Novel Mesoporous Silica Materials with Hierarchically Ordered Nanochannel: Synthesis with the Assistance of Straight-Chain Alkanes and Application

Table 1

Straight-chain alkanes as swelling agents in the preparation of MSM.

Carbon atoms () of alkanes ()	Surfactant	Parameters of synthesis				Pore size (nm)	XRD pattern and TEM image	Morphology	Salt	Ref.
		Molar ratio of silica precursor to surfactant	Molar ratio of alkane to surfactant	Temperature of hydrolysis (°C)	Solvent
5~8	CTAB	6.25	1	nd	NaOH	4.2~5.1	oh	nd	—	[48]
9~15						6.2~7.4
>15						6.4~7.0
10	P123	59.2	237	40	HCl	12.1	oh	Platelet-like	NH4F	[34]
			16.4			—		Short fiber-like
6	P123	59.6	240	<17	HCl	15.7	oh	nd	NH4F	[37]
7				<22		15.0
9				<27		13.4
6	P123	62.5	239.3	15	HCl	12~18	oh	nd	NH4F	[49]
8, 9	Triblock copolymer	60	0–298	35	HCl	10.3~14.1	dm	nd	NH4F	[50]
10, 13, 16, 20						8.4~10.1	oh	nd
8	P123	48	235	25	HCl	13	2dp	Nanotube bundles	NH4F	[43]
10	P123	48	134	30	HCl	12	2dp	Nano-fibers	NH4F
				40		50	dv	Multilamellar vesicles
				60		35	dm	MCF
6	P123	60	235		HCl	15.7	oh	Bunch-like	NH4F	[51]
7						15.0		Dripstone-like
8						nd	oh	Rod-like
9						13.4	oh	Flat-like
10						12.0	oh	Kernel-like
12						12.0	oh	Column-like
10			135			nd	oh	Chain-like
10			755			nd	oh	Monolith-like
10		48	235			nd	oh	Fiber-like
10		77				nd	oh	Platelet-like
10		110				nd	oh	Film-like
10	P123	41.4~59.6	119~310	40	HCl	~12.2	oh	Cocoon-like	NH4F	[52, 53]
6	P123	41.4	390	40	HCl	10	dm	MCF	NH4F	[53]
12			197.5			11	2dp	Nanotube bundles

oh: ordered hexagonal; dm: disordered MCF; 2dp: 2-dimensionally parallel; dv: disordered vesicles; nd: not demonstrated. Alkane was added into P123-H₂O/HCl solution before the addition of silica precursor. Alkane and silica precursor were premixed and then added into P123-HCl solution. Only disordered MCF could be obtained without NH₄F. 1.07 M. 1.30 M. 0.43 M. 1.20 M. 1.1 M. Disordered mesostructure will arise if the hydrolysis temperature is higher than the critical value for each alkane. [Poly(ethylene glycol)₂₀-poly(propylene glycol)₇₀-poly(ethylene glycol)₂₀] (Dai-ichi Kogyo Seiyaku, Japan). Surfactant was added into deionized water to form a surfactnat-H₂O solution, followed by the addition of TEOS and HCl, step by step. A clear separation of decane-P123-water mixture leads to upper alkane-rich layer and water-rich layer. The upper decane-rich layer was removed and then TEOS was added. The molecular ratios of alkane/P123 and TEOS/P123 were all calculated by the amount of alkane, P123, and TEOS added into the system.