Effect of hollow silica spheres on water vapor permeability of polyacrylate film
Hollow silica spheres with different hollow size and shell thickness were synthesized via template method using PS spheres as templates and characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction and Brunauer–Emmett–Teller analysis. Then the effects of hollow size, shell thickness and content of hollow silica spheres on water vapor permeability of polyacrylate films were investigated. The results showed that hollow silica spheres with smaller hollow size and thinner shell thickness were more conducive to the improvement of water vapor permeability of composite films because they provided more free volume for the composite film. But too small hollow size or too thin shell thickness is unfavorable for water vapor permeability. Also, with the increase of the content of hollow silica spheres, the water vapor permeability of the composite film first increased and then decreased. In short, the composite film containing 2.0 wt% hollow silica spheres with a hollow size of 150 nm and shell thickness of 10 nm showed the best water vapor permeability.