The effect of liquid crystalline graphene oxide compared with non-liquid crystalline graphene oxide on the rheological properties of polyacrylonitrile solution

In this article, polyacrylonitrile (PAN) and two kinds of graphene oxide (GO) with different structural properties are blended in dimethyl sulfoxide (DMSO) according to a certain ratio to prepare stable-spinning solution. One kind of GO is purchased, and we call it GO1. The other is a kind of self-made GO with liquid crystal property in solution, which is called GO2. The effects of two kinds of GO on the rheological properties of PAN/GO spinning solution (15 wt%) were studied. The results show that the viscous activation energy of the liquid crystal GO2/PAN blend solution is significantly higher than that of the nonliquid crystal GO1/PAN blend solution. Moreover, the liquid crystal system is more obviously affected by temperature. The structural viscosity index of the liquid crystalline GO2/PAN solution is obviously lower than that of the GO1/PAN solution. It indicates that the existence of liquid crystallinity is beneficial to the spinning of the solution. In the low-frequency region, the addition of GO1 makes the solution more elastic, and the addition of GO2 makes the solution more viscous.

NEW MACROMOLECULAR STRUCTURES SYNTHESIS AND CHARACTERIZATION

Liquid crystals are unique in their properties and use and has an essential role in the area of technological applications such as electrical, optical, displayers, temperature maps, and switching materials. This study aimed to synthesize hexaethynylbenzene derivatives starting from 1,3,5-trichlorobenzene benzene as a central core substituted with three aromatic ring and three armed of 2-chloro-4,6-bis((3,7-dimethyloct-6-en-1-yl) oxy)-1,3,5-triazine. These molecules are formed by the covalent linking of three arms symmetrically to a central core which may be attached to the central core through flexible, semi-flexible or rigid linkers. The substitution occured at the acetylenic periphery on the central benzene ring and was achieved efficiently by Sonogashira coupling. The six-armed compounds based on the benzene core was mixed with the complementary 4-dodecyloxybenzoic acid 1:1 ratio, which already possessed liquid crystal property to increase the formation of these resulting in an organic salt. The obtained organic salts were investigated for their liquid crystal behaviour by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). All the intermediate and final compounds were confirmed by spectroscopic techniques (1H NMR, 13C NMR, and mass spectrometry).

Six-armed Structures Based on Benzene Ring, Synthesis and Characterization Via Sonogashira Coupling

A new six-armed compounds consist of benzene ring as a central core substituted with aromatic ring and three rod-like armed of 2-chloro-4,6-bis(dodecyloxy)-1,3,5-triazine as the peripheral arms unit which obtained by sequential nucleophilic substitution of chlorine atoms in cyanuric chloride. The substitution took place at the acetylenic periphery on the central benzene ring by Sonogashira coupling. Equimolar mixtures of the six-armed compounds based on the benzene core with the complementary 4-dodecyloxybenzoic acid, which already possessed liquid crystal property, resulted in an organic salt. The organic salts and structures were investigated by differential scanning calorimetry (DSC), and confirmed by spectroscopic methods (1H-NMR, 13C-NMR and Mass spectroscopy)

Structure-Property Relationship of Dodecylbenzenesulfonic Acid Doped Polyaniline

Dodecylbenzenesulfonic acid (DBSA) doped polypanilines (PANIs) were chemically synthesized in different molar ratios of aniline (An) to ammonium persulfate (APS) and An to DBSA. The microstructures of these PANIs were investigated by means of scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier Transform Infrared (FTIR). UV-Vis spectrometer, semiconductor parameter analyzer, ubbelohde viscometer and electrospinning technique were used to characterize the optical, electrical properties, viscosity and solubility of these PANIs. The results show that the molar rations of An to APS and An to DBSA had strong effect on the microstructure, molecular weight, degree of crystallinity, optical property, solubility and conductivity of obtained DBSA doped PANI. With the increase of the molar ratios of An to APS and An to DBSA, the conductivities and molecular weight of DBSA doped PANIs decreased, while the degree of crystallinity and solubility of DBSA doped PANIs increased. The DBSA doped PANI could dissolve in dichloromethane or HFIP and could be fabricated short fibers by electrospinning. Moreover, the solution of DBSA doped PANIs in concentrated sulphuric acid showed liquid crystal property.

Preparation and Thermal Properties Characterization of Cholesterol-Modified Amphiphilic Chitosan

In this article, cholesterol 3-hemisuccinate (CHS) was synthesized through the functionalization of the end group of liquid crystal monomer cholesterol with succinic anhydride. Hydrophobic cholesterol modified low molecular weight chitosan (CS-CH) was synthesized by 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-mediated coupling reaction. Chemical structure, crystalline morphology, and thermal properties of the biological material were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetric (DSC), and polarized light microscopy (POM). The results of POM showed that CHS was a kind of crystalline material with liquid crystal property of cholesterol. DSC showed that the melting point and the crystalline temperature of CHS were 188 °C and 145 °C respectively. DSC also showed that CS-CH was a kind of thermoplastic biological material. The max melting temperature decreased from 120 °C to 110 °C with increasing the weight ratio of EDC/CHS to chitosan.