Sıvı kristallerde yüzey etkilerinin moleküler dinamik simülasyon ile incelenmesi
Yükleniyor...
Tarih
2016
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Ege Üniversitesi, Fen Bilimleri Enstitüsü
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Bu tezde, alkan ve alkol molekülleri ile kaplanmış grafen yüzeyler üzerinde nematik tek tabaka pentil siyanobifenil (5CB) ve pentiloksi siyanobifenil (5OCB) sıvı kristal (SK) bileşikler, moleküler dinamik (MD) simülasyon yöntemi ile incelenmiştir. Pentan (C5), dodekan (C12), hekzadekan (C16), pentanol (C5OH) ve dodekanol (C12OH) yönlendirici yüzey molekülü olarak seçilmiştir. Yüzey molekülleri ile kaplı grafen üzerindeki tek tabaka SK moleküllerinin yayınım ve yapısal özelliklerini, yönelimlerini incelemek için SK moleküllerinin öteleme difüzyon katsayıları, radyal dağılım fonksiyonları ve eğim açıları hesaplandı. Yüzey molekülleri ve SK molekülleri arasındaki arayüz bölgesini karakterize etmek için bu moleküllerin sayıca yoğunluk profil hesapları yapıldı. Farklı C atom sayılı yüzey molekülleri kullanılarak zincir uzunluk etkisi, yüzey molekül sayısı değiştirilerek kaplama yoğunluk etkisi ve simülasyon hücresi genişletilerek sistem büyüklük etkisi incelendi. 5CB ve 5OCB molekülleri üzerine polar hidroksil fonksiyonel grubunun etkisini anlamak için, yüzey molekülü olarak alkoller kullanıldı. C5/C16 ve C5OH/C12OH karışım yüzey kaplamalı sistemlerin simülasyonları yapıldı ve sonuçlar tartışıldı. Elde edilen sonuçlar önceki çalışmaların sonuçları ile kıyaslandı.
In this thesis, the nematic monolayer pentyl cyanobiphenyl (5CB) and pentyloxy cyanobiphenyl (5OCB) liquid crystal (LC) compounds on graphene surfaces covered by alkane and alcohol molecules have been investigated by molecular dynamics simulations. Pentane (C5), dodecane (C12), hexadecane (C16), pentanol (C5OH) and dodecanol (C12OH) molecules were chosen as orienting surface molecules. To investigate the transport and structural properties and the alignment of the monolayer LCs at the graphene covered by the surface molecules, the translational diffusion coefficients, the radial distribution functions and the tilt angle of LC molecules were calculated. To characterise the interface region between the surface and LC molecules, the calculation of the number density profiles of these molecules were found. The effect of chain length by using the surface molecules with different C atom numbers, the effect of coverage density by changing the surface molecule numbers and the effect of system size by enlarging the simulation cell were investigated. In order to understand the effect of the polar hydroxyl functional group on the 5CB and 5OCB molecules, the alcohols were chosen as surface molecules. The simulations of the systems with the C5/C16 ve C5OH/C12OH mixed surface coverage were performed and the results were discussed. The obtained results were compared with the results of the previous studies.
In this thesis, the nematic monolayer pentyl cyanobiphenyl (5CB) and pentyloxy cyanobiphenyl (5OCB) liquid crystal (LC) compounds on graphene surfaces covered by alkane and alcohol molecules have been investigated by molecular dynamics simulations. Pentane (C5), dodecane (C12), hexadecane (C16), pentanol (C5OH) and dodecanol (C12OH) molecules were chosen as orienting surface molecules. To investigate the transport and structural properties and the alignment of the monolayer LCs at the graphene covered by the surface molecules, the translational diffusion coefficients, the radial distribution functions and the tilt angle of LC molecules were calculated. To characterise the interface region between the surface and LC molecules, the calculation of the number density profiles of these molecules were found. The effect of chain length by using the surface molecules with different C atom numbers, the effect of coverage density by changing the surface molecule numbers and the effect of system size by enlarging the simulation cell were investigated. In order to understand the effect of the polar hydroxyl functional group on the 5CB and 5OCB molecules, the alcohols were chosen as surface molecules. The simulations of the systems with the C5/C16 ve C5OH/C12OH mixed surface coverage were performed and the results were discussed. The obtained results were compared with the results of the previous studies.
Açıklama
Anahtar Kelimeler
Sıvı Kristaller, Molüküler Dinamik Simülasyon, Yüzey Etkisi, Sıvı Kristallerin Yönelimi, Liquid Crystals, Molecular Dynamics Simulation, Surface Effect, Alignment Of Liquid Crystals.
