Yoshimura Tomokazu, Saito Masanori, Esumi Kunio
Research Group of Chemistry, Division of Natural Science, Nara Women's University, Nara, Japan.
J Oleo Sci. 2013;62(4):213-21. doi: 10.5650/jos.62.213.
Tadpole-type amphiphilic dendrimers consisting of an alkyl chain, a quaternary ammonium bromide (qb) and a poly(amidoamine) dendron (den) (CnqbdenGm, where n represents an alkyl chain with a length of 10,14, or 18 carbons; m is the generation number G of dendron taking the value -0.5, 0.5, or 1.5) were synthesized using N, N-dimethylethylenediamine as a central scaffold. Electrical conductivity, surface tension, pyrene fluorescence, and dynamic light scattering measurements were used to characterize the properties of the dendrimers. In addition, the effect of the alkyl chain length and the generation number of a dendron on these properties was evaluated through a comparison with those of the corresponding previously reported amphiphilic dendrimers with lactobionamide sugar terminal groups (CnqbdenGmLac) and conventional cationic monomeric surfactants (CnTAB). Both critical micelle concentration (cmc) and surface tension (except for C18 series) were lower than those of CnqbdenGmLac and CnTAB with the same alkyl chain length, indicating that the synthesized amphiphilic dendrimers have an excellent micelle-forming ability in solution and high adsorption ability at the air/water interface, in spite of the large bulky dendron structure. When the alkyl chain length and the generation number of the amphiphilic dendrimers were increased, the surface tension became high because of the curved long alkyl chain and the bulky structure of dendron. Further, CnqbdenGm formed micelles with a small size in solution, and the micelles of CnqbdenG(-0.5) had almost a constant size despite the changes in the concentration, while those of CnqbdenG0.5 and CnqbdenG1.5 became smaller with increasing concentration. The difference in the behavior results from the difference in the number of amide groups in the low- and high-generation dendrons.
以N，N-二甲基乙二胺为中心骨架合成了由烷基链、溴化季铵（qb）和聚（酰胺胺）树枝状分子（den）组成的蝌蚪型两亲性树枝状大分子（CnqbdenGm，其中n代表含10、14或18个碳的烷基链；m是树枝状分子的代数G，取值为-0.5、0.5或1.5）。通过电导率、表面张力、芘荧光和动态光散射测量来表征树枝状大分子的性质。此外，通过与相应的先前报道的具有乳糖二酰胺糖端基的两亲性树枝状大分子（CnqbdenGmLac）和传统阳离子单体表面活性剂（CnTAB）进行比较，评估了烷基链长度和树枝状分子代数对这些性质的影响。具有相同烷基链长度的两亲性树枝状大分子的临界胶束浓度（cmc）和表面张力（C18系列除外）均低于CnqbdenGmLac和CnTAB，这表明尽管树枝状大分子结构庞大，但合成的两亲性树枝状大分子在溶液中具有优异的胶束形成能力，在空气/水界面具有高吸附能力。当两亲性树枝状大分子的烷基链长度和代数增加时，由于弯曲的长烷基链和树枝状大分子的庞大结构，表面张力升高。此外，CnqbdenGm在溶液中形成尺寸较小的胶束，CnqbdenG(-0.5)的胶束尺寸几乎不随浓度变化而恒定，而CnqbdenG0.5和CnqbdenG1.5的胶束尺寸随浓度增加而减小。这种行为差异源于低代数和高代数树枝状大分子中酰胺基团数量的差异。
