Electrospun nanofibers prepared by two methods: in situ emulsion polymerized PVA/nano TiO2 and mixing of functional-PVA with nano TiO2

Poly(vinyl alcohol)/nano-sized titanium dioxide (PVA/nanoTiO2) water dispersions were electrospun in order to prepare networks of polymer composite nanofiber for coating applications. In particular, the effect of the functionalization of the polymer matrix, coating of the filler particles, and the preparation method of the polymer dispersions on the nanoparticle distribution along the resulting fibers were studied. The dispersions were prepared using two different techniques: batch in situ emulsion polymerization and mixing methods. Differently coated hydrophilic nanoTiO2 particles were used on one hand, and on the other, pure PVA and carboxyl- and silanol-functionalized PVAs were used. Dispersion properties were assessed by measuring viscosity and estimating the degree of homogeneity before electrospinning. The structure of the electrospun fibers was studied using scanning electron microscopy and elemental analysis. It was observed that the dispersion properties differed substantially depending on the types of polymer and filler particles used. Electrospinning succeeded in forming continuous fibers instead of separate droplets with all except one type of PVA/nanoTiO2 dispersions. It was confirmed that the resulting fibers and droplets contained nanoTiO2 particles. For the in situ polymerized dispersions the filler distribution in the resulting fibers was strongly influenced by the nanoparticle coating. In the mixing method, the resulting nanoparticle distribution was affected primarily by the polymer type used, and the role of the nanoparticle coating was not important.