Cocoon-shaped hollow mesoporous silica ellipsoids controlled by interfacial destabilization growth kinetics

Figures & data

Table 1. Starting material compositions and properties of the products.

Sample	NH4OH/mL	H2O/mL	Morphology and structure
7	307.5	405	Spheres (hexagonal order)
6	205	270	Rods (hexagonal order)
5	153.75	202.5	Cocoon-shaped hollow mesoporous silica
4	102.5	135	Cocoon-shaped hollow mesoporous silica
3	68.3	90	Cocoon-shaped hollow mesoporous silica
2	51.25	67.5	Cocoon-shaped hollow mesoporous silica
1	25.625	33.75	Needle-like pores and taro-like stripes

The molar ratio of CTAB, TEOS and TMB is kept constant at 1:8:8 (2 g CTAB, 10 mL TEOS and 6 mL TMB), whereas the volume amounts of NH₄OH and H₂O are altered to observe the variation in the overall morphologies of silica samples prepared under different solution concentrations.

Figure 1. (A-G) SEM images and (a-g) TEM images of Sample 7 to Sample 1. (H) Comparison of FT-IR Spectrum between Sample 1, 4 and 6. (h) Effect of solution concentration to average particle size of the resulting samples.

Figure 2. (a) Self-assembly and related behavior of CTAB, TEOS, and TMB in solution. The formation mechanism of mesoporous silicas in (b) dilute solution and (c) concentrated solution.

Figure 3. (a, e) XRD patterns, (b, f) N₂ adsorption-desorption isotherms, (c, g) the corresponding BJH-adsorption pore size distribution curves and (d, h) particle size distribution curves of the resulting materials: (a-d) MCM-41-type mesoporous silicas in dilute solution and (e-h) cocoon-shaped hollow mesoporous silicas in concentrated solution.

Figure 4. The nonequilibrium deposition/diffusion behavior of rod-like micelles on the emulsion surface, supposing a two-dimensional facet on the spherical emulsion subject to simple harmonic perturbation ${\delta }_m\cos \left(m\theta \right)$.

Figure 5. Representative comparison between (a-d) theoretical simulations based on Equation (4)(4) $r=R+{\delta }_m\cos \left(m\theta \right)$(4) ($R=216$, ${\delta }_m=0.05$) and (e) experimental results. Representative theoretical simulations of the morphology on the zOx plane with (a) a steady-state diffusion of $m=0$, simple harmonic perturbation of (b) $m=8$, (c) $m=12$, and (d) $m=16$.