Nucleation under Soft
Confinement: Role of Polymer–Solute
Interactions
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Abstract
Nucleation of a crystalline phase almost always occurs
at interfaces.
However, the lack of fundamental understanding of the impact of interfacial
properties on nucleation hinders the design of nucleation active materials
for regulating crystallization in practice. In particular, the role
of intermolecular interactions is often neglected in nucleation under
confinement such as those provided by nano- and microporous materials.
Herein, we report the use of a novel material, polymer microgels with
tunable microstructure and chemistry, for understanding the role of
intermolecular interactions in nucleation under confinement and for
controlling crystallization from solution in general. We demonstrate
that by tuning the polymer–solute interactions, solute nucleation
kinetics were promoted by up to 4 orders of magnitude. Moreover, the
effect of polymer–solute interactions was manifested by the
split of nucleation time scales due to the presence of nucleation
sites of distinct chemical compositions in the microgels, characterized
by small angle neutron scattering. Our mechanistic investigations
suggest that the polymer matrix facilitates nucleation by enhancing
effective solute–solute interactions due to solute adsorptive
partitioning and by promoting molecular alignment inferred from preferred
crystal orientations on polymer surfaces. Our results provide new
insights into nucleation at interfaces and help enable a rational
material design approach for directing nucleation of molecular crystals
from solution