The highly water-soluble nematicide
fosthiazate is anticipated
to undergo microencapsulation in order to enhance its retention around
plant roots and mitigate leaching into groundwater. However, the underlying
mechanism governing the influence of hydrophilicity of the microcapsule
(MC) core on the evolution of the microcapsule shell remains unclear,
posing challenges for encapsulating water-soluble core materials.
This study elucidates the microlevel formation mechanism of microcapsules
by investigating the impact of interfacial mass transfer on shell
formation and proposes a method for regulating the structure of shells.
The study reveals that enhancing the hydrophilicity of the core enhances
the shuttle effect between the oil and aqueous phase, expands the
region of polymerization reactions, and forms a loose and thick shell.
The thickness of the microcapsule shell prepared using solvent oil
150# (MCs-SOL) measures only 264 nm, while that of the microcapsules
prepared using propylene glycol diacetate and solvent oil 150# at
a ratio of 2:1 (MCs-P2S1) is 5.2 times greater. The enhanced compactness
of the shell reduced the release rate of microcapsules and the leaching
distance of fosthiazate in soil, thereby mitigating the risk of leaching
loss and facilitating the distribution of active ingredients within
crop roots. The MCs-SOL had a limited leaching distance measurement
of 8 cm and exhibited a satisfactory efficacy of 87.3% in controlling
root galling nematodes. The thickness and compactness of the MCs shell
can be regulated by manipulating the interfacial shuttle effect, providing
a promising approach to enhancing utilization efficiency while mitigating
potential environmental risks.