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Chitosan biguanidine hydrochloride was synthesized by reacting chitosan with dicyandiamide under microwave irradiation. The influence of reaction temperature, reaction solvent and microwave heating time was studied, and optimal conditions were identified. The representative microwave synthesized chitosan biguanidine hydrochloride was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction measurement, taking chitosan as a reference. The solubility pH for the chitosan biguanidine hydrochloride with different substitution degrees was monitored. The antimicrobial activities of chitosan biguanidine hydrochloride were measured by means of the minimal inhibition concentration (MIC). In vitro antimicrobial activity of guanidinylated chitosans with different substitution degrees were evaluated against staphylococcus aureus, bacillus subtilis, escherichia coli and pseudomonas aeruginosa. The results show that the microwave irradiation method can increase the reaction rate by twelve times over the conventional method. Chitosan biguanidine hydrochloride are effective of bacteriostasis, compared with chitosan, guanidinylated chitosan had much better antibacterial activity. The antibacterial activity of chitosan biguanidine hydrochloride derivative enhanced with increasing substitution degrees of guanidinylated chitosan.

The aim of this paper was to reveal the relationship between the interaction energy of benzodifuranone dyes and dyeing performance indices such as dyeing temperature and colour fastness. Dimer models of benzene–benzene, benzodifuranone–benzene, and benzodifuranone–benzodifuranone configuration were set up, and geometry optimisation and interaction energy were calculated using a density functional theory ωB97XD, 6‐311G++ (d, p) basis set. The calculation results showed that the benzodifuranone molecule had better coplanarity. The molecular interaction energy of benzene–benzene, benzodifuranone–benzene, and benzodifuranone–benzodifuranone rings decreased at first, and then increased with growth in the distance between the rings, the lowest energy occurring at a distance of about 3.25–3.75 Å. The dispersion force affected the interaction energy of benzodifuranone–benzene rings most, while both dispersion force and electrostatic force influenced the interaction energy of benzodifuranone–benzodifuranone rings. These calculation and experimental results revealed that a greater energy was needed to destroy the dye–fibre and dye–dye interaction energy of benzodifuranone‐based disperse dyes.

Polyimide fabric, as a high-performance fabric, possesses advantageous properties, such as outstanding thermal stability and chemical resistance, but has poor dyeability. In this paper, polyimide fabric was dyed successfully with disperse dyes by high-temperature and high-pressure dyeing in the presence of a swelling agent and auxiliaries. Under optimal dyeing conditions, it is pretreated with NaOH 6 g l À1 and dyed with disperse dyes 5% o.w.f., NaCl 1 M, benzyl alcohol 60 ml l À1 at 135°C for 45 min to obtain a satisfactory colour yield with good washing fastness and dry rubbing fastness with 93.3% strength retention. The experimental results demonstrate that the Nernst adsorption isotherm is a favourable model for polyimide fabric dyeing with disperse dyes.

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