A reliable method to decide whether two polymers A and B are miscible or incompatible would be very helpful in many ways. In this contribution we demonstrate why traditional procedures cannot work. We propose to use the intrinsic viscosities [η] of the polymer blends instead of the composition dependence of the viscosities as a criterion for polymer miscibility. Two macromolecules A and B are miscible because of sufficiently favorable interactions between the two types of polymer segments. For solutions of these polymers in a joint solvent, this Gibbs energetic preference of dissimilar intersegmental contacts should prevail upon dilution and lead to the formation of interpolymer complexes, manifesting themselves in deviations from the additivity of intrinsic viscosities.

Detailed knowledge concerning the phase state (homogeneous or coexistence of two or more condensed phases) of polymer containing mixtures is indispensible in virtually any area related to the production or application of macromolecules. In addition to this qualitative information it is for many purposes highly desirable to dispose of quantitative data regarding solvent quality or, more generally, with respect to the thermodynamic interaction between the components of the mixtures. This contribution starts with a brief presentation of the thermodynamic criteria deciding on the phase state and presents the experimental methods used in this area. The next section gives an overview on typical behaviors of polymer solutions and polymer blends; it is followed by a part recalling widely used theoretical approaches. Finally, a data section collects solvents and non‐solvents for a large number of polymers and presents some examples for the quantitative thermodynamic description of polymer solutions.

Periodontitis is a chronic biofilm-associated inflammatory disease of the tooth-supporting tissues that causes tooth loss. It is strongly associated with anaerobic bacterial colonization and represents a substantial global health burden. Due to a local hypoxic environment, tissue regeneration is impaired. Oxygen therapy has shown promising results as a potential treatment of periodontitis, but so far, local oxygen delivery remains a key technical challenge. An oxygen (O2)-releasing hyaluronic acid (HA)-based dispersion with a controlled oxygen delivery was developed. Cell viability of primary human fibroblasts, osteoblasts, and HUVECs was demonstrated, and biocompatibility was tested using a chorioallantoic membrane assay (CAM assay). Suppression of anaerobic growth of Porphyromonas gingivalis was shown using the broth microdilution assay. In vitro assays showed that the O2-releasing HA was not cytotoxic towards human primary fibroblasts, osteoblasts, and HUVECs. In vivo, angiogenesis was enhanced in a CAM assay, although not to a statistically significant degree. Growth of P. gingivalis was inhibited by CaO2 concentrations higher than 256 mg/L. Taken together, the results of this study demonstrate the biocompatibility and selective antimicrobial activity against P. gingivalis for the developed O2-releasing HA-based dispersion and the potential of O2-releasing biomaterials for periodontal tissue regeneration.

Joint aqueous solutions of branched dextran and linear pullulan are investigated with respect to their phase separation. The experiments demonstrate that the polymers are – depending on the molar mass of dextran – incompatible in aqueous solutions despite their chemical similarity. This finding can be modeled on the basis of an approach accounting for chain connectivity and conformational relaxation of the components. According to these calculations, the polymers exhibit a miscibility gap in joint solutions despite the favorable interactions between them. Using information on the subsystems H2O/dextran and H2O/pullulan, the assumption of complete miscibility of the polysaccharides is required to model the observed phase separation. This analysis predicts the existence of two islands of immiscibility for the ternary system.

Periodontitis is a common global disease caused by bacterial dysbiosis leading to tissue destruction, and it is strongly associated with anaerobic bacterial colonization. Therapeutic strategies such as oxygen therapy have been developed to positively influence the dysbiotic microbiota, and the use of oxygen-releasing substances may offer an added benefit of avoiding systemic effects commonly associated with antibiotics taken orally or hyperbaric oxygen therapy. Therefore, the oxygen release of calcium peroxide (CaO2) was measured using a dissolved oxygen meter, and CaO2 solutions were prepared by dissolving autoclaved CaO2 in sterile filtered and deionized water. The effects of CaO2 on planktonic bacterial growth and metabolic activity, as well as on biofilms of Streptococcus oralis and Porphyromonas gingivalis, were investigated through experiments conducted under anaerobic conditions. The objective of this study was to investigate the potential of CaO2 as an antimicrobial agent for the treatment of periodontitis. Results showed that CaO2 selectively inhibited the growth and viability of P. gingivalis (p < 0.001) but had little effect on S. oralis (p < 0.01), indicating that CaO2 has the potential to selectively affect both planktonic bacteria and mono-species biofilms of P. gingivalis. The results of this study suggest that CaO2 could be a promising antimicrobial agent with selective activity for the treatment of periodontitis.