence of a boundary obstructs the cluster growth due to steric restrictions; and secondly, the formed clusters separate the reacting area into several isolated regions, in which fluctuations in catalyst concentration are observed without their diffusive dissipation. As a result the polymerization reaction becomes a polychromatic one, where the rate of reaction is decreasing with time.