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Polycarbonate-urethane-co-silicone (PCU-Sil) are gaining increasing interest in biomedical application, such as drug delivery systems, coatings and combination products, due to their adjustable mechanical properties. They can be easily processed using a wide range of methods. Biocompatibility can be improved by surface modifications, such as coupling drugs, proteins, antibodies or polymer layers, which extends the range of biomedical applications. To generate additional coupling, the first step would be the generation of functional groups on the polymer surface using surface activations, such as plasma activation. In this context, the assignment of the functional groups is important, which can be done by XPS measurements. Within this study the analysis of the generated functional groups after oxygen (O2) plasma activation of two PCU-Sils was performed. In addition, the stability of the generated surface modification was evaluated after 24 hours. It was surprising that the generated groups were differently stable and also different groups were generated or rearranged over time, which would not have been recognizable if only contact angle measurements were used.

For the use of polymers as biomaterials in the production of implants, several processing methods are needed. Besides injection molding or Fused Deposition Modeling as temperature based processes, also solvent based processes were performed such as solvent-casting and electrospinning. As fabrication of medical devices makes use of potentially hazardous or toxic solvents, they have to be extracted from the final medical device. For analyses of residual solvents different methods can be used e.g. gas chromatography (GC), coulometric elemental analysis or thermogravimetrical analyses (TGA). Here we present first results for the use of X-ray photoelectron spectroscopy (XPS) to yield elemental as well as spatial information on residual solvents in polymeric materials. Therefore we analysed PLLA as biodegradable electrospun polymer, TPC-ET as biostable polymer and a PLLA-iron composite as example of a polymer metal composite via XPS and etching processes. It was possible to determine residual halogen containing solvents in all tested polymers processed from polymeric solution. As discrimination between polymer and solvent was made possible by specific elements, XPS measurements may be a suitable tool to identify even small amounts of solvent. Thus XPS analyses will help to optimize polymer processing in order to remove residual solvents.

For the development of combination products, the determination of the release kinetics of polymer-based drug delivery systems (DDS) is a central and often timeconsuming investigation. Classical methods are often unsuitable for large-scale screening of potential polymers for combination products. We present a rapid method based on surface plasmon resonance spectroscopy (SPR), using PEGDA700 (Poly(ethylene glycol) diacrylate, average molecular weight (Mn) 700) as an example. This method is capable of determinating the kinetics of drug association and subsequent release within minutes. The proportion of desorption and diffusion can be determined separately. Surface plasmon resonance spectroscopy (SPR) is a label-free and very sensitive optical technique, which allows for real-time observation of surface interactions. The prepared SPR chips were spin-coated with PEGDA700 and crosslinked via photoinduced polymerization. The association and dissociation kinetics of dexamethasone phosphate in swollen PEGDA700 have been studied at different concentrations. The maximum loading of the surface was also obtained by this method. The study of PEGDA presented here identified the wellestablished SPR-based spectroscopy as a potential tool in the development of combination products.

The preparative assembly and electrochemical and photophysical behavior of di- and tetranuclear complexes held together by minimalist ditopic ligands based on 1-phosphine- or 1-pyridine-substituted prop-1-ynes are presented.

Alkyne complexes with vicinal substitution by a Lewis acid and a Lewis base at the coordinated alkyne are prospective frustrated Lewis pairs exhibiting a particular mutual distance and, hence, a specific activation potential. In this contribution, investigations on the generation of a WII alkyne complex bearing a phosphine as Lewis base and a carbenium group as Lewis acid are presented. Independently on potential substrates added, an intramolecular cyclisation product was always isolated. A subsequent deprotonation step led to an unprecedented side‐on λ5‐phosphinyne complex, which is interpreted as highly zwitterionic according to visible absorption spectroscopy supported by TD‐DFT. Low‐temperature 31P NMR and EPR spectroscopic measurements combined with time‐dependent IR‐spectroscopic monitoring provided insights in the mechanism of the cyclisation reaction. Decomposition of the multicomponent IR spectra by multivariate curve resolution and a kinetic hard‐modelling approach allowed the derivation of kinetic parameters. Assignment of the individual IR spectra to potential intermediates was provided by DFT calculations., A sought‐after combination of a phosphine as Lewis base and a carbenium centre as Lewis acid at a WII alkyne complex turned out to be stable as a diradical. Intramolecular cyclisation and subsequent deprotonation provided a side‐on complex of a λ5‐1‐phospha‐2,3‐didehydrofluoranthene, which can be denoted as λ5‐phosphinyne.