Molecular conformation of nonionic surfactants in the solid state. A Raman spectroscopic study of a homologous series of .alpha.-n-alkyl-.omega.-hydroxyoligo(oxyethylenes)

Phase Behavior of Aqueous Mixtures of Some Polyethylene Glycol Decyl Ethers Revealed by DSC and FT-IR Measurements

“…There might be a possibility that this deviation is attributed to the difference in the conformational structure of the POE chain assumed in a solid phase between C 10 E 4 and other C 10 E m compounds with longer POE chains. Matsuura et al (26,27) have carried out detailed investigations concerning the conformational aspects of C n E m in a solid phase, applying Raman spectroscopy for a number of surfactant species with various m and n, and have reported that with the increase in the POE chain length, the conformational change of the POE chain from a highly extended all-trans form to a gauche-containing helical form takes place at m ϭ 3-4, depending on the alkyl chain length. For an homologous series of C 10 E m , however, this conformational transformation occurs between m ϭ 3 and m ϭ 4, and hence, all the POE chains in C 10 E m compounds used in our studies (m ϭ 4-8) are helical structure in a solid phase (27).…”

“…Matsuura et al (26,27) have carried out detailed investigations concerning the conformational aspects of C n E m in a solid phase, applying Raman spectroscopy for a number of surfactant species with various m and n, and have reported that with the increase in the POE chain length, the conformational change of the POE chain from a highly extended all-trans form to a gauche-containing helical form takes place at m ϭ 3-4, depending on the alkyl chain length. For an homologous series of C 10 E m , however, this conformational transformation occurs between m ϭ 3 and m ϭ 4, and hence, all the POE chains in C 10 E m compounds used in our studies (m ϭ 4-8) are helical structure in a solid phase (27). The smaller hydration number for C 10 E 4 may suggest that the affinity of the POE chain for water molecule is reduced when the POE chain becomes too short, although the mechanism is not clear.…”

Conformational Analysis of Nonionic Surfactants in Water by a Selective Monodeuteration Method. C−D Stretching Infrared Spectroscopy of α-Monodeuterododecyl-ω-hydroxytris(oxyethylene)s

“…By using these marker bands, detailed conformational analysis is possible even for complex systems. We have studied by Raman spectroscopy the molecular conformation of a series of C n E m surfactants ( n = 1−16 and m = 1−8) in the solid state and have clarified the relation between the conformation and the chain length. − Vibrational spectroscopy has been applied extensively to aqueous solutions of C n E m and other related surfactants. − In most of these studies, the molecular structure has been discussed in relation to the phase transitions in the surfactant−water systems. The phase and conformational transitions in lipids and biomembranes have also been studied by vibrational spectroscopy…”

Surface‐Enhanced Raman Spectroscopy of Tribochemically Formed Boundary Films of Refined and Unrefined Canola Oils

“…No peaks were observed at 2,850 and 2,885 cm -1 which are usually assigned to the symmetric and asymmetric stretching modes of the CH 2 group [32][33][34][35]. The peak at 760 cm -1 can be assigned to either the terminal CH 3 rocking mode [36,37] or C-H out of plane deformation [38]. It is interesting to note that there is a lack of contribution from the stretching vibrations of the CH 2 groups since the population of CH 2 monomers clearly outnumbers the terminal CH 3 group for long chain fatty acids.…”