503069.fig.001a
(a)
503069.fig.001b
(b)
503069.fig.001c
(c)
503069.fig.001d
(d)
Figure 1: Chemical structures of (a) ibuprofen (IBU), (b) poly(acrylic acid) (PAA), (c) poly(N-vinyl pyrrolidone) (PVP), and (d) poly(4-vinyl phenol) (PVPh).