Temporally Arrested Breath Figure in Presence of Solvents

Abstract

The purpose of this project is to study a new inexpensive and efficient technique of creating porous film from the breath figure (BF) approach and gaining an understanding of how the pores can be tuned to the desired size. The technique considers the approach of UV curing in the presence of a solvent when fabricating the porous film, thus a photocurable polymer was chosen to ensure that the polymer film is polymerised, and two solvents were used to experiment on the effects of what different chemical properties can do to the size and shape of the pores. The polymer used is the Norland Optical Adhesives NOA 63, and this stayed constant throughout the project; moreover, two solvents were used with different chemical properties: toluene, and acetone. Three sets of data was collected for NOA 63 (polymer only), NOA 63 with acetone and NOA 63 with toluene.

Two experiments were carried out to understand how different parameters affect the pore sizes and shape of the films, this was to have the knowledge on how to control these parameters and use that to tune the pores to the size and shape desired. The first experiment was to see how sensitive the pores were to temperature. This was conducted to a high and low temperature (−5 ± 1 °𝐶 and −12 ± 1 °𝐶, respectively) with a constant time of 𝑡 = 330 𝑠. It was detected that NOA 63 with acetone samples were most sensitive than the NOA 63 and NOA 63 with toluene. The second experiment was the transient analysis, this was to see how increase of time affected the pores. This was completed for 𝑡 = 150 𝑠 and 𝑡 = 330 𝑠, for all three cases under both temperature conditions; it was found that the longer the cooling duration the larger the pores.