Comparison of critical aggregation concentrations (CAC) and surface tension at that CAC (σ_CAC) of the gemini surfactants synthesized by us and literature data for others.

	Compound	Type of surfactant	Ra	CAC (mM)	σ CAC (mN m−1)	Ref.
1	Sodium salt of 2b	Anionic	12	20	44.0	This paper
2	Sodium salt of 2c	Anionic	20	2	39.6
3	Sodium salt of 2d	Anionic	28	0.025	31.4
4	C5H11COONa	Anionic	6	730	Conduct	27
5	C9H19COONa	Anionic	10	74.5	32.6	28
6	C13H27COONa	Anionic	14	6.90	34.5	29
7	N,N′-Bisdodecyl-serine-aminopropane	Anionic	24	0.27	33.2	12
8	N,N′-Bisdodecyl-serine-aminohexane	Anionic	24	0.40	32.1	12
9	Sodium-1,2-bis-N-dioctyl-cystine	Anionic	24	0.001	40.8	30
10	Sodium didecaminecystine	Anionic	20	0.75	38.0	31
11	Sodium dilaurylaminecystine	Anionic	24	0.02	33.8
12	Soidium-N-dilauroylsarcosinate	Anionic	24	0.95	33.6	32
13	Sodium-1,2-bis-N-dodecanoyl-β-alanine	Anionic	24	0.04	27.0	33
14	N α, Nω-Bis (Nα-lauroylarginine)α, ω-hexyldiamide dihydrochloride salts	Cationic	24	0.28	30.0	8
15	14-6-14	Cationic	28	5.62	42.5	34
16	12-6-12	Cationic	24	1.12	42.5	35
17	Sodium dodecyl sulphate SDS	Anionic	12	8.20	32.5	27

^aR – number of carbon atoms in the aliphatic chain/s.