Quantitative Analysis and Efficient Surface Modification of Silica Nanoparticles

Table 1

Measured numbers of silanol and amine sites on the various silica surfaces from references as well as this work.

	Type of silica	Number of silanol sites (ea/nm^2)	Number of amine sites (ea/nm^2)	Method (reference)
(1)	Aerosol	4.8	1.6	IR [26]
(2)	Fumed silica	7	2.3	Inverse reaction chromatography [27]
(3)	Colloidal silica	3.3∼6.6	1.2∼2.2	IR [28]
(4)	SiO2-APTMS		2.7 ± 0.35	Titration
(5)	SiO2-DETAS		7.7 ± 0.19	′′
(6)	SiO2-EDA		6.8 ± 1.10	′′
(7)	SiO2-APTMS		0.44 ± 0.01	Absorption
(8)	SiO2-DETAS		1.3 ± 0.08	′′
(9)	SiO2-EDA		0.99 ± 0.07	′′