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The FT-IR spectra of the reaction of sample without TBOT at (a) 0 min, (b) 0.5 min, (c) 3 min, (d) 9 min, (e) 15 min, (f) 20 min, and (g) 25 min.
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In this work, we have used FT‐IR spectroscopy to study the hydrolysis and polymerization reactions of tetraethyl orthosilicate (TEOS) and polydimethyl‐siloxane (PDMS) in the presence of tetrabutyl orthotitanate (TBOT). These reactions are used for obtaining SiO2–PDMS–TiO2 organically modified silicates (Ormosils). In order to obtain semi‐quantitati...
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... comparing the 600 -400 cm 21 spectral range of Figs. 1 and 2 an increase in intensity is observed in the spectra of Fig. 2. This result must be assigned to some formation of Ti -O -Ti bonds, after TBOT hydrolysis, because the high molar ratio HCl/TBOT used in this work avoids the formation of TiOH gels or precipitates. [31] Figure 3 shows the FT-IR spectra at 15 min of reaction for samples with different TBOT amounts. There appear the same IR bands as those already noted in Figs. 1 and 2. Both the 1200 -1000 cm 21 and 600 -400 cm 21 spectral regions show differences as the TBOT concentration is increased. The bands situated at 1127, 1087, and 1038 cm 21 are observed to increase with the TBOT concentration as it does in the 600-400 cm 21 spectral region, due to the high contribution of TBOT bands. [23,24] In order to obtain semi-quantitative information about the effect of TBOT on the reaction between TEOS and PDMS, we have done a semi-quantitative analysis by deconvolution of the IR spectra using a computer program. In this program each IR band is determined by three parameters: intensity, half width, and wave number, and it has been assumed that the IR bands have a gaussian profile. Figure 4(a) -(c) shows the deconvoluted FT-IR spectra from 1260 to 1000 cm 21 and Fig. 5(a) -(c) shows the deconvolution procedure for the 900 to 760 cm 21 spectral ranges. Both figures correspond to the sample with 7% of TBOT. In such spectra can be observed the changes in the main bands, noted above, at each given ...
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... order to know the influence of TBOT in reactions above noted, a sample was prepared without TBOT, and analyzed by FT-IR spectroscopy. The FT-IR spectra of the reacting solutions, at a given time, are shown in Fig. 1. It must be taken into account that in all cases time t ¼ 0 corresponds to TEOS -PDMS-1/3iPr-OH solution (see Experimental ...
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... the 1300-700 cm 21 region ( Fig. 1), the main bands of the studied reactions can be observed. At 1262 cm 21 , there appears the characteristic An increase can be observed in the small shoulder located at 1180 cm 21 due to the self-condensation of Si-OH groups. The four bands located at 1168, 1104, 1083, and 1031 cm 21 [ Fig. 1(a)] are assigned to TEOS and PDMS molecules (see Table 1). The band located at 1168 cm 21 (CH 3 rocking from TEOS) disappears in spectrum 1(b). The disappearance of this band is in accordance with the high hydrolysis rate of TEOS in a strong acid medium. [18,26] Such hydrolysis produces Et-OH that gives two new and intense bands [spectrum 1(b)] located at 1090 and 1050 cm 21 . However, the width of these bands is due to the contribution of Si-O bonds from both PDMS molecules and self-condensed Si-O-Si bonds from hydrolyzed TEOS. [18,19,26] The iPr-OH gives two more bands located at 1130 and 1162 cm 21 . Spectra 1(c)-(g) show a behavior very close to the spectrum of ...
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... the 1300-700 cm 21 region ( Fig. 1), the main bands of the studied reactions can be observed. At 1262 cm 21 , there appears the characteristic An increase can be observed in the small shoulder located at 1180 cm 21 due to the self-condensation of Si-OH groups. The four bands located at 1168, 1104, 1083, and 1031 cm 21 [ Fig. 1(a)] are assigned to TEOS and PDMS molecules (see Table 1). The band located at 1168 cm 21 (CH 3 rocking from TEOS) disappears in spectrum 1(b). The disappearance of this band is in accordance with the high hydrolysis rate of TEOS in a strong acid medium. [18,26] Such hydrolysis produces Et-OH that gives two new and intense bands [spectrum 1(b)] located at 1090 and 1050 cm 21 . However, the width of these bands is due to the contribution of Si-O bonds from both PDMS molecules and self-condensed Si-O-Si bonds from hydrolyzed TEOS. [18,19,26] The iPr-OH gives two more bands located at 1130 and 1162 cm 21 . Spectra 1(c)-(g) show a behavior very close to the spectrum of ...
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... the spectral region from 1000 to 700 cm 21 [ Fig. 1(a)] two high intensity bands can be observed, which are located at 955 cm 21 (iPr-OH) and 800 cm 21 (TEOS and PDMS) both have a shoulder at 966 cm 21 (TEOS) and 817 cm 21 (iPr-OH), respectively. Also, two low intensity bands can be observed at 909 and 862 cm 21 (PDMS). The change of intensity of these bands from pure PDMS to mixed PDMS -TEOS -iPr-OH [ Fig. 1(a)] is due to the dilution process, which causes the separation of PDMS molecules to break hydrogen bonds from such PDMS molecules. [27] In the spectrum 1(b), is observed a strong band at 952 cm 21 (iPr-OH), and the disappearance of the shoulder located at 966 cm 21 is due to the hydrolysis of TEOS. Such hydrolysis gives a new strong band located at 882 cm 21 (Et-OH). The bands located at 909 and 862 cm 21 , assigned to PDMS, are not readily observable because of the presence of Et-OH, which increases the dilution of the PDMS in the reaction medium. Copolymerization of PDMS molecules with the Si -OH groups formed from the hydrolysis of TEOS [21] gives a new small band located at 850 cm 21 [ Fig. 1(b)]. Andrianov has shown that the synthesis of polymers having inorganic molecular chains, by means of mixed hydrolysis and condensation reactions, leads to the formation of linear or branched structures, and when monomers with functionality greater than two are used, primarily cyclo-linear and cyclo-branched structures are obtained. These cyclo-branched structures give an IR band located at 850 cm 21 . [21] The overlap of iPr-OH and PDMS bands at 817 and 800 cm 21 , respectively, gives a new strong band at 812 cm 21 [ Fig. 1(b)]. The band attributable to PDMS molecules located at 800 cm 21 is very sensitive to the structure of PDMS so that when PDMS has a linear structure the band is located at 800 cm 21 , and when it has a cyclic structure the band shifts to high wavenumber (up to 805 cm 21 ). [27] This latter band overlaps the band located at 817 cm 21 of iPr-OH. According to this, the increase in intensity of the band situated at 812 cm 21 [spectrum 1(b)] can be assigned to the increase in cyclic PDMS molecules, and this gives a decrease in the bands located at 909 and 862 cm 21 . Spectra from 1(c)-(f) show the same above-mentioned bands at 952, 882, 850, and 812 cm 21 . Also, a continuous increase in the intensity of the band located at 850 cm 21 can be observed, which reaches the intensity of the Et-OH band at 882 cm 21 ...
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... the spectral region from 1000 to 700 cm 21 [ Fig. 1(a)] two high intensity bands can be observed, which are located at 955 cm 21 (iPr-OH) and 800 cm 21 (TEOS and PDMS) both have a shoulder at 966 cm 21 (TEOS) and 817 cm 21 (iPr-OH), respectively. Also, two low intensity bands can be observed at 909 and 862 cm 21 (PDMS). The change of intensity of these bands from pure PDMS to mixed PDMS -TEOS -iPr-OH [ Fig. 1(a)] is due to the dilution process, which causes the separation of PDMS molecules to break hydrogen bonds from such PDMS molecules. [27] In the spectrum 1(b), is observed a strong band at 952 cm 21 (iPr-OH), and the disappearance of the shoulder located at 966 cm 21 is due to the hydrolysis of TEOS. Such hydrolysis gives a new strong band located at 882 cm 21 (Et-OH). The bands located at 909 and 862 cm 21 , assigned to PDMS, are not readily observable because of the presence of Et-OH, which increases the dilution of the PDMS in the reaction medium. Copolymerization of PDMS molecules with the Si -OH groups formed from the hydrolysis of TEOS [21] gives a new small band located at 850 cm 21 [ Fig. 1(b)]. Andrianov has shown that the synthesis of polymers having inorganic molecular chains, by means of mixed hydrolysis and condensation reactions, leads to the formation of linear or branched structures, and when monomers with functionality greater than two are used, primarily cyclo-linear and cyclo-branched structures are obtained. These cyclo-branched structures give an IR band located at 850 cm 21 . [21] The overlap of iPr-OH and PDMS bands at 817 and 800 cm 21 , respectively, gives a new strong band at 812 cm 21 [ Fig. 1(b)]. The band attributable to PDMS molecules located at 800 cm 21 is very sensitive to the structure of PDMS so that when PDMS has a linear structure the band is located at 800 cm 21 , and when it has a cyclic structure the band shifts to high wavenumber (up to 805 cm 21 ). [27] This latter band overlaps the band located at 817 cm 21 of iPr-OH. According to this, the increase in intensity of the band situated at 812 cm 21 [spectrum 1(b)] can be assigned to the increase in cyclic PDMS molecules, and this gives a decrease in the bands located at 909 and 862 cm 21 . Spectra from 1(c)-(f) show the same above-mentioned bands at 952, 882, 850, and 812 cm 21 . Also, a continuous increase in the intensity of the band located at 850 cm 21 can be observed, which reaches the intensity of the Et-OH band at 882 cm 21 ...
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... the spectral region from 1000 to 700 cm 21 [ Fig. 1(a)] two high intensity bands can be observed, which are located at 955 cm 21 (iPr-OH) and 800 cm 21 (TEOS and PDMS) both have a shoulder at 966 cm 21 (TEOS) and 817 cm 21 (iPr-OH), respectively. Also, two low intensity bands can be observed at 909 and 862 cm 21 (PDMS). The change of intensity of these bands from pure PDMS to mixed PDMS -TEOS -iPr-OH [ Fig. 1(a)] is due to the dilution process, which causes the separation of PDMS molecules to break hydrogen bonds from such PDMS molecules. [27] In the spectrum 1(b), is observed a strong band at 952 cm 21 (iPr-OH), and the disappearance of the shoulder located at 966 cm 21 is due to the hydrolysis of TEOS. Such hydrolysis gives a new strong band located at 882 cm 21 (Et-OH). The bands located at 909 and 862 cm 21 , assigned to PDMS, are not readily observable because of the presence of Et-OH, which increases the dilution of the PDMS in the reaction medium. Copolymerization of PDMS molecules with the Si -OH groups formed from the hydrolysis of TEOS [21] gives a new small band located at 850 cm 21 [ Fig. 1(b)]. Andrianov has shown that the synthesis of polymers having inorganic molecular chains, by means of mixed hydrolysis and condensation reactions, leads to the formation of linear or branched structures, and when monomers with functionality greater than two are used, primarily cyclo-linear and cyclo-branched structures are obtained. These cyclo-branched structures give an IR band located at 850 cm 21 . [21] The overlap of iPr-OH and PDMS bands at 817 and 800 cm 21 , respectively, gives a new strong band at 812 cm 21 [ Fig. 1(b)]. The band attributable to PDMS molecules located at 800 cm 21 is very sensitive to the structure of PDMS so that when PDMS has a linear structure the band is located at 800 cm 21 , and when it has a cyclic structure the band shifts to high wavenumber (up to 805 cm 21 ). [27] This latter band overlaps the band located at 817 cm 21 of iPr-OH. According to this, the increase in intensity of the band situated at 812 cm 21 [spectrum 1(b)] can be assigned to the increase in cyclic PDMS molecules, and this gives a decrease in the bands located at 909 and 862 cm 21 . Spectra from 1(c)-(f) show the same above-mentioned bands at 952, 882, 850, and 812 cm 21 . Also, a continuous increase in the intensity of the band located at 850 cm 21 can be observed, which reaches the intensity of the Et-OH band at 882 cm 21 ...
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... the spectral region from 1000 to 700 cm 21 [ Fig. 1(a)] two high intensity bands can be observed, which are located at 955 cm 21 (iPr-OH) and 800 cm 21 (TEOS and PDMS) both have a shoulder at 966 cm 21 (TEOS) and 817 cm 21 (iPr-OH), respectively. Also, two low intensity bands can be observed at 909 and 862 cm 21 (PDMS). The change of intensity of these bands from pure PDMS to mixed PDMS -TEOS -iPr-OH [ Fig. 1(a)] is due to the dilution process, which causes the separation of PDMS molecules to break hydrogen bonds from such PDMS molecules. [27] In the spectrum 1(b), is observed a strong band at 952 cm 21 (iPr-OH), and the disappearance of the shoulder located at 966 cm 21 is due to the hydrolysis of TEOS. Such hydrolysis gives a new strong band located at 882 cm 21 (Et-OH). The bands located at 909 and 862 cm 21 , assigned to PDMS, are not readily observable because of the presence of Et-OH, which increases the dilution of the PDMS in the reaction medium. Copolymerization of PDMS molecules with the Si -OH groups formed from the hydrolysis of TEOS [21] gives a new small band located at 850 cm 21 [ Fig. 1(b)]. Andrianov has shown that the synthesis of polymers having inorganic molecular chains, by means of mixed hydrolysis and condensation reactions, leads to the formation of linear or branched structures, and when monomers with functionality greater than two are used, primarily cyclo-linear and cyclo-branched structures are obtained. These cyclo-branched structures give an IR band located at 850 cm 21 . [21] The overlap of iPr-OH and PDMS bands at 817 and 800 cm 21 , respectively, gives a new strong band at 812 cm 21 [ Fig. 1(b)]. The band attributable to PDMS molecules located at 800 cm 21 is very sensitive to the structure of PDMS so that when PDMS has a linear structure the band is located at 800 cm 21 , and when it has a cyclic structure the band shifts to high wavenumber (up to 805 cm 21 ). [27] This latter band overlaps the band located at 817 cm 21 of iPr-OH. According to this, the increase in intensity of the band situated at 812 cm 21 [spectrum 1(b)] can be assigned to the increase in cyclic PDMS molecules, and this gives a decrease in the bands located at 909 and 862 cm 21 . Spectra from 1(c)-(f) show the same above-mentioned bands at 952, 882, 850, and 812 cm 21 . Also, a continuous increase in the intensity of the band located at 850 cm 21 can be observed, which reaches the intensity of the Et-OH band at 882 cm 21 ...
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... it has been shown before, TEOS is hydrolyzed very rapidly (given Si-OH groups and Et-OH), Si-OH groups are self-condensed and copoly- merization reactions (between Si-OH groups and PDMS molecules) occur up to gelling. The latter results give the main changes in spectra of Fig. 1. Such changes are located between 1300 and 700 cm 21 . According to that, since TBOT gives the main IR bands in this spectral range, and because the subject of this work is to know the influence of TBOT on the hydrolysis and polymerization reactions of the TEOS-PDMS system, Fig. 2 shows the spectra of the reacting solution of a sample with 7% of TBOT. The spectra of Fig. 2 may be described in the same way as the spectra of Fig. 1. It can be seen in Fig. 2, the fast hydrolysis of TEOS, copolymerization reaction, and self- condensation reaction noted above. Therefore, the bands from these reactions are situated at almost the same wavenumber. On the other hand, the main bands of TBOT are placed at 1125, 1085, and 1035 cm 21 [23,24] (see Table 1). The first band overlaps with that of iPr-OH and last two bands overlap with those of PDMS, Et-OH, and Si-O-Si bonds from self-condensed Si-OH groups. Such overlaps give both displacement of the bands (at 1127, 1087, and 1038 cm 21 ) and broadening in the 1000-1250 spectral range of Fig. 2. The broadening of spectra as a function of time in Fig. 2, suggest that the Ti-O-C bonds are not hydrolyzed totally and then the formation of Si-O-Ti bonds is so small that the band of Si-O-Ti bonds located at 920-950 cm 21 [11,12,21,28 -30] is not easy observable in the spectra. However, as it will be shown below, between 920 and 950 cm 21 there appears a very low intensity band that can be followed during the reaction time. Therefore, in the 1000-700 cm 21 spectral range, there appears only the same bands as those of Fig. 1 because there exists only contributions from Et-OH, iPr-OH, PDMS, and TEOS. On the other hand, the band located at 850 cm 21 , due to copolymerization reactions between PDMS and Si-OH groups, increases in intensity during the first minutes of reaction and remains with the same intensity until the ...
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... it has been shown before, TEOS is hydrolyzed very rapidly (given Si-OH groups and Et-OH), Si-OH groups are self-condensed and copoly- merization reactions (between Si-OH groups and PDMS molecules) occur up to gelling. The latter results give the main changes in spectra of Fig. 1. Such changes are located between 1300 and 700 cm 21 . According to that, since TBOT gives the main IR bands in this spectral range, and because the subject of this work is to know the influence of TBOT on the hydrolysis and polymerization reactions of the TEOS-PDMS system, Fig. 2 shows the spectra of the reacting solution of a sample with 7% of TBOT. The spectra of Fig. 2 may be described in the same way as the spectra of Fig. 1. It can be seen in Fig. 2, the fast hydrolysis of TEOS, copolymerization reaction, and self- condensation reaction noted above. Therefore, the bands from these reactions are situated at almost the same wavenumber. On the other hand, the main bands of TBOT are placed at 1125, 1085, and 1035 cm 21 [23,24] (see Table 1). The first band overlaps with that of iPr-OH and last two bands overlap with those of PDMS, Et-OH, and Si-O-Si bonds from self-condensed Si-OH groups. Such overlaps give both displacement of the bands (at 1127, 1087, and 1038 cm 21 ) and broadening in the 1000-1250 spectral range of Fig. 2. The broadening of spectra as a function of time in Fig. 2, suggest that the Ti-O-C bonds are not hydrolyzed totally and then the formation of Si-O-Ti bonds is so small that the band of Si-O-Ti bonds located at 920-950 cm 21 [11,12,21,28 -30] is not easy observable in the spectra. However, as it will be shown below, between 920 and 950 cm 21 there appears a very low intensity band that can be followed during the reaction time. Therefore, in the 1000-700 cm 21 spectral range, there appears only the same bands as those of Fig. 1 because there exists only contributions from Et-OH, iPr-OH, PDMS, and TEOS. On the other hand, the band located at 850 cm 21 , due to copolymerization reactions between PDMS and Si-OH groups, increases in intensity during the first minutes of reaction and remains with the same intensity until the ...
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... it has been shown before, TEOS is hydrolyzed very rapidly (given Si-OH groups and Et-OH), Si-OH groups are self-condensed and copoly- merization reactions (between Si-OH groups and PDMS molecules) occur up to gelling. The latter results give the main changes in spectra of Fig. 1. Such changes are located between 1300 and 700 cm 21 . According to that, since TBOT gives the main IR bands in this spectral range, and because the subject of this work is to know the influence of TBOT on the hydrolysis and polymerization reactions of the TEOS-PDMS system, Fig. 2 shows the spectra of the reacting solution of a sample with 7% of TBOT. The spectra of Fig. 2 may be described in the same way as the spectra of Fig. 1. It can be seen in Fig. 2, the fast hydrolysis of TEOS, copolymerization reaction, and self- condensation reaction noted above. Therefore, the bands from these reactions are situated at almost the same wavenumber. On the other hand, the main bands of TBOT are placed at 1125, 1085, and 1035 cm 21 [23,24] (see Table 1). The first band overlaps with that of iPr-OH and last two bands overlap with those of PDMS, Et-OH, and Si-O-Si bonds from self-condensed Si-OH groups. Such overlaps give both displacement of the bands (at 1127, 1087, and 1038 cm 21 ) and broadening in the 1000-1250 spectral range of Fig. 2. The broadening of spectra as a function of time in Fig. 2, suggest that the Ti-O-C bonds are not hydrolyzed totally and then the formation of Si-O-Ti bonds is so small that the band of Si-O-Ti bonds located at 920-950 cm 21 [11,12,21,28 -30] is not easy observable in the spectra. However, as it will be shown below, between 920 and 950 cm 21 there appears a very low intensity band that can be followed during the reaction time. Therefore, in the 1000-700 cm 21 spectral range, there appears only the same bands as those of Fig. 1 because there exists only contributions from Et-OH, iPr-OH, PDMS, and TEOS. On the other hand, the band located at 850 cm 21 , due to copolymerization reactions between PDMS and Si-OH groups, increases in intensity during the first minutes of reaction and remains with the same intensity until the ...
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... copolymerization reaction between both Si -OH and/or Ti -OH groups from isolated molecules or from condensed structures, and OH groups of silanol terminated PDMS molecules can be studied from the evolution of the 850 cm 21 band showed in Fig. 10. It is observed that the integrated intensity of this band increases with the reaction time for all concentrations of TBOT added. The higher slope occurs for the firsts 20 min of reaction, and then shows a slow increase with time until gelling. It is observed that the higher integrated intensity corresponds to the sample with the higher amount of TBOT, showing that TBOT increases the Si -O -PDMS and Ti -O -PDMS polycondensation reactions. This result is in accordance with that of Andrianov [21] and Babonneau et al., [36] which showed that TBOT could also catalyze the condensation reactions of PDMS units into cyclo-branched structures and long PDMS chains. On the other hand, cross-linked structures increase during the whole reaction time. A similar behavior is observed for polycondensation reac- tions, which increase with time. The gelling time is dependent on the relative concentration of cross-linked, linear, and poly-condensed structures, all of them being dependent on the TBOT concentration in the reaction ...
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... Finally, both solutions were mixed using the following relations: PVA:HA = 10:1 and 5:1. The hydrolysis-condensation (crosslinking) reactions took place among PVA, TEOS, APTES, and PDMS [28][29][30][31] at room temperature under stirring conditions for 1 h. After that, the solution was dialyzed (MWCO of 6000-8000, Spectrum ® Laboratories, Piscataway, NJ, USA) using ultrapure water to eliminate the excess of EDC/NHS. ...
... Other relevant bands demonstrating the chemical bonding between macromolecules of PVA and HA polymers and the siloxane organic-inorganic network to form the nanofiber mats can be observed in the FT-IR spectra: (1) the band at 1560 cm −1 is assigned to bending vibrations (δ N−H ) of amide II due to N − H groups [37,38]. This results from the chemical modification of sodium hyaluronate with APTES [6,27] and confirms the presence of HA-APTES bonding within the nanofiber chemical composition; (2) from hydrolysis reactions, the bands at 920 cm −1 and 895 cm −1 are assigned to Si − OH stretching due to silanol groups in hydrolyzed TEOS and to asymmetric stretching ϑ a (Si − O) in Si − OH bonds from hydroxyl-terminated PDMS, respectively; (3) the formation of siloxane structures (Q-D units) due to condensation is observed at 850 cm −1 , corresponding to (TEOS) Si − O − Si (PDMS) bonds; (4) the band at 1100 cm −1 can be assigned to both asymmetric stretch- [21]; (5) the band at 790 cm −1 assigned to Si − O bonds due to silicon tetrahedron [SiO 4 ] and Si − C bonds due to PDMS and APTES molecules [6,28,30]. ...
Hyaluronan (HA) is a natural biodegradable biopolymer; its biological functions include cell adhesion, cell proliferation, and differentiation as well as decreasing inflammation, angiogenesis, and regeneration of damaged tissue. This makes it a suitable candidate for fabricating nanomaterials with potential use in tissue engineering. However, HA nanofiber production is restricted due to the high viscosity, low evaporation rate, and high surface tension of HA solutions. Here, hybrids in the form of continuous and randomly aligned polyvinyl alcohol (PVA)–(HA)–siloxane nanofibers were obtained using an electrospinning process. PVA–HA fibers were crosslinked by a 3D siloxane organic–inorganic matrix via sol-gel that restricts natural hydrophilicity and stiffens the structure. The hybrid nanofiber mats were characterized by FT-IR, micro-Raman spectroscopy, SEM, and biological properties. The PVA/HA ratio influenced the morphology of the hybrid nanofibers. Nanofibers with high PVA content (10PVA-8 and 10PVA-10) form mats with few beaded nanofibers, while those with high HA content (5PVA-8 and 5PVA-10) exhibit mats with mound patterns formed by “ribbon-like” nanofibers. The hybrid nanofibers were used as mats to support osteoblast growth, and they showed outstanding biological properties supporting cell adhesion, cell proliferation, and cell differentiation. Importantly, the 5PVA-8 mats show 3D spherical osteoblast morphology; this suggests the formation of tissue growth. These novel HA-based nanomaterials represent a relevant advance in designing nanofibers with unique properties for potential tissue regeneration.
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... The absorption bands at 1021 and 1092 cm −1 are due to the stretching vibration of the Si-O-Si group in the PDMS structure, and the absorption band at 1260 cm −1 is attributed to the symmetrical deformation of the -CH 3 group in the -Si(CH 3 ) 2 -group. The absorption band at 802 cm −1 corresponds to Si-C vibration [30][31][32][33][34]. In the spectrum of PIS, absorption bands at 1779 cm −1 due to imide C=O asymmetric stretching, at 1726 cm −1 due to imide C=O symmetrical stretching, and at 1363 cm −1 due to C-N stretching were observed. ...
... The absorp 1021 and 1092 cm −1 are due to the stretching vibration of the Si-O-Si group structure, and the absorption band at 1260 cm −1 is attributed to the deformation of the -CH3 group in the -Si(CH3)2-group. The absorption ban corresponds to Si-C vibration [30][31][32][33][34]. In the spectrum of PIS, absorption b cm −1 due to imide C=O asymmetric stretching, at 1726 cm −1 due to imide C=O stretching, and at 1363 cm −1 due to C-N stretching were observed. ...
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... An extensive broad band around 2900 cm -1 is due to the overlapping of various C-H stretching vibrations in CH 3 groups present in the TEOS and DBTDL cured PDMS. The characteristic peak of O-H stretch around 3300 cm -1 is absent in all PDMS film samples, indicating the proper curing reaction between PDMS dispersion and curates TEOS, accelerator DBTDL [30,31]. The band at 1940 cm -1 is attributed to the ester linkage present in the DBTDL accelerator. ...
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... The chemical composition of WT coating was investigated by FT-IR and XPS. Figure 5a shows the FT-IR spectrum of WT coating, where the bands at 2964 cm −1 , 2907 cm −1 , and 1259 cm −1 can be referred to C-H bond in CH 3 (Téllez-Jurado et al. 2006) and the peaks at 1011 cm −1 and 797 cm −1 can be assigned to Si-O and Si-C of PDMS (Liu et al. 2021a), respectively. In addition, the band at 434 cm −1 , whose intensity rises with the increase of WT content, belongs to the Ti-O bond in WT. ...
Due to the semi-closed structure of the tunnel, serious air pollution in tunnels from vehicle exhaust becomes an issue which needed to be addressed. Among the exhaust, nitric oxide (NO) is typically considered as one of the main pollutants. In this paper, a superhydrophobic photocatalytic coating was fabricated by a spraying method by airbrush with a WO3/TiO2 photocatalysis for NO degradation. The water advanced contact angle (WACA) of the coating reached 166.32°, and the WACA was still above 145° after the 30 times abrasion test. The coating exhibited an excellent ability to remove inorganic and organic pollutants. Also, the NO degradation efficiency of this superhydrophobic coating under ultraviolet and visible light sources and humid environments was tested. When the relative humidity reached 98%, the NO degradation efficiency of the coating remained unchanged under visible light irradiation compared with the relative humidity of 45%. In addition, the coating exhibited prominent stability of NO degradation during the cyclic test. Furthermore, the WT coating showed stability and synergy of self-cleaning and photocatalysis toward NO degradation, which ensured the long-term use of the coating. Finally, a synergistic mechanism for self-cleaning and photocatalysis was proposed. This may provide a new idea and support for the application of photocatalytic technology in the degradation of NO in the tunnel.
... The reason for this change is due to the introduction of Si-O-Si. 28,29 Besides, the increase in the peaks at 2886 cm −1 and 2926 cm −1 indicates the introduction of long-chain alkane compounds. Sample A3 is the infrared spectrum of GPTMS-SiO 2 coated on the basis of A2. ...
In this study, we composite coated silica nanoparticles with functional groups on paper to form a double-size surface roughness, then hexafluorobutyl methacrylate was polymerized with 3-trimethoxymethylsilyl propyl methacrylate (TSPM), a one-step method is used to prepare a hydrophobic polymer with low surface energy (PHFMA-co-TSPM), and the superhydrophobic surface was prepared by hydrophobic treatment of the paper with a low surface energy polymer. Further tests show that the superhydrophobic paper prepared by this method not only exhibits extremely strong hydrophobicity, but also has strong stability, transparency, and self-cleaning properties.
... The resonances attributed to PDMS at 650 cm − 1 (CH 3 rocking), 1263 cm − 1 (symmetric bending of the -CH 3 ), and 800 cm − 1 . The left-shifted band (up to 805 cm − 1 ) corresponds to a cyclic structure of the polymeric chain [33][34][35], the one at 850 cm − 1 (PDMS/TEOS) is assigned to the copolymerization of PDMS with the Si-OH groups formed from the hydrolysis of TEOS [23,36,37]. It is interesting to note that the samples SiO 2 @TiO 2 -M1 and M4 are characterized by PDMS bands of different signal intensities and widths as it can be observed. ...
Among the different properties of the hydrophobic semiconductor surfaces, self-cleaning promoted by solar illumination is probably one of the most attractive from the technological point of view. The use of sonochemistry for nanomaterials' synthesis has been recently employed for the associated shorter reaction times and efficient route for control over crystal growth and the management of the resulting material's photocatalytic properties. Moreover, the sol-gel method coupled to sonochemistry modifies the chemical environment, with reactive species such as •OH and H2O2, which yield a homogeneous synthesis. Therefore, in the following investigation, the sol-gel method was coupled to sonochemistry to synthesize a SiO2@TiO2 composite, for which the sonochemical amplitude of irradiation was varied to determine its effect on the morphology and mechanical and self-cleaning properties. SEM and AFM characterized the samples of [email protected] composite, and while the micrographs indicate that a high ultrasonic energy results in an amorphous SiO2@TiO2 composite with a low rugosity, which was affected in the determination of the contact angle on the surface. On the other hand, FTIR analysis suggests a significant change in both SiO2-SiO and SiO2-TiO2 chemical bonds with changes in vibrations and frequency, corroborating an important influence of the sonochemical energy contribution to the hydrolysis process. Raman spectroscopy confirms the presence of an amorphous phase of silicon dioxide; however, the vibrations of TiO2 were not visible. The evaluation of hydrophobic and self-cleaning properties shows a maximum of ultrasonic energy needed to improve the contact angle and rhodamine B (RhB) removal.
... The peaks at 1130 and 2962 cm − 1 originate from the stretching vibrations of Si-O-Si and CH 3 groups, respectively [25]. The peak at 1259 cm − 1 is the symmetric deformation of the CH 3 groups, and the peak at 808 cm − 1 can be the stretching vibration of Si-C [26]. It should be noted that the peak of BNNSs at 1388 cm − 1 increases gradually with the concentration of BNNSs, indicating that BNNSs have been fully mixed with PDMS. ...
The hexagonal boron nitride nanosheets (BNNSs) are one of the 2-dimensional(2D) materials, and have been explored for their applications in nanoelectronics etc, owing to their unique properties. Here, BNNSs are utilized to develop a high-performance hybrid piezo/triboelectric nanogenerator (PTEG). BNNSs of a few percentages in weight are incorporated into polydimethylsiloxane (PDMS) to form composites that are able to produce piezo-electric voltages up to ~ 5.4 V with d 33 ~ 12 pC/N. A PTEG composed of BNNS-PDMS and polyamide-6 (PA6) membranes (20 × 20 mm 2) demonstrates a current density of ~ 230 mA m − 2 , an output voltage of ~ 1870 V and a maximum power density of ~ 103.7 Wm − 2 , more than three times higher than those of the control PDMS/PA6 nanogenerator. Electric polarization of the BNNS-PDMS membranes can further enhance the output of PTEGs. Detailed investigation reveals that the dramatically enhanced performance originates from the synergy of piezoelectric effect of BNNSs and increased electron affinity of BNNS-PDMS membranes, demonstrates the excellent potential of BNNS-based PTEGs.
... The spectrum for the TEOS-FAS sol is shown in Figure 1, where we can observe the wide and intensive 3345 cm −1 peak corresponding to O-H absorbance (solvent and silane) and the 2974-2889 cm −1 intensive sharp peaks corresponding to the asymmetric and symmetric stretch vibrations of the C-H bonds (sp 3 ) at the left part of the spectrum [47][48][49][50]. To the right, we see a sharp medium-height peak of 1654 cm −1 in regards to the scissoring vibration of the N-H bond. ...
Tetraethyl orthosilicate (TEOS) is extensively used in the conservation of stone-built cultural heritage, which is often subjected to water-induced degradation processes. The goal of this study was to produce and study a TEOS-based material with the ability to repel liquid water. A sol solution of TEOS and 1H,1H,2H,2H-perfluorooctyl triethoxysilane (FAS) was prepared and deposited on marble. The static contact angles (CAs) of water drops on the coated marble surface were >170° and the sliding angles (SA) were <5°, suggesting that superhydrophobicity and water repellency were achieved on the surface of the synthesized TEOS-based coating. FTIR and SEM-EDS were employed to characterize the produced coating. The latter offered good protection against water penetration by capillarity, reducing the breathability of marble only by a small extent and with practically no effect on its aesthetic appearance. The durability of the coating was evaluated through various tests that provided very promising results. Finally, the versatility of the method was demonstrated as the TEOS-based coating was successfully deposited onto glass, brass, wood, silicon, paper and silk, which obtained extreme wetting properties.
... In all spectra, the bands at ca. 400 and 850 cm −1 are associated with a hybrid cross-link between SiO 2 (Q units)− PDMS (D units) structures. 57 The first band is related to the introduction of hybrid SiO 4 −(CH 3 ) 2 ·SiO 2 bonds in the silica network, since its value dropped compared to values obtained for pure silica gel (usually close to ca. 460 cm −1 ). In the same way, PDMS pure chains exhibit weak bands at ca. 860 cm −1 , corresponding to symmetrical rocking of CH 3 groups. ...
Poly(dimethylsiloxane) (PDMS)-SiO2-CaO-based hybrid materials prepared by sol-gel have proved to be very promising materials for tissue engineering applications and drug-delivery systems. These hybrids are biocompatible and present osteogenic and bioactive properties supporting osteoblast attachment and bone growth. The incorporation of therapeutic elements in these materials, such as boron (B) and calcium (Ca), was considered in this study as an approach to develop biomaterials capable of stimulating bone regeneration. The main purpose of this work was thus to produce, by sol-gel, bioactive and biocompatible hybrid materials of the PDMS-SiO2-B2O3-CaO system, capable of a controlled Ca and B release. Different compositions with different boron amounts were prepared using the same precursors resulting in different monolithic materials, with distinct structures and microstructures. Structural features were assessed by Fourier transform infrared (FT-IR) spectrometry and solid-state nuclear magnetic resonance (NMR) techniques, which confirmed the presence of hybrid bonds (Si-O-Si) between organic (PDMS) and inorganic phase (tetraethyl orthosilicate (TEOS)), as well as borosiloxane bonds (B-O-Si). From the 11B NMR results, it was found that Ca changes the boron coordination, from trigonal (BO3) to tetrahedral (BO4). Scanning electron microscopy (SEM) micrographs and N2 isotherms showed that the incorporation of boron modifies the material's microstructure by increasing the macroporosity and decreasing the specific surface area (SSA). In vitro tests in simulated body fluid (SBF) showed the precipitation of a calcium phosphate layer on the material surface and the controlled release of therapeutic ions. The cytocompatibility of the prepared hybrids was studied with bone marrow stromal cells (ST-2 cell line) by analyzing the cell viability and cell density. The results demonstrated that increasing the dilution rate of extraction medium from the hybrids leads to improved cell behavior. The relationship between the in vitro response and the structural and microstructural features of the materials was explored. It was shown that the release of calcium and boron ions, determined by the hybrid structure was crucial for the observed cells behavior. Although not completely understood, the encouraging results obtained constitute an incentive for further studies on this topic.
