Light scattering from semidilute solutions of nonionic surfactants (C12E5 and C12E8) and the scaling law

Abstract

Static and dynamic light scattering have been measured on D20 solutions of nonionic surfactant C12E5 in the concentration range 3-300 g dm"3 at different temperatures. The results for the semidilute solutions at higher temperatures can be explained by the scaling theory for entangled solutions of flexible polymers which exhibit phase separations. Temperature dependences of the light scattering data suggest that the "0 temperature" exists at 27-30 °C (the lower critical consolution point is 30.5 °C), which is in approximate agreement with results of our previous studies for dilute solutions. Relation to the existence of liquid crystal phases is also discussed. Measurements of dynamic light scattering have been made on D20 solutions of C,2Ej also. The data do not follow the scaling law even at higher temperatures, which may come from the fact that C12E8 micelles are much smaller than C12E5 micelles.(44) The concept of the 9 temperature has been introduced into micellar solutions already by Fujimatsu et al.. However, the method employed in the present study is completely different from theirs. See:

Wormlike Micelles of Polyoxyethylene Dodecyl C12Ej and Heptaoxyethylene Alkyl CiE7 Ethers. Hydrophobic and Hydrophilic Chain Length Dependence of the Micellar Characteristics

“…11-24 Brown and his coworkers 11-13 studied solution properties of C 12 E 5 , C 12 E 6 , C 12 E 7 , and C 12 E 8 micelles by SLS, DLS, and pulsed field gradient NMR measurements. Similar studies were performed for C 12 E 5 , C 12 E 6 , and C 12 E 8 micellar solutions by Kato et al 16,17 They showed that the C i E j micelles grew in size with raising temperature and increasing surfactant concentration, and that intermicellar thermodynamic and hydrodynamic interactions strongly increase with concentration. Bernheim-Groswasser et al…”

“…[11][12][13][14][15][16][17][18][19][20][21][22][23][24] Brown and his coworkers [11][12][13] studied solution properties of C 12 E 5 , C 12 E 6 , C 12 E 7 , and C 12 E 8 micelles by SLS, DLS, and pulsed field gradient NMR measurements. Similar studies were performed for C 12 E 5 , C 12 E 6 , and C 12 E 8 micellar solutions by Kato et al 16,17 They showed that the C i E j micelles grew in size with raising temperature and increasing surfactant concentration, and that intermicellar thermodynamic and hydrodynamic interactions strongly increase with concentration. Bernheim-Groswasser et al 24 realized by cryo-TEM observations that in the growth of the C 12 E 5 micelles thread-like or polymer-like micelles were evolved in the solutions examined, especially to the greater length in the vicinity of the lower consolute point.…”

Wormlike Micelles of Binary Polyoxyethylene Alkyl Ether Mixtures C10E6 + C14E6 and C14E8 + C14E6

“…8 Dynamic Light Scattering DLS measurements were carried out to determine the translational diffusion coefficient D for the micelles by the use of the same apparatus and light source as used in the SLS studies described above. All the test solutions studied are the same as those used in the SLS studies.…”

Solubilization of Polyelectrolytic Hairy-Rod Polyfluorene in Aqueous Solutions of Nonionic Surfactant

“…20 Oxyethylene glycol-monoethers (C i E j ) 21,22 are archetypical surfactants widely used in fundamental phase studies of microemulsions, [23][24][25][26][27] block-co-polymers, 28 and micelles. 29,30 The phase behavior of pentaethylene glycol monododecyl ether (ndodecyl pentaoxyethylene glycol ether) (C 12 E 5 ) 31,32 is particularly well-known: Pure C 12 E 5 forms cylindrical micelles but the oil-swollen C 12 E 5 micelles are wormlike with a rather high flexibility and cannot be described as rigid rods. 33,30 Several C i E j s can be used to solubilize selected PPPs 34,35 and PFs.…”