Figure 3.

(a) Images illustrating different surface microstructures of NFES polystyrene (PS) fibres fabricated from (i) a PS-DMF solution system, and (ii) a PS-THF solution system. (b) Microstructures of PS fibres recaptured from Lu et al.’s FFES work¹⁸ (Adapted with permission from American Chemical Society. Copyright 2013). (c) Microstructures of PS fibres recaptured from Megelski et al.’s FFES work²⁰ (Adapted with permission from American Chemical Society. Copyright 2002). In (b and c), each microstructure is labelled with an identifier, and are classified into one of three categories: with black-coloured labels indicating a smooth fibre surface, red labels a porous/textured fibre surface, and yellow-coloured label a transition (boundary). (d) Mapping of the estimated A_w versus $\overline{P}$ associated with different PS fibre fabrication conditions. Square symbols indicate values derived from conditions associated with NFES in (a); circular symbols from the FFES of (b); and triangular symbols from FFES of (c). WCA = water contact angle. (Note: The dotted red-line indicates the transition condition of $A_w\approx \overline{P}$ . If we cross this line from to the left-hand-side to the right-hand-side, we will cross the water interaction area to no water interaction area).