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Degree of polymerization; Dissipative particle dynamics; Dissipative particle dynamics simulation; Interfacial polymerization; Membrane preparation; Polymer characteristics; Reactive extrusions; Step-growth polymerizations
Abstract:
Step-growth alternating interfacial polymerization between two miscible
or immiscible monomer melts is investigated theoretically and by
dissipative particle dynamics simulations. In both cases the kinetics
for an initially bilayer system passes from the reaction to diffusion
control. The polymer composed of immiscible monomers precipitates at the
interface forming a film of nearly uniform density. It is demonstrated
that the reaction proceeds in a narrow zone, which expands much slower
than the whole film, so that newly formed polymer is extruded from the
reaction zone. This concept of ldquoreactive extrusionrdquo is used to
analytically predict the degree of polymerization and distribution of
all components (monomers, polymer, and end groups) within the film in
close agreement with the simulations. Increasing the comonomer
incompatibility leads to thinner and more uniform films with the higher
average degree of polymerization. The final product is considerably more
polydisperse than expected for the homogeneous step-growth
polymerization. The results extend the previous theoretical reports on
interfacial polymerization and provide new insights into the internal
film structure and polymer characteristics, which are important for
membrane preparation, microencapsulation, and 3D printing technologies.
A systematic way of mapping the simulation data onto laboratory scales
is discussed.
