Study Of The Fabrication Of Ordered Honeycomb Porous Polyvinyl Chloride(PVC) Films By Breath Figures Method

In the recent years,“Breath figures”(BFs) method for preparing highlyordered honeycomb porous films has attracted much attention for its potentialapplications in the fields of membrane separation, catalysis, optical technology andso on.In this study, ordered honeycomb-patterned polyvinyl chloride (PVC) porousfilms were first fabricated with hydrophilic tetrahydrofurane (THF) as solvent by BFsmethod. Given that the solubility of the PVC, three kinds of solvents were discussedrespectively. The results show that THF can still be a better choice for solventbecause of its strong volatility. Besides, several influencing parameters such aspolymer concentration, polymerization degree of PVC, surrounding air humidity wereillustrated respectively. The experimental results indicate that the increase ofsolution concentration leads to the decrease in the pore size of the resultant films,and even makes the porous structure disappear. However, the porous films can beeasily fabricated with higher polymerization degree of PVC at40mg·mL-1. Increasingair humidity is also advantageous to form well-ordered porous PVC films with largerpore size. With the RH58%, the porous structure can’t be gained because of the lesswater droplets. On the contrary, numerous small holes at the bottom of the filmmake the porous structure less ordered. Therefore, an appropriate relative humidityis vital to the film formation.Considering the hydrophily of THF, adding surfactant were supposed to preventthe coalescence of the water droplets so as to make the porous structure moreordered and the function of surfactant modification was also aimed to make a fullunderstanding of BFs. Firstly, the hydrophilic end of the surfactant can easily be combined with the water droplets, while the hydrophobic group can firmly fix thewater molecules in the casting solution, thus to a large extent, hindered the degreeof water coalescence. Different kinds of surfactant perform differently according tovarious functional group, making differences on the film morphology. Besides, theadditive amount of surfactant influences a lot on the regularity. The results show thatan appropriate amount of Polyvinyl Pyrrolidone (PVP) can decrease the hole size,however, an excess amount can make the structure more disordered because of thesystem chaos. The blend film of Poly Styrene(PS) and PVC were also illustrated towiden the application and preparation of honey-comb films.