XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
194
T1: P–61
Effect of heat treatment on the structure of gel derived material from
the SiO
2
-Al
2
O
3
system
Katarzyna Cholewa-Kowlaska
1
, Michal Dziadek
1
, Barbara Zagrajczuk
1
,
Klaudia Chciuk
1
, and Maria Łączka
1
1
AGH University of Science and Technology, Faculty of Materials Science and Ceramics,
Department of Glass Technology and Amorphous Coatings, 30 Mickiewicza Av., 30-059 Krakow,
e-mail: cholewa@agh.edu.pl
The structure of non-crystalline aluminium silicate glasses has been a point of interest for many
years. As the glass forming ability of silica melts with considerable amounts of alumina is low,
special preparation methods should be used in order to supress crystallization i.e. ultra-rapid
quenching of the melt, CVD process.
One of the most suitable method for obtaining glasses from the Al
2
O
3
–SiO
2
system is the sol-gel
process, however several chemical routes are available for preparing chemically homogeneous gels.
In the present study tetraethoxysilane Si(OC
2
H
5
)
4
(TEOS), aluminium tri-sec-butylate (TBA)
Al(OCH[CH
3
]C
2
H
5
)
3
, and aluminium chloride AlCl
3
·6H
2
O were used as the precursors for SiO
2
and
Al
2
O
3
respectively. The reactions were provided in water based solution at the presence HCl as the
hydrolysis and condensation catalyst. Several composition xSiO
2
–(100–x)Al
2
O
3
were synthetized
were x=100, 90, 80, 50 mol%. After gelation the gels were subjected to thermal treatment at the
temperatures 500–900°C and next their phase composition and structure were investigated. We have
used FTIR spectroscopy, XRD analysis as well as
27
Al,
29
Si MAS NMR to investigate the local
structures about Si and A1. Phase analysis reveals that materials with high silica content after heating
at different temperatures remain amorphous, while with the increase of Al
2
O
3
concentration the
beginning of crystallization γ-Al
2
O
3
was observed. The FTIR spectra of obtained glasses show three
main absorption bands at around 460, 805 cm
−1
range and 1100 cm
−1
correspond to bending
vibrations of O–Si–O and stretching of Si–O–Si bonds. Additional shoulder observed around 1220
cm
−1
can be ascribed to the longitudinal optical Si–O–Si asymmetric stretching vibrations. There are
also observed band characteristic for Al in octahedral and tetrahedral coordination in the range 600–
800 cm
−1
and 1370 cm
−1
[1]. The new bands appeared after thermal treatment at temperatures 700–
900°C are related to the γ-Al
2
O
3
. Analysis of
29
Si MAS NMR of the materials with Al
2
O
3
≤ 20 mol%
suggest the presence only Q4 species, while in glasses with the 50 mol% Al
2
O
3
concentration Q3
entities are observed. One central problem has been the nature of the aluminum coordination in these
glasses. Interestingly in the
27
Al MAS NMR spectra of all materials three resonances at 0, 30, 55 ppm
are present characteristic for octahedral, pentahedral and tetrahedral coordination of Al, respectively
[2]. The most intense resonance for Al in CN
5
is observed for 50 mol% SiO
2
– 50 mol% Al
2
O
3
glass.
Evaluation of the heat treatment influence on the phase composition and structure is an important
aspect in the investigation on gel-derived materials Research conducted on the influence of different
types of heat treatments on the gel-derived materials from the SiO
2
-Al
2
O
3
enables us their full and
detailed characterization and facilitate a further designing of similar materials with the requested
properties.
Keywords: alumino-silicate glasses; FTIR; NMR spectroscopy
Acknowledgments
This work was supported by the National Science Centre, Poland (2014/13/B/ST8/02973) and Polish
Ministry for Science and Higher Education, AGH University of Science and Technology, Faculty of
Materials Science and Ceramics (11.11.160.365).
References
[1] M. Schmucker at al.. J. Non-Crystal. Sol. 217 (1997) 99.
[2] R.K. Sato, P.F. McMillan, J. Phys. Chem. 95 (1991) 4483.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
195
T1: P–62
FTIR, Raman and XRD investigations of CuO-doped silicate bioactive
glasses with potential angiogenic activity
Michal Dziadek
1
, Barbara Zagrajczuk
1
, Michal Palczynski
1
,
and Katarzyna Cholewa-Kowlaska
1
1
AGH University of Science and Technology, Faculty of Materials Science and Ceramics,
Department of Glass Technology and Amorphous Coatings, 30 Mickiewicza Av., 30-059 Krakow,
e-mail: dziadek@agh.edu.pl
One of the biggest challenges in regenerative medicine is promoting sufficient vascularisation of
tissue-engineered constructs. One approach to overcome this challenge is to target the cellular
Hypoxia Inducible Factor (HIF-1α) pathway, which responds to low oxygen concentration (hypoxia)
and results in the activation of numerous pro-angiogenic genes including vascular endothelial growth
factor (VEGF). Copper ions are known to mimic hypoxia by artificially stabilising the HIF-1α
transcription factor [1, 2]. We hypothesized that bioactive glasses with controllable Cu
2+
ion release
could mimic hypoxic condition and induce the coupling of osteogenesis and angiogenesis, which
would be of great interest for applications in bone tissue engineering. A major challenge is obtaining
therapeutic but not cytotoxic concentration of active ions in implantation site. The controlled release
rate of copper ions from bioactive glass is vital for any tissue engineering applications. It is well
known that solubility of glasses is a complex function of chemical composition, structure, material
chemistry, as well as their texture properties. Therefore, in order to be able to model and predict the
solubility behavior of bioactive glasses, and therefore ion release rate, it is important to have an
understanding of the structure and any modifications that may result due to the incorporation of
additional elements.
The effect of CuO substitution for CaO in two glasses with different chemical compositions (mol
%) A2Cu: (54–x)CaO–xCuO–6P
2
O
5
–40SiO
2
and S2Cu: (16–x)CaO–xCuO–4P
2
O
5
–80SiO
2
(x=0, 1, 3,
and 5) stabilized at 700°C on their structure and bioactive properties was investigated. A2Cu group of
glasses were synthetized with the use of sol-gel and melt-quenching method, while S2Cu group of
glasses were produced using melt-quenching technique. The structure of resulting glasses was studied
using FTIR and Raman spectroscopy and X-ray diffraction (XRD). Furthermore, bioactive properties
of materials was assessed using SEM/EDX, FTIR, and XRD methods after 7 and 14 days of
incubation in simulated body fluid (SBF).
The results show that the effect of copper substitution on the structure and crystallization ability
of gel-derived glass strongly depends on SiO2/CaO molar ratio in glass composition. XRD and FTIR
studies indicate that gradual increase of CuO content in both A2 and S2 gel glasses results in the
enhancement of crystallization process. The presence of 3–5 mol% of CuO in calcium-rich gel glass
(A2 group) leads to expansion and disruption of the silicon-oxygen network. While, the addition of
Cu to the silica-rich gel glass (S2 group) does not significantly change the polymerisation of glass
network. In case of melt-derived glasses, results show that copper substitution do not change
significantly structure of A2 material. Glasses remain translucent and have amorphous character, as
demonstrated by XRD, as well as FTIR, and Raman spectroscopy. Further investigations of glass
dissolution and in vitro cell response are needed to determine the real effect of CuO substitution on
the properties of bioactive glasses and to correlate them with their structure.
Keywords: bioactive glasses; FTIR; Raman spectroscopy
Acknowledgments
This work was partially supported by the National Science Centre, Poland (2015/17/N/ST8/00226) and the
Polish Ministry for Science and Higher Education, AGH University of Science and Technology, Faculty of
Materials Science and Ceramics (15.11.160.014).
References
[1] Chengtie Wu et al., Biomaterials 34 (2013) 422.
[2] Shichang Zhao et al., Acta Biomaterialia 14 (2015) 185.
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