Monte carlo simulation on the role of water in the trilayer transition of amphiphilic molecules at the air-water interface = 공기-물 계면에서 양친성 분자의 단분자층에서 세분자층으로의 상변화에 끼치는 물의 영향에 관한 몬테 카를로 시뮬레이션

It is known that most of amphiphilc molecules show a phase transition from monolayer to trilayer, not bilayer, when they are compressed at an air-water interface. However, the reason why they form a trilayer is not thoroughly investigated. In this Monte Carlo simulation study, we suggest that a monolayer-trilayer phase transition is due to water molecules accompanied by the amphiphilic molecule in the upper part of the layer. An amphiphilic molecule was modeled as consisting of two parts, hydrophilic and hydrophobic parts, and the amount of water accompanied by the amphiphilic molecule was assumed to be exponentially decaying with the height. Lennard-Jones interaction was used as interactions between molecules. From the simulation results, it was found that the odd-numbered layer is stable because of the hydrophobic effect and surface tension of the water. Further simulations show that as more water is accompanied by the molecules in the higher floor of the layer the odd-numbered layer becomes more stable and so the internal ordering of molecules does. The calculated π-A isotherm is consistent with previous experimental results and suggests that the transition is first-order.
Advisors
Kim, Mahn-Wonresearcher김만원researcher
Publisher
한국과학기술원
Issue Date
2004
Identifier
237786/325007  / 020023314
Language
eng
Description

학위논문(석사) - 한국과학기술원 : 물리학과, 2004.2, [ 34 p. ]

Keywords

phaser transition; 상전이; 몬테 카를로 시뮬레이션; amphiphilic molecules; water; Monte Carlo simulation; 물; 양친성 분자

URI
http://hdl.handle.net/10203/48654
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=237786&flag=t
Appears in Collection
PH-Theses_Master(석사논문)
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