Bazı sıvı kristal-sıvı arayüzeylerinin moleküler dinamik simülasyon yöntemi ile incelenmesi
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Dosyalar
Tarih
2016
Yazarlar
Dergi Başlığı
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Yayıncı
Ege Üniversitesi, Fen Bilimleri Enstitüsü
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
4-n-alkil-4'-siyanobifenil (nCB) serisinin iki üyesinin (n=5 ve 8) hava-su arayüzeyindeki adsorbsiyonu detaylı atomistik moleküler dinamik (MD) simülasyonlar ile incelenmiştir. Her bir mezojen için farklı yüzey konsantrasyonları içeren dört sistem seçilmiştir. Su molekülleri, sıvı kristal moleküller ve sıvı kristaldeki belirli atom tipleri için arayüzey normali boyunca kütlece ve sayıca yoğunluk profilleri verilmiştir. Siyano grupları arayüzeyin su tarafına, metil grupları ise sudan uzak tarafa doğru yönelme eğilimindedir. Yoğunluk profilleri sırası ile hiperbolik tanjant ve Gaussian formundaki fonksiyonlara fit edilerek arayüzeyin ve adsorbe edilen tabakanın kalınlıkları tahminlenmiştir. Hesaplanan P2, P4 ve P6 düzen parametreleri, mezojenlerin arayüzeyde daha organize yapıları nedeni ile hacimsel faz için daha önce rapor edilmiş olan deneysel verilerden epeyce büyüktür. Farklı atomlar arasındaki radyal dağılım fonksiyonları, self-difüzyon katsayıları, tek tabaka normaline göre eğim açıları ve muhtelif büyüklüklerin histogramları hesaplanmıştır.
Adsorptions of two members of 4-n-alkyl-4'-cyanobiphenyls (nCB) with n=5 and 8 at the air-water interface were studied by detailed atomistic molecular dynamics (MD) simulations. For each mesogen, four systems containing different surface coverages were selected. The mass and number density profiles of the water and liquid crystal molecules and of several different atom types along the interface normal axis were presented. At the interface, the cyano groups tend to point toward the waterside of the interface, with the methyl groups pointing farther away from water. The thicknesses of the interface and the adsorbed layer were estimated by fitting the density profiles into a hyperbolic tangential and Gaussian functional form, respectively. The calculated orientational order parameters P2, P4 and P6 were generally much greater than the experimental data previously reported for the bulk phase, because of more organized structure of mesogens at the interface. The radial distribution function among different atoms, self-diffusion coefficients, tilt angles with respect to the monolayer normal and the histograms of the various quantities were calculated.
Adsorptions of two members of 4-n-alkyl-4'-cyanobiphenyls (nCB) with n=5 and 8 at the air-water interface were studied by detailed atomistic molecular dynamics (MD) simulations. For each mesogen, four systems containing different surface coverages were selected. The mass and number density profiles of the water and liquid crystal molecules and of several different atom types along the interface normal axis were presented. At the interface, the cyano groups tend to point toward the waterside of the interface, with the methyl groups pointing farther away from water. The thicknesses of the interface and the adsorbed layer were estimated by fitting the density profiles into a hyperbolic tangential and Gaussian functional form, respectively. The calculated orientational order parameters P2, P4 and P6 were generally much greater than the experimental data previously reported for the bulk phase, because of more organized structure of mesogens at the interface. The radial distribution function among different atoms, self-diffusion coefficients, tilt angles with respect to the monolayer normal and the histograms of the various quantities were calculated.
Açıklama
Anahtar Kelimeler
Sıvı Kristal, Hava-Su Arayüzeyi, Moleküler Dinamik, Yoğunluk Profilleri, Düzen Parametreleri, Eğim Açıları, Radyal Dağılım Fonksiyonu, Self-Difüzyon Katsayıları, Liquid Crystal, Air-Water Interface, Molecular Dynamics, Density Profiles, Order Parameters, Tilt Angles, Radial Distribution Function, Self-Diffusion Coefficients
