Chunhui Shen

Synthesis of cyanoethyl konjac glucomannan and its liquid crystalline behavior in an ionic liquid

Cyanoethyl konjac glucomannan (CKGM) products with various degree of substitution (DS) were synthesized, and their chemical structure was characterized by infrared spectroscopy and 1H and 13C NMR spectroscopy. Direct evidence of the formation of liquid crystalline phase of cyanoethyl KGM (DS = 2.10) solution in 1-allyl-3-methylimidazolium chloride (AMIMCl), a room temperature ionic liquid, was confirmed by using polarized optical microscopy (POM). The mesophase and anisotropic phase of cyanoethyl KGM solutions and the phase transition boundaries were investigated by steady shear and dynamic sweep measurements. The crystalline state of the cyanoethyl KGM powder and solution were studied by wide X-ray diffraction.

Synthesis and characterisation of chitosan–nitrogen polyphosphonic acid poly(organosiloxane) high temperature proton exchange membranes for fuel cells

One kind of acid–base high temperature proton exchange membrane was synthesised from chitosan (CS), 3-aminopropyltriethoxysilane (APTES) and amino trimethylene phosphonic acid (ATMP) by sol–gel process. In order to prevent phosphonic acid from leaching out, ATMP was introduced as proton conductor as well as cross-linker. Fourier transform infrared suggests that the Si–OC2H5 in APTES appears as a hydrolysis–polycondensation yielding Si–O–Si network, and the introduction of ATMP leads to the protonation of the amino group. These membranes are thermally stable up to ∼180°C and show excellent oxidative stability. In addition, the proton conductivity of CS/APTES/ATMP membranes increases with increasing temperature, reaching the value of 0·0578 S cm− 1 at 140°C under normally anhydrous condition, which indicates that the acid–base pair and hydrogen bond network in CS/APTES/ATMP membranes are favourable to proton transfer.

Preparation of cationic konjac glucomannan in NaOH/urea aqueous solution

Cationic derivatives of konjac glucomannan (KGM) were homogeneously synthesized by reacting KGM with 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC) in NaOH/urea aqueous solutions. The derivatives were characterized by FT-IR, 1H NMR, elemental analysis, thermogravimetric analysis and zeta potential analysis. The results showed that the degree of substitution (DS) of the CKGM with the value of 0.15-0.46 could be obtained by changing the molar ratio between KGM and CHPTAC. The TG/DTG revealed that the thermal stability of KGM after cationization was lower than that of raw KGM. Among a wide range of pH value, the zeta potential in CKGM solution was shown with positive charges. The flocculation capacity of the CKGM was assessed through Kaolin suspension using the light transmission test. The results exhibited that the CKGM had excellent flocculation performance and could be used as an emerging flocculant agent in the wastewater treatment.