Complex coacervated-based assemblies
form when two oppositely charged
polyelectrolytes combine to phase separate into a supramolecular architecture.
These architectures range from complex coacervate droplets, spherical
and worm-like micelles, to vesicles. These assemblies are widely applied,
for example, in the food industry, and as underwater or medical adhesives,
but they can also serve as a great model for biological assemblies.
Indeed, biology relies on complex coacervation to form so-called membraneless
organelles, dynamic and transient droplets formed by the coacervation
of nucleic acids and proteins. To regulate their function, membraneless
organelles are dynamically maintained by chemical reaction cycles,
including phosphorylation and dephosphorylation, but exact mechanisms
remain elusive. Recently, some model systems also regulated by chemical
reaction cycles have been introduced, but how to design such systems
and how molecular design affects their properties is unclear. In this
work, we test a series of cationic peptides for their chemically fueled
coacervation, and we test how their design can affect the dynamics
of assembly and disassembly of the emerging structures. We combine
them with both homo- and block copolymers and study the morphologies
of the assemblies, including morphological transitions that are driven
by the chemical reaction cycle. We deduce heuristic design rules that
can be applied to other chemically regulated systems. These rules
will help develop membraneless organelle model systems and lead to
exciting new applications of complex coacervate-based examples like
temporary adhesives.
Sustainable thermoplastic elastomers derived from block copolymers of syndiotactic poly(3-hydroxybutyrate) and poly((−)-menthide) were synthesized via yttrium-mediated ring-opening polymerization.
The
polymer class of poly(vinylphosphonates) offers a wide array
of attractive features such as high biocompatibility, thermoresponsive
behavior, and the option for the directed introduction of small molecules
at the initial step of the polymerization. Through the latter, polymer
conjugates consisting of targeting ligands, fluorophores, or pharmacologically
active substances become feasible. However, the modification of such
compounds for the utilization in postpolymerization functionalization
is usually cumbersome due to their structural complexity. In this
study, we considered this factor and envisioned a flexible platform
of functional polymers via the introduction of initiators comprising
reactive functionalities. Hence, a series of customized initiators
with protected functional groups (O-tert-butyldimethylsilyl,
2,5-dimethylpyrrole, and STrityl) were synthesized and studied in
the C–H bond activation with Cp2Y(CH2TMS)(THF). The positive outcome of the activation experiments allowed
the use of these initiators in the rare earth metal-mediated group
transfer polymerization (REM-GTP). The versatility of this approach
was demonstrated by end-group analysis using electrospray ionization
mass spectrometry (ESI-MS) and DOSY-NMR, confirming the incorporation
of the individual end group in poly(diethyl vinylphosphonate) (PDEVP).
On this basis, PDEVP with varying feed concentrations was generated
and the protection groups were removed to release the reactive motif.
Doing so eventually enabled the successful coupling of model compounds,
namely, cholesteryl chloroformate and N-phenyl maleimide,
which established a foundation in the direction of more sophisticated
polymer conjugates involving complex and highly functional compounds.
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