We present numerical simulations of solitary wave emission from a waveguide in which the cladding is the non-linear material polydiacetylene para-toluene sulfphonate (PTS). In addition to a self-focusing cubic non-linearity PTS exhibits a defocusing quintic non- linearity, which imposes a limit on the peak non-linear index change. The influence of this limiting on solitary wave emission is studied in detail in one transverse dimension, and we show that it can increase the fraction of the incident power transferred into the emitted solitary wave. Fabrication issues arising from the limiting are also discussed. Numerical simulations in two transverse dimensions are also presented showing stable emitted solitary waves due to the stabilizing effect of the limiting, in contrast to the self-focusing collapse which occurs for a cubic non-linearity.