Single-step, contactless femtosecond laser micromachining of substrates to impart specific surface morphologies has been the focus of considerable recent work. This work has primarily focused on experimentation with metallic substrates, with fs-laser micromachining of polymeric materials being in its infancy. In the present work, we report on the fs-laser micromachining of urethane based, amorphous, non-block co-polymeric networks, where previously published literature has, to-date, solely discussed micromachining of homopolymeric substrates. The results of this work show that there exists regimes of micromachining where the imparted microstructure resembles those of selected irradiated homopolymers. Further inspection reveals the role of co-monomer added in determining the imparted microstructure through measurement of the material ionization threshold fluence, and incubation coefficient. Chemical and optical effects of co-monomer addition are also considered through XPS and UV-Vis spectroscopic analyses, respectively.