Preparation of nano-SiO₂-IPBC microcapsule and its application in mildew resistance of Hevea brasiliensis

  Objective  This paper aims to prepare a new nano SiO₂-IPBC microcapsule fungicide and study its characteristics, as well as improve the fixation and aging resistance of 3-iodo-2-propynyl-butyl-carbamate (IPBC) in wood, and expand its application in the field of wood mildew proof.

  Method  Nano SiO₂-IPBC microcapsules were prepared by blending IPBC and nano SiO₂ particles in a vacuum, nano SiO₂ prepared by sol-gel method was the capsule wall, and IPBC was the capsule core. The microcapsules were characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), UV-aging resistance, and slow-release performance. Taking Hevea brasiliensis as the research object, Botryodiplodia theobromae, Aspergillus niger, Trichoderma viride, and Penicillium citrinum as the tested strains. The comprehensive indicators were obtained from different mass fraction microcapsule-ethanol impregnated rubber wood treatments.

  Result  Nano SiO₂-IPBC microcapsules were regular spherical, with particle size distribution between 20–100 nm and coating rate of 46.33%. The temperature of the weight loss of microcapsules was 120–280 ℃. Only slight yellowing occurred after 60-min UV aging; in 20% ethanol aqueous solution, the release rate of microcapsules was fast in the first 60 min, gradually slowed down in the next 180 min, and its release rate reached 50% in 240 min. FTIR analysis showed that there were Si−OH bonds in the microcapsules. SEM showed that microcapsules were not only distributed in wood vessels, but also deposited in wood pits. The results of mildew proof experiment showed that with the increase of the mass fraction of the microcapsule fungicide, the control effect against 4 fungi had gradually improved. When the mass fraction of microcapsule fungicide increased to 1.25%, the control effect against Botryodiplodia theobromae, Aspergillus niger, Trichoderma viride and Penicillium citrinum reached the highest level, which were 78.125%, 75.000%, 68.750% and 62.750%, respectively. The order of control effect (from strong to weak) was as follows: Botryodiplodia theobromae > Penicillium citrinum > Trichoderma viride > Aspergillus niger.

  Conclusion  The nano SiO₂-IPBC microcapsules prepared in this study improve the UV aging resistance of IPBC, as well as has a slow-release effect. The microcapsule fungicide has an excellent inhibitory effect on the 4 common mildews of rubber wood and has the best control effect on Botryodiplodia theobromae.