Chemical reactions are often carried out under mixing, especially at an industrial scale. Mixing aims to homogenize the concentrations and temperatures of reactants over a whole reactor, and therefore often requires a 3D flow and sometimes a 2D flow. This mixing-driven-chemistry ignores or does not have to consider the effects of flow/mixing on reaction kinetics and/or selectivity because flow/mixing is likely not strong enough to significantly drive molecules from their equilibrium conformations to non-equilibrium ones. This article proposes flow-driven-chemistry which aims at manipulating the dynamics and structural order of molecules (conformation, alignment, diffusion and collision) through a strong 1D flow in order to tune the reaction kinetics and/selectivity. It describes the scientific and technical bases of flow-driven chemistry as well as its scientific and technical challenges. It provides the state of the art of the understanding related to flow-driven chemistry and perspectives for future developments.
Reactive polymer blending is basically a flow/mixing-driven process of interfacial generation, interfacial reaction for copolymer formation and morphology development. This work shows two antagonistic effects of mixing on this process: while mixing promotes copolymer formation by creating interfaces and enhancing collisions between reactive groups at the interfaces, excessive mixing may pull the in-situ formed copolymer out of the interfaces to one of the two polymer components of the blend, especially when the copolymer becomes highly asymmetrical. As such, the copolymer may loss its compatibilization efficiency. The mixing-driven copolymer pull-out from the interfaces is a catastrophic process (less than a minute), despite the high viscosity of the polymer blend. It depends on the molecular architecture of the reactive compatibilizer, polymer blend composition, mixing intensity and annealing. These findings are obtained using the concept of reactive tracer-compatibilizer and a model reactive polymer blend.