Soft Nanoscience Letters, 2013, 3, 11-13 doi:10.4236/snl.2013.31003 Published Online January 2013 (http://www.scirp.org/journal/snl) 11 Composite Materials Containing Perfluorinated and Siloxane Units for Vertical Alignment of Liquid Crystals * Rasha Ata Alla 1 , Gurumurthy Hegde 1,2 , Lachezar Komitov 1# , Andrea Morelli 3 , Emo Chiellini 3 , Giancarlo Galli 3 1 Liquid Crystal Group, Department of Physics, University of Gothenburg, Gothenburg, Sweden; 2 Faculty of Industrial Sciences and Technology, University Malaysia Pahang, Kuantan, Malaysia; 3 Department of Chemistry and Industrial Chemistry, University of Pisa, Pisa, Italy. Email: # komitov@physics.gu.se, murthyhegde@gmail.com Received November 16 th , 2012; revised December 20 th , 2012; accepted December 31 st , 2012 ABSTRACT Here we report on the study of vertical alignment of a nematic liquid crystal due to the segregation between perfluori- nated and the polysiloxane groups of a multi-component composite alignment material. The measured surface anchor- ing energy was found to depend on the relative amount of polysiloxane matrix in the composite material. These kind of self-assembly will reduce the preparation time for display by eliminating few steps. Keywords: VA; Nematic; Self Assembling; Vertical Alignment; Anchoring Energy 1. Introduction Liquid Crystal alignment is the subject of interest ever since it is used in the display industry. Many materials capable to align liquid crystals (LC) have been discov- ered lately and used for preparation of alignment layers in liquid crystal displays (LCDs). Majority of these ma- terials are devoted to vertical alignment (VA) since this kind of alignment offers some advantages such as high contrast ratio and no need for mechanical rubbing. The most important physical mechanism behind VA is the low surface energy of the alignment surface [1]. How- ever, depending on the alignment material structure, the LC molecules may interact sterically with the molecules of the alignment material. As shown in ref. [2], the steric interactions are playing an important role for the quality of VA and the magnitude of the anchoring strength. Con- siderable attention has been consecrated to self-assem- bled materials, among all other materials which promote VA, because of their wide applications in advanced ma- terials such as optoelectronic materials since they have the ability for self-assembling into regular manner with Nano sized structures [3]. Perfluorinated groups are widely used for many applications as self-assembled materials since they show very interesting properties such as low surface energy and high chemical and ther- mal stability [3-7]. It has been observed that the align- ment layers with low surface energy, such as the fluo- rine-rich films, usually gives rise to VA since the surface energy of the alignment layer is less than the surface en- ergy of the liquid crystal [8,9]. In general fluorination process enhances the rigidity of the molecules and in- creases the stability by reinforcing the microphase seg- regation with the polar groups due to the high electro- negativity of the fluorine atoms [3,4,10]. In this work perfluorinated groups, regarding their properties, were used as a part of mixture to perform an alignment mate- rial as a feasible method to achieve a uniform good VA to fulfill LCDs development requirements. 2. Experimental Here we report on the study of VA of a nematic liquid crystal promoted by multi-component composite align- ment materials. For our experimental study, conventional sandwich cells were prepared. The cells’ substrates were pre-coated with transparent conductive layer ITO with alignment layer deposited on top of it. A photopolymerized thin film, prepared from a mul- ti-component composite material with perfluorinated and polysiloxane groups as major components, was used as alignment layer. The chemical structures of the compo- nents of the composite alignment materials, which were studied in this work, are shown in Figure 1. The relative ratio of these components in the compos- ite material blends are given in Table 1. * GH is thankful to the Universiti Malaysia Pahant for financial support in the form of RDU grant RDU120367. # Corresponding author. Perfluorinated siloxane polymers have attracted our Copyright © 2013 SciRes. SNL