In a typical procedure 1.2 g of PVAc is added to the 10 mL DMF
solution and stirred for about 12 h at roomtemperature. This is followed
by the addition of 2 mL of acetic acid and 1 mL TiP. To this solution
required amount of urea (1, 3, 5% w/w compared to TiO2) was added
followed by stirring for about 12 h. The solution was taken in a 10mL
syringe with 27 G 1∕2 gauge needle. Flow rate was kept at 1 mL/h and
the distance between the electrodes (needle tip and the collector) was
maintained at 12 cm. The applied voltage was 30 kV and the humidity
level inside the electrospinning chamber was ~50%. The as-spun
material could be collected in the form of a free-standing membrane
and was annealed at 500 °C for 1 h with 5 °C/min ramp rate in air. The
continuous fibers break down into rice grain-shaped structures during
the sintering process. This unique nanostructures arise from the
continuous as-spun nanofibers because of the microscale phase
separation between TiO2 and PVAc, owing to the solubility difference
between the two, during the initial stages of the sintering proces