Composite Cryogels Based on Hydroxyapatite and Polyvinyl Alcohol and the Study of Physicochemical and Mechanical Properties

Nowadays, due to the increasing number of diseases and injuries related to bone tissue, there is an acute problem of creating a material that could be incorporated into the bone tissue structure and contribute to accelerated bone regeneration. Such materials can be represented by a polymeric matrix that holds the material in the bone and an inorganic component that can be incorporated into the bone structure and promote accelerated bone regeneration. Therefore, in this work we investigated polyvinyl alcohol-based composite cryogels containing an in situ deposited inorganic filler, hydroxyapatite. The freezing temperature was varied during the synthesis process. The composition of the components was determined by infrared spectroscopy and the phase composition by X-ray phase analysis, from which it was found that the main phase of the composite is hydroxyapatite and that the particle size decreases with increasing freezing temperature. The elemental composition of the surface is dominated by carbon, oxygen, phosphorus and calcium; no impurities of other elements not typical for polyvinyl alcohol/ hydroxyapatite cryogels were found. Higher mechanical properties and melting points were observed at -15 °C. Cryogenic treatment parameters did not affect cell viability; however, cell viability was above 80% in all samples.

Impact of Anion Asymmetry on Local Structure and Supercooling Behavior of Water-in-Salt Electrolytes

Salts with asymmetric (fluorosulfonyl)(trifluoromethanesulfonyl)imide (FTFSI) anions have recently been shown to suppress crystallization of water-in-salt electrolytes, enabling low-temperature operation of high-voltage aqueous rechargeable batteries. To clarify the underlying mechanism for the kinetic suppression of crystallization, we investigate the local solution structures and dynamic behaviors of water-in-salt electrolytes based on the asymmetric FTFSI anion and its symmetric anion analogues by Raman spectroscopy and molecular dynamics simulations. We find that monodentate coordination of FTFSI to cations leads to high rotational mobility of the uncoordinated SO₂CF₃ group. We conclude that the peculiar, coordination-dependent, local dynamics in the asymmetric FTFSI anion, manifested by enhanced intramolecular bond rotation, enables the strong supercooling behavior.

A practical guide to the measurement of turbidity curves of cooling crystallisations from solution

Several methods for the determination of the temperatures of crystallisation, crystal proliferation and crystal dissolution in cooling crystallisations are presented and compared.

Nanostructure formation via post growth of particles

Post growth of nanoparticles enables new nanostructure formation and blurs the boundary between crystals and molecules.