Dialysis diffusion kinetics are performed via in-situ NMR spectroscopy for numerous different raw polymeric solutions to result in a general guideline for polymer purification using dialysis. In several approaches, a...
In this work, the synthesis and characterization of a compact, ferrocene tetramer and a linear viologen polymer is reported. The latter material is a new, 4,4′-bipyridine containing, organo-soluble polymer. As aimed for solubility in nonpolar solvents, a 2-ethylhexyl-moiety to promote organosolubility and 4-vinylbenzyl serving as a polymerizable group are introduced to a 4,4′-bipyridine. The halide anions of the monomer cation are exchanged to bis(trifluoromethansulfon)imide, which further enhances organosolubility. The monomer is subsequently copolymerized with styrene by free radical polymerization. In addition, a four-ferrocene-containing compact structure, based on pentaerythritol, is synthesized via the straightforward radical thiol-ene reaction. The polymer solutions are thoroughly characterized hydrodynamically. Subsequently, propylene carbonate-based solutions of both materials are prepared to allow an assessment for future energy storage applications. This is done by testing battery characteristics in a custom-made flow-cell with a simple dialysis membrane for physical separation of the active materials. The capability of energy storage is verified by leaving the charged materials in solution in an open circuit for 24 h. Here, more than 99% of the stored charges can be recovered. Cycling the battery for 100 times reveals the remarkable stability of the materials of only 0.2% capacity loss per day in the battery setup.
All-aqueous, surfactant-free, and pH-driven nanoformulation methods to generate pH-and temperature-responsive polymer nanoparticles (NPs) are described. Copolymers comprising a poly(methyl methacrylate) (PMMA) backbone with a few units of 2-(dimethylamino)ethyl methacrylate (DMAEMA) are solubilized in acidic buffer (pH 2.0) to produce pH-sensitive NPs. Copolymers of different molar mass (2.3-11.5 kg mol −1 ) and DMAEMA composition (7.3-14.2 mol%) are evaluated using a "conventional" pH-driven nanoformulation method (i.e., adding an aqueous polymer solution (acidic buffer) into an aqueous non-solvent (basic buffer)) and a robotized method for pH adjustment of polymer dispersions. Dynamic light scattering, zeta-potential (𝜻), and sedimentation-diffusion analyses suggest the formation of dual-responsive NPs of tunable size (from 20 to 110 nm) being stable for at least 28 days in the pH and temperature intervals from 2.0 to 6.0 and 25 to 50 °C, respectively. Ultraviolet-visible spectroscopic experiments show that these NPs can act as nanocarriers for the pH-sensitive dipyridamole drug, expanding its bioavailability and potential controlled release as a function of pH and temperature. These approaches offer alternative strategies to prepare stimuli-responsive NPs, avoiding the use of harmful solvents and complex purification steps, and improving the availability of biocompatible polymer nanoformulations for specific controlled release of pH-sensitive cargos.
A concise
synthesis
for the monomer 2-ferrocenylethyl methacrylate
is presented. This versatile monomer can be homopolymerized to yield
highly lipophilic, stimuli-responsive homopolymers and can also be
used to further synthesize water-soluble copolymers. For the first
time, the X-ray crystal structure of this monomer is shown. The copolymerization
with two different ionic monomers was thoroughly investigated at various
temperatures. Electrochemical investigations were performed with a
well-established viologen to assess the viability of the new material
for possible energy storage scenarios. Charge storage experiments
at ambient and elevated temperature point toward a satisfying stability
of the new materials, with charge recoveries of approximately 95%.
The Coulombic efficiency of the materials was determined via galvanostatic
cycling and was found to be above 99%, which is comparable to other
suitable redox-active polymers for charge storage studies.
Miktoarm star polymers are a particular type of branched polymers featuring a star-shaped architecture with arms based on different polymer types. Such materials exhibit unique thermal, mechanical, and selfassembly properties. Hence, this polymer class is of great interest in different research fields. So far, the synthesis of these entities can be rather challenging, particularly applying covalent strategies for linking of the different polymers. Thus, an approach for the synthesis of such polymer architectures is presented using orthogonal metal−ligand interactions to connect the different building blocks, resulting in a miktoarm topology. The obtained structures are investigated via diffusion-ordered nuclear magnetic resonance spectroscopy, by analytical ultracentrifugation and dynamic light scattering.
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