Preparation Of Lyotropic Chiral Nematic Liquid Crystals And Composites Of Tunicate Cellulose

In recent times there has been a drive to utilize non-oil-based polymers. Cellulose,which can be extracted from a broad range of plants and animals, is an almostinexhaustible raw material and a key source of sustainable materials. Tunicates, afamily of sea animals, are the only animals known to produce cellulose. Tunicatecellulose (TC) with highly crystalline cellulose Iβoffer great opportunities in the fieldof edible and packaging films as well as biodegradable materials.In this thesis, TC was abstracted from the tunicate mantles. Suspens ions ofcellulose nanocrystals (CNs) and lyotropic chiral nematic liquid crystals (N*-LCs)were prepared by sulfuric acid hydrolysis of TC and cotton cellulose (CC),respectively. The N*-LCs were treated by800W high-power sonication for regulatingthe pitch of N*-LCs. The N*-LCs and films of CNs were characterized by Fouriertransform infrared spectrometer (FT-IR), X-ray diffractometer (XRD), polarizingoptical microscope (POM), scanning electron microscope (SEM), transmissionelectron microscope (TEM), ultraviolet-visible-near infrared reflectance spectrometer(UV-Vis-NIR) and conductivity meter. It was found that the TC consists mostly Iβphase. The tunicate cellulose nanocrystals (T-CNs) were20-30nm in width and0.5-4μm in lLngth. The T-CNs suspension shows different texture in differentconcentration, when the concentration is4wt%the finger-print texture exhibit and thepitch is about15μm. And after evaporation, some transparent films which canselectively reflect45%of the near infrared light were prepared. The high-power sonication could decrease the size of the T-CNs and obtain a well-dispersed colloidalsuspension, while the N*-LCs become a mono-domain finger-print texture and thepitch increases. The N*-LCs of C-CNs and T-CNs with different ratios were mixedand the pitch of the mixture changed by varying the mixing ratio.In this thesis, the C-CNs suspensions were treated by high-power sonication tostudy the mechanism how it effects the pitch of the N*-LCs. The N*-LCs and films ofcotton cellulose nanocrystals (C-CNs) were characterized by POM, SEM, UV-Vis,XRD and conductivity test. It was found that the pitch increases with the increase ofultrasonic energy. After evaporation, some colorful films were prepared. The color ofthe films changed from blue-violet to red with increasing energy inputs. Thehigh-power sonication didn’t change the size and the crystal structure of the C-CNs. Itwas found that the C-CNs suspension conductivity increases with sonication.Polyaniline (PANI) and polypyrrole (PPy) has excellent electrical conductivity,but not easily processed into products. In this paper, we successfully prepared thePANI/T-CNs and PPy/T-CNs nanocomposites via in situ oxidative chemicalpolymerization by using ammonium persulfate (APS) as oxidants and T-CNs as amatrix. The structure of nanocomposites was characterized by using POM, FT-IR,SEM and TEM. The electrical conductivity of the films was characterized by usingstandard four-probe technique. It was found that PANI and PPy nanoparticles form acontinuous coating covered on the surface of T-CNs. The diameter of the nanoparticlesincreased from10to100nm with the increasing of monomer amount. Highly flexiblepaper-like films showed high electrical conductivity of10-4~10-1S·cm-1and goodmechanical properties, which may find important technological applications such assensors, lightweight energy storage systems and so on.