Structure and bioactivity studies of new polysiloxane-derived materials for orthopedic applications

Development of multiphase bioceramics from a filler-containing preceramic polymer

“…The formation of di-and tri-calcium silicates is thus the result of local over-concentration of calcium oxide (di-and tricalcium silicates in fact correspond to a CaO/SiO 2 molar ratio far exceeding 1). The formation of secondary silicates is confirmed by the findings of Paluszkievicz et al [25] even if the quantitative details of the phase assemblage of their samples were not reported. A further corroboration of our hypothesis concerning the behaviour of the system with CaCO 3 is given by the results obtained with Ca-acetate aqueous solution, when used without any surfactant added to the silicone solution.…”

“…In addition to that, the amorphous SiOC matrix embedding the crystalline phases has recently been found to exhibit an anti-trombogenic behaviour similar to that of pyrolytic carbon [38]. Thus, the similar materials obtained by Paluszkievicz et al [25] which featured the additional presence of cristobalite phase and were found to show bioactivity when immersed in simulated body fluid, constitute indeed an important reference.…”

“…Due to the difficulties in sintering, wollastonite is generally obtained by complex techniques (such as devitrification of glass [20,21], sol-gel processing [22], spark plasma-sintering [14][15][16][17], solution combustion processes [23] etc.). The formation of calcium silicates, not intended for biological applications, from silicones filled with CaO precursors was pioneered by Russian researchers in 1980s [24]; a more recent work, specifically dedicated to medical applications, was carried by Paluszkievicz et al [25], who investigated a polymethylphenylsiloxane, filled with Ca(OH) 2 , CaCO 3 , Na 2 HPO 4 micro-powders and silica nano-powders (of about 100 nm). The present approach is based on the reaction of the silica deriving from the pyrolysis of a polymethylsiloxane with several precursors of calcium oxide (calcium carbonate micro-powders, calcium acetate in aqueous solution, calcium oxide nano-powders) and expands what reported in [26].…”

The study on the phosphate glass melted by microwave irradiation

“…In the spectra presented in Fig. 3, the characteristic mode of raw mixtures at $3500 cm À1 is due to the stretching vibration of OH group connected with the presence of Ca(OH) 2 [17]; simultaneously, the intensity of polar hydroxyl peak increases after adding water into raw mixture. Cheshkova and Stoilova reported that OH groups (3570-3500 cm À1 ) perturbed through their oxygen atoms due to formation of ammonia [18].…”

Alkali activation of a novel calcium‐silicate hydraulic binder with CaO/SiO2 = 1.1

“…However, in the sample activated with Na 2 CO 3 , some features assigned to the presence of were also present, that is, the signals at 1420 and 875 cm −1 attributed to asymmetric stretching (ν 3 []) and in‐plane bending (ν 2 []) vibration modes, respectively. In addition, the in‐plane bending mode (ν 4 []) was present at ~712 cm −1 ; however, it partially overlapped with the feature at 719 cm −1 , caused by the bridging Si‐O‐Si stretching vibrations of its 3‐membered ring structures, that is, related to the presence of pseudowollastonite. In addition to the feature at 719 cm −1 , pseudowollastonite also presented a signal at 985 cm −1 , corresponding to the stretching vibration mode of non‐bridging Si‐O − , which is more evident in the anhydrous sample and decreases after hydration.…”