Synthesis of Silica Nanoparticles by Sol-Gel: Size-Dependent Properties, Surface Modification, and Applications in Silica-Polymer Nanocomposites—A Review

Table 1

Size of the primary particles reported in the literature.

Source	Primary particle size^a (nm)	Method
Bogush and Zukoski [19]	2–4	Prediction^b
Bailey and Mecartney [20]	20	cryo-TEM
Lee et al. [21]	10–20	Prediction^b
Green et al. [22]	10.3^c or 20.7^d	SAXS
Rahman et al. [23]	7^d	TEM

^aRefers to diameter (d); ^bPrediction based on controlled aggregation model;
^cin methanol, ^din ethanol. Calculated using the formula d = 2 × 𝑅_𝑔 × (5/3)^0.5 [22].