Nanoparçacıklarla katkılandırılan sıvı kristallerin moleküler dinamik simülasyon yöntemiyle incelenmesi
Küçük Resim Yok
Tarih
2023
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Ege Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Bu tez çalışmasında farklı sayı, biçim ve büyüklüklerdeki altın nanoparçacık (NP) katkılı pentil siyonabifenil (5CB) ve pentiloksi siyanobifenil (5OCB) sıvı kristaller (SK) moleküler dinamik (MD) simülasyon yöntemiyle incelenmiştir. İki farklı yarıçapta küresel NP'ler ve çubuksu NP'ler SK içine farklı sayılarda yerleştirilmiştir. Simülasyonlar, OPLS kuvvet alanı kullanılarak, GROMACS programı ile gerçekleştirilmiştir. MD yörünge bilgilerinden, ikinci ve dördüncü mertebe düzen parametreleri, ?1 dönme viskozite katsayıları, SK moleküllerin yönelimsel dağılım fonksiyonları hesaplanmıştır. Altın NP katkısının SK molekül yapısı üzerindeki etkilerini incelemek için eylemsizlik tensör anizotropisi, iki-eksenlilik, eylemsizlik tensör anizotropi dağılımları ve iki-eksenlilik dağılımları hesaplanmıştır. NP katkısının SK ortamın düzen parametrelerini ve dönme vizkozite katsayılarını azalttığı bulunmuştur. Bu sonuç deneysel çalışmalarla uyumludur. NP katkısının SK moleküllerinin homeotropik dizilimini (moleküllerin z eksenine paralel olduğu dizilim) ve moleküler anizotropiyi azaltırken, iki-eksenliliği arttırdığı bulunmuştur. Bahsedilen değişimler, NP sayısının fazla olduğu özellikle büyük küresel NP'li sistemlerde daha belirgin elde edilmiştir.
In this thesis study, nematic pentyl cyanobiphenyl (5CB) and pentyloxy cyobphenyl (5OCB) liquid crystals (LC) dopped with gold nanoparticles (NP) of different numbers, shapes and sizes have been investigated by molecular dynamics (MD) simulations method. Spherical NPs of two different radii and rod-like NPs are placed in different numbers in the LCs. Simulations were performed with the GROMACS program using the OPLS force field. The second and fourth rank order parameters, the rotational viscosity coefficients ?1 and the the orientational distributions of LC molecules were calculated from the MD trajectories. To study the effects of gold NP addition on LC molecular structure inertia tensor anisotropy, biaxiality, inertia tensor anisotropy distributions and biaxiality distributions were calculated. It was found that NP addition reduces the order parameters and rotational viscosity coefficients of LC medium. This result is in agreement with experimental studies. It has been found that the NP contribution increases biaxiality while decreasing the homeotropic arrangement (arrangement in which molecules are parallel to the z-axis) and molecular anisotropy of LC molecules. The mentioned changes were obtained more clearly in the systems with large spherical NPs, especially where the number of NPs was high.
In this thesis study, nematic pentyl cyanobiphenyl (5CB) and pentyloxy cyobphenyl (5OCB) liquid crystals (LC) dopped with gold nanoparticles (NP) of different numbers, shapes and sizes have been investigated by molecular dynamics (MD) simulations method. Spherical NPs of two different radii and rod-like NPs are placed in different numbers in the LCs. Simulations were performed with the GROMACS program using the OPLS force field. The second and fourth rank order parameters, the rotational viscosity coefficients ?1 and the the orientational distributions of LC molecules were calculated from the MD trajectories. To study the effects of gold NP addition on LC molecular structure inertia tensor anisotropy, biaxiality, inertia tensor anisotropy distributions and biaxiality distributions were calculated. It was found that NP addition reduces the order parameters and rotational viscosity coefficients of LC medium. This result is in agreement with experimental studies. It has been found that the NP contribution increases biaxiality while decreasing the homeotropic arrangement (arrangement in which molecules are parallel to the z-axis) and molecular anisotropy of LC molecules. The mentioned changes were obtained more clearly in the systems with large spherical NPs, especially where the number of NPs was high.
Açıklama
Anahtar Kelimeler
Fizik ve Fizik Mühendisliği, Physics and Physics Engineering
