Hierarchical assemblies of functional polymer particles
are promising
due to their surface as well as physicochemical properties. However,
hierarchical composites are complex and challenging to form due to
the many steps necessary for integrating different components into
one system. Highly structured four-level composite particles were
formed in a four-step process. First of all, gold (Au) nanoparticles,
poly(methyl methacrylate) (PMMA) nanoparticles, and poly(tripropylene
glycol diacrylate) (poly-TPGDA) microparticles were individually synthesized.
By applying microfluidic techniques, polymer nano- and microparticles
were formed with tunable size and surface properties. Afterwards,
the negatively charged gold nanoparticles and PMMA particles functionalized
with a positively charged surface were mixed to form Au/PMMA assemblies.
The Au/PMMA composites were mixed and incubated with poly-TPGDA microparticles
to form ternary Au/PMMA/poly-TPGDA assemblies. For the formation of
composite-containing microparticles, Au/PMMA/poly-TPGDA composites
were dispersed in an aqueous acrylamide–methylenebisacrylamide
solution. Monomer droplets were formed in a co-flow microfluidic device
and photopolymerized by UV light. In this way, hierarchically structured
four-level composites consisting of four different size ranges0.025/0.8/30/1000
μmwere obtained. By functionalizing polymer nano- and
microparticles with different fluorescent dyes, it was possible to
visualize the same composite particle under two different excitation
modes (λex = 395–440 and λex = 510–560 nm). The Au/PMMA/poly-TPGDA composite-embedded
polyacrylamide microparticles can be potentially used as a model for
the creation of composite particles for sensing, catalysis, multilabeling,
and biomedical applications.
Polyethersulfone (PES) is a widely used polymer in consumer and technical products. An important application is PES membranes used in the biopharmaceutical industry for sterilizing‐grade filtration and for filtration of food and beverages. For both uses, detailed information about migrating compounds that can be extracted from the polymeric material into a liquid must be gathered. In the pharmaceutical industry, comprehensive extractables studies are required for contact materials, and the data is used in the qualification of the process equipment. PES is generated via polycondensation, which forms cyclic oligomers as a by‐product of the reaction. However, no structural information is available for these cyclic oligomers so far. In this publication, we present the analytical determination of PES cyclic oligomers. Their presence in extracts of PES membrane filters is confirmed. The structure of the PES cyclic trimer is elucidated by X‐ray and NMR investigation, obtained as crystals from the sublimation of the PES raw material. A strategy is shown to assess the toxicity of such cyclic oligomers and to derive a permitted daily exposure (PDE). The data will reduce the levels of unknowns in extractables and leachables screenings and supports the risk assessment of PES sterile filters.
The 2,5-substituted 4-hydroxythiazoles form a fluorescent dye class with wide-range-tunable absorption and emission wavelengths. The insights gained on these heterocyclic fluorescence systems are intended to contribute to the development of alternative applications of such molecules in the various areas of biology, chemistry and technology. Therefore, a synthesis strategy for the bromination of the thiazole core was developed, which allows the implementation of various cross-coupling reactions on thiazoles. Furthermore, the so formed conjugated cross-coupling products are highly fluorescent and were investigated in terms of their spectroscopic properties.
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