Synthesis And Characterization Of Carboxymethyl Cellulose-based Conductive Hydrogel

In recent years, conductive hydrogels are subjected extensive attention of the people for their applications in sensor, capacitor, tissue engineering and so on. Come so far, the problem is that the mechanical property of these materials is so poor that they cannot satisfy the needs of practical application. The commonly used method to solve the problem is to make composite which contained conductive polymers and conventional hydrogels. Simultaneously, the resulted composite possessed of good mechanical performance and conductivity. On the other hand, because of the focus issue about energy and environmental, cellulose and its derivative which are rich in storage are widely used to study novel factional materials, such as hydrogels based on cellulose. Due to the excellent biocompatibility and mechanical property, cellulose hydrogels combined with conductive macromolecule has been one of research hotspots of conductive hydrogels.In this work, polyaniline（PAn） was combined with hydrogels based on carboxymethyl cellulose（CMC） via the conventional method of interpenetrating polymer network（IPN） and CMC/PAn conductive composite hydrogels was prepared. The molecule structure, microtopography, thermal stability and swelling ratio were studied by the measurements of infrared spectroscopy, scanning electro microscope, thermogravimetric analysis and swelling experiment. The focus was effects of various factors on conductivity and mechanical property of hydrogels.1、CMC/PAn conductive composite hydrogel was prepared by the method of IPN with glycerol diglycidyl ether（GDE） as crosslinking agent. The composite was examined by 13C-NMR, FT-IR SEM and XRD; Results showed that PAn had been inserted into CMC hydrogel successfully. The composite hydrogels containing different concentration of CMC presented a similar swelling kinetic behavior and a relatively high swelling rate. It was found that the composite hydrogel got the best mechanical property and conductivity when the CMC concentration was 7% and the mole ratio of GDE to anhydro glucose unit（AGU） was 5:8. By doping with sodium benzenesulfonate（BSNa）, the conductivity was up to 6.31×10-3 S/cm.2、Based on the results of the second chapter, PEG was selected to be the enhancer of CMC/PAn hydrogels; PA、BSNa and TsONa were selected to be dopants of PAn. These chemicals were used to improve the mechanical property and conductivity of composite hydrogels. The results showed that the introduction of PEG600 enhanced the mechanical strength of composite hydrogel greatly. The conductivity increased first and then decreased with the increasing of the concentration of dopants, the hydrogel doped with BSNa got the best conductivity, 1.22×10-2 S/cm. The results of FT-IR、SEM and TGA indicated that dopants had a great influence on the morphology of composite hydrogels, they also raised the thermo stability of hydrogels.3、CMC/PAn conductive composite gel beads were preparead by the method of physical crosslinking through one step with FeCl₃ as crosslinker and oxidant. The molecular structure and morphology were characterized by FT-IR 、 SEM and EDS. The water loss and conductivity of gel beads were controlled by the concentration of FeCl₃、CMC and BSNa. When the concentrations were 4.5%、0.5mol/L and 0.4mol/L, respectively, the gel bead had the best conductivity: 5.2×10-3S/cm. The composite gel beads exhibited a stable adsorption to methyl blue（MB） although in different concentration of MB solution and the adsorption rate remained at around 30%⁵0%; the adsorption amount got the best of 17.58mg/g when the initial concentration was at the maximum of 14mg/L.