Table 1.

The characteristic of principal structures of siloxanes.

No.	Structure	Characteristic
1	Linear	Volatile (e.g., dodecamethylpentasiloxane in cosmetics) and non-volatile liquids (e.g., dimethicone in oral capsules)
2	Cyclic	Volatile liquids (e.g., cyclomethicone in hairspray or creams)
3	Branched	Resins and rubbers, e.g., Soft Skin Adhesives from Dow-Corning company DC 7-9800 Part A, DC 7-9800 Part B in silicone tapes on the skin, or in transdermal systems;
4	Cross-linked (first network)	Resins, rubbers, elastomers (e.g., Cica-Care for the treatment of scars and keloids);
5	Cross-linked (second network)	Resins readily transformed into a three-dimensional network)