Author Contributions
Conceptualization, Q.W. and M.F.; methodology, Q.W. and M.F.; validation, Q.W. and M.F.; investigation, Q.W.; resources, M.F.; data curation, Q.W.; writing—original draft preparation, Q.W.; writing—review and editing, M.F. and K.I.; visualization, Q.W.; supervision, M.F.; project administration, M.F.; funding acquisition, M.F. All authors have read and agreed to the published version of the manuscript.
Figure 1.
Transmission electron microscope images (TEM) and energy spectrum scanning (EDS) images of hollow particles with different PAA contents ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 1.
Transmission electron microscope images (TEM) and energy spectrum scanning (EDS) images of hollow particles with different PAA contents ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 2.
Statistical results of composite particle diameter and the shell thickness distribution of composite hollow particles ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 2.
Statistical results of composite particle diameter and the shell thickness distribution of composite hollow particles ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 3.
Thermogravimetry test results for the hollow particles and pure polyacrylic acid (PAA) under different PAA contents ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 3.
Thermogravimetry test results for the hollow particles and pure polyacrylic acid (PAA) under different PAA contents ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 4.
Infrared spectral analysis results (FT-IR) for hollow particles with different PAA contents ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 4.
Infrared spectral analysis results (FT-IR) for hollow particles with different PAA contents ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 5.
Zeta potential titration results for the composite particles ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 5.
Zeta potential titration results for the composite particles ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 6.
Nitrogen isothermal adsorption curves of hollow particles with different PAA contents ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 6.
Nitrogen isothermal adsorption curves of hollow particles with different PAA contents ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 7.
The t-plot curves under the nitrogen adsorption of composite hollow particles with different PAA contents ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 7.
The t-plot curves under the nitrogen adsorption of composite hollow particles with different PAA contents ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 8.
Water vapor isothermal adsorption curves of hollow particles with different PAA contents ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 8.
Water vapor isothermal adsorption curves of hollow particles with different PAA contents ((a) = not washed, (b) = washed once, (c) = washed twice, (d) = PAA completely removed).
Figure 9.
Comparison of the adsorption capacity of water molecules in the different shell structures of the hollow nanoparticles (silica shell, silica/PAA shell, and PAA/silica/PAA shell).
Figure 9.
Comparison of the adsorption capacity of water molecules in the different shell structures of the hollow nanoparticles (silica shell, silica/PAA shell, and PAA/silica/PAA shell).
Figure 10.
Structural change mechanism diagram of composite particles.
Figure 10.
Structural change mechanism diagram of composite particles.
Table 1.
The average value results of hollow particle diameter, shell thickness, and inner diameter (a = not washed, b = washed once, c = washed twice, d = PAA completely removed).
Table 1.
The average value results of hollow particle diameter, shell thickness, and inner diameter (a = not washed, b = washed once, c = washed twice, d = PAA completely removed).
Sample | Particle Diameter, nm | Shell Thickness, nm | Particle Inner Diameter, nm |
---|
a | 79.71 | 27.75 | 51.96 |
b | 81.86 | 26.08 | 55.78 |
c | 86.32 | 25.57 | 60.35 |
d | 77.19 | 15.55 | 61.64 |
Table 2.
Thermal weight-loss results for composite nanoparticles under different wash conditions (a = not washed, b = washed once, c = washed twice, d = roasted to remove the PAA).
Table 2.
Thermal weight-loss results for composite nanoparticles under different wash conditions (a = not washed, b = washed once, c = washed twice, d = roasted to remove the PAA).
Sample | Weight Loss, % |
---|
a | 17.74% |
b | 14.07% |
c | 13.45% |
d | 0.28% |
Table 3.
Determination results of specific surface area and pore volume analyses of hollow particles with different PAA contents under nitrogen adsorption mass (a = not washed, b = washed once, c = washed twice, d = PAA completely removed).
Table 3.
Determination results of specific surface area and pore volume analyses of hollow particles with different PAA contents under nitrogen adsorption mass (a = not washed, b = washed once, c = washed twice, d = PAA completely removed).
Sample | Specific Surface Area (BET), m2/g | Total Full Fine Pore Volume, cm3/g |
---|
a | 97.625 | 0.4114 (P/P0 = 0.982) |
b | 58.147 | 0.3863 (P/P0 = 0.982) |
c | 57.445 | 0.3614 (P/P0 = 0.98) |
d | 71.601 | 0.5547 (P/P0 = 0.986) |
Table 4.
External surface area, micropore volume, and average micropore diameter of hollow particles with different PAA contents (a = not washed, b = washed once, c = washed twice, d = PAA completely removed).
Table 4.
External surface area, micropore volume, and average micropore diameter of hollow particles with different PAA contents (a = not washed, b = washed once, c = washed twice, d = PAA completely removed).
Sample | External Surface Area, m2/g | Micropore Volume, cm3/g | Micropore Diameter, nm |
---|
a | 14.03 | 17.59 | 0.84 |
b | 13.28 | 6.56 | 0.80 |
c | 13.85 | 6.63 | 0.80 |
d | 19.19 | 6.94 | 0.90 |
Table 5.
Determination results of the specific surface area and pore volume of hollow particles with different PAA contents under water vapor adsorption mass (a = not washed, b = washed once, c = washed twice, d = PAA completely removed).
Table 5.
Determination results of the specific surface area and pore volume of hollow particles with different PAA contents under water vapor adsorption mass (a = not washed, b = washed once, c = washed twice, d = PAA completely removed).
Sample | Specific Surface Area (BET), m2/g | Total Full Fine Pore Volume, cm3/g |
---|
a | 184.78 | 0.1154 (P/P0 = 0.983) |
b | 206.75 | 0.1141 (P/P0 = 0.990) |
c | 220.00 | 0.1166 (P/P0 = 0.990) |
d | 77.22 | 0.0851 (P/P0 = 0.981) |
Table 6.
Features and moisture sorption properties of various composite silica nanoparticles.
Table 6.
Features and moisture sorption properties of various composite silica nanoparticles.
Composite Silica Nanoparticle Type | Particle Size, nm | Moisture Sorption Capacity, wt % | Reference |
---|
PE/silica nanoparticles | 12 | 0.9 ± 0.03 | [46] |
Cellulose fibers/silica nanoparticles | 192 ± 45 | 12.3 | [47] |
PEG/silica nanoparticles | 174.7 ± 18.9 | 8 | [48] |
Mesoporous silica gel | | 8 ± 2 | [49] |
HSNPs | 77.19 | 75.8 (P/P0 = 0.6) | this work |
PAA/HSNPs | 86.32 | 145.9 (P/P0 = 0.6) | this work |
Table 7.
Summary of the physical and chemical properties of PAA composite hollow nanoparticles.
Table 7.
Summary of the physical and chemical properties of PAA composite hollow nanoparticles.
Layer Number of Hollow Nanoparticles | Particle Size, nm | Shell Thickness, nm | Shell Structure | PAA Content, % |
---|
1 | 77.19 | 15.55 | SiO2 | 0 |
2 | 79.71 | 27.75 | PAA/SiO2 | 17.46 |
3 | 86.32 | 25.57 | PAA/SiO2/PAA | 13.17 |