Cations are crucial components in emerging functional
polyelectrolytes
for a myriad of applications. Rapid development in this area necessitates
the exploration of new cations with advanced properties. Herein we
describe a combination of computational and experimental design of
cobaltocene metallo-cations that have distinct electronic and redox
properties. One of the direct outcomes on the first synthesis of a
complete set of cation derivatives is to discover highly stable cations,
which are further integrated to construct metallo-polyelectrolytes
as anion-exchange membranes in solid-state alkaline fuel cells. The
device performance of these polyelectrolytes under highly basic and
oxidative environments is competitive with many organo-polyelectrolytes.
Polymerization-induced self-assembly (PISA) and crystallization-driven self-assembly (CDSA) are among the most prevailing methods for block copolymer self-assembly. Taking the merits of scalability of PISA and dimension control of CDSA, we report one-pot synchronous PISA and CDSA via ring-opening metathesis polymerization (ROMP) to prepare nano-objects based on a crystalline poly(ruthenocene) motif. We denote this self-assembly methodology as ROMPI-CDSA to enable a simple, yet robust approach for the preparation of functional nanomaterials.
Results and discussionThe synchronous process of PI-CDSA requires the incipient production of a corona-forming block that is carried out under living polymerization in a good solvent medium. The same solvent system becomes non-selective for the second coreforming block as the degree of polymerization (DP) of the second segment proceeds to a threshold that induces crystallization. 22
New antimicrobial agents are needed
to address ever-increasing
antimicrobial resistance and a growing epidemic of infections caused
by multidrug resistant pathogens. We design nanostructured antimicrobial
copolymers containing multicyclic natural products that bear facial
amphiphilicity. Bile acid based macromolecular architectures of these
nanostructures can interact preferentially with bacterial membranes.
Incorporation of polyethylene glycol into the copolymers not only
improved the colloidal stability of nanostructures but also increased
the biocompatibility. This study investigated the effects of facial
amphiphilicity, polymer architectures, and self-assembled nanostructures
on antimicrobial activity. Advanced nanostructures such as spheres,
vesicles, and rod-shaped aggregates are formed in water from the facial
amphiphilic cationic copolymers via supramolecular interactions. These
aggregates were particularly interactive toward Gram-positive and
Gram-negative bacterial cell membranes and showed low hemolysis against
mammalian cells.
We report crystallization-driven self-assembly (CDSA) of metallo-polyelectrolyte block copolymers that contain cationic polycobaltocenium in the corona-forming block and crystallizable polycaprolactone (PCL) as the coreforming block. Dictated by electrostatic interactions originating from the cationic metalloblock and crystallization of the PCL, these amphiphilic block copolymers selfassembled into two dimensional platelet nanostructures in polar protic solvents. The 2D morphologies can be varied from elongated hexagons to diamonds, and their stability to fragmentation was found to be dependent on the ionic strength of the solution.
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