Two-dimensional (2D) core–shell nanoparticles
have been
attracting increasing interest due to their wide applications in materials
science. Living crystallization-driven self-assembly (CDSA) is an
ambient temperature, seeded growth method of crystallizable block
copolymers (BCPs) in selective solvents, which has been demonstrated
to be a powerful tool for the creation of one-dimensional (1D)/2D
nanomaterials with precise control over size and compositions. Nevertheless,
the development of an efficient living CDSA approach is a challenge
for the case of semicrystalline poly(p-dioxanone)
(PPDO) as a core-forming block, where the dimensional control is poor.
Herein, we demonstrate that the insufficient size control of 2D PPDO
platelets could be overcome through modulation of solvent compositions
or elevating the crystallization temperatures for PPDO. The possible
mechanism involves an improved unimer solubility that avoids fast
unimer aggregation. As a result, uniform 2D platelet micelles with
a controlled area over a substantial size range are created via epitaxial
growth of the unimer. It is noteworthy that the shape control of 2D
platelet micelles from quasi-square to elongated hexagon to lozenge
shapes can be accessible by regulating the crystallization conditions
such as adding different amounts of cosolvents or crystallization
at an elevated temperature. Meanwhile, spatially defined block comicelles
can be achieved via the seeded growth approach from PPDO core-forming
BCPs with different corona functionalities at elevated temperatures.
The excellent water stability and biocompatibility properties of 2D
PPDO platelet micelles further enable them to have a potential application
as cargo vehicles in the drug delivery field.
Two-dimensional, size-tunable, water-dispersible particle
micelles
with spatially defined chemistries can be obtained by using “living”
crystallization-driven self-assembly (CDSA) approach. Nevertheless,
a major obstacle of crystalline particles in drug delivery application
is the difficulty in accessing to cargo within crystalline cores.
In the present work, we design four different types of biocompatible
two-dimensional platelets with a crystalline poly(ε-caprolactone)
(PCL) core, a hydrophobic poly(4-vinylprydine) (P4VP) segment, and
a water dispersible poly(N,N-dimethyl
acrylamide) (PDMA) block in ethanol by seeded growth method. Transferring
those uniform platelets with tailored compositions to an aqueous solution
in the presence of a hydrophobic drug leads to efficient encapsulation
of the cargo in the P4VP segments via hydrophobic interactions. These
drug-loaded platelets exhibit pH-responsive release behavior in aqueous
media due to the protonated–deprotonated process of P4VP blocks
in acidic and neutral solutions. This work provides initial insight
into biocompatible PCL platelets with low dispersity and precise chemistry
control in stimulus-responsive drug delivery fields.
The prepared hierarchical superhydrophilic membrane exhibited a remarkable antifouling capability owing to dual protection: in situ hydration layer and peripheral turbulent flow.
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