We have synthesized two amphiphilic cholesteryl dimers, bis(cholesterylsuccinamidoethyl) ether [(NHSCE)₂] and bis(cholesterylphthalamidopropyl) ether [(NHPCE)₂]. They form stable Langmuir monolayer films at air-water interface. (NHSCE)₂ exhibits only liquid condensed phase, whereas (NHPCE)₂ exhibits both liquid expanded and liquid condensed phases. The collapse phenomenon of a Langmuir monolayer has relevance to biological processes like control of surface tension in lung alveolar and so on. Our studies show that the collapse pressure (π_c) of (NHPCE)₂ Langmuir monolayer is invariant with the strain rate of compression and temperature. Interestingly, the π_c of (NHSCE)₂ Langmuir monolayer depends on the strain rate of compression and temperature. A power law relation is used for analysis of the strain rate dependence of π_c. On varying the temperature, initially we find an increase in π_c with increase in temperature, a behavior known as alpha (α) flow. On further increase in temperature, we find decrease in π_c, a behavior known as kappa (κ) flow. The α- flow is very unusual and has not been reported in literature for dimers. An analogy is drawn between the observed α- flow in (NHSCE)₂ dimer and the yield strength anomaly reported for alloys.

我们已经合成了两种两亲性胆固醇二聚体，双（胆固醇琥珀酰胺乙基）醚 [(NHSCE) ₂ ] 和双（胆固醇邻苯二甲酰胺丙基）醚 [(NHPCE) ₂ ]。它们在空气-水界面形成稳定的朗缪尔单层膜。(NHSCE) ₂仅表现出液体凝聚相，而(NHPCE) ₂表现出液体膨胀相和液体凝聚相。Langmuir 单层的塌陷现象与生物过程有关，如控制肺泡表面张力等。我们的研究表明，(NHPCE) ₂ Langmuir 单层的坍塌压力 (π _c )与压缩应变率和温度无关。有趣的是，π _c(NHSCE) ₂ Langmuir 单层取决于压缩应变率和温度。幂律关系用于分析 π _c的应变率相关性。在改变温度时，最初我们发现 π _c随着温度的升高而增加，这种行为称为 alpha (α) 流。随着温度的进一步升高，我们发现 π _c降低，这种行为称为 kappa (κ) 流。α-流是非常不寻常的，并且在二聚体的文献中没有报道。在观察到的 (NHSCE) ₂二聚体中的α-流和合金报告的屈服强度异常之间进行类比。