Objective As a broad-spectrum organic fungicide, the poor water solubility and photostability of iodopropynyl butylcarbamate (IPBC) limit its application. To improve the water solubility and photostability of IPBC, and broaden its application in the field of wood and bamboo mold prevention, a new type of IPBC/β-cyclodextrin compound fungicide has been developed.

Method Using β-cyclodextrin (β-CD) as the host and IPBC as the guest, IPBC/β-CD compound fungicide was prepared by coprecipitation method. Three factors including the molar ratio of host to guest, reaction temperature and reaction time were selected to explore the influence of different factors on inclusion reaction and optimize the preparation process through single factor experiments. The fungicide was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), light aging resistance analysis and other methods. The solubilization characteristics of IPBC/β-CD compound fungicide were tested by phase solubility method. The anti-fungal efficacy of IPBC/β-CD compound fungicides with different mass fractions was evaluated using four fungi, namely Aspergillus niger, Botryodiplodia theobromae, Penicillium citrinum and Trichoderma viride, to obtain their comprehensive fungicide performance index.

Result (1) The crystal structure and physical properties of IPBC/β-CD compound fungicide had changed. The compound fungicide had uniform distribution and regular four sided microstructure characteristics. Taking inclusion rate as test index, the optimal preparation conditions of compound fungicide were as follows: the molar ratio of β-CD to IPBC was 4∶1, the reaction temperature was 50 ℃, and the reaction time was 4 h. Under these conditions, the inclusion rate of IPBC in the compound fungicide could reach 52.02%. (2) The thermal degradation temperature of effective component IPBC in compound fungicide was increased from 120 to 220 ℃, and only slight yellowing occurred on the surface after 60 min of UV irradiation. When the concentration of β-CD was 0.01 mol/L, the water solubility of IPBC could be increased by 1.65 times. (3) As the increase of mass fraction of antifungal agent, its anti-fungal efficacy against four types of fungi gradually was improved. The compound fungicide with a mass fraction of 1.00% had the best anti-fungal performance. After 7 d of cultivation, the diameters of inhibition zones of Aspergillus niger, Botryodiplodia theobromae, Penicillium citrinum and Trichoderma viride were 25.47, 49.12, 52.45, and 39.93 mm, respectively.

Conclusion The IPBC/β-CD wood compound fungicide prepared in this study improves the water solubility and photothermal stability of IPBC, and shows good control efficacy against four common wood and bamboo fungi. This study can enhance the application stability of IPBC, and expand its application in the field of wood and bamboo mold prevention.