Characterization of the pre-polymer and polymer products was consistent with that previously reported. In particular, Materials 1-4 were all black and absorbed light in the 300-800 nm range (S9-S16). EDX analysis of cross-sections and surfaces also indicated that sulfur was distributed evenly throughout Materials 1-4 and the g-Fe2O3 particles were also distributed throughout Materials 2 and 4 (S9-S16). Young's modulus was measured for each material using nanoindentation, providing values of 0.93 ± 0.31 GPa for Material 1, 1.07 ± 0.27 GPa for Material 2, 1.25 ± 0.39 GPa Material 3, and 1.88 ± 0.471 GPa for Material 4. Given the deformations of the surface in these measurements are on the order of 10-20 nm, the presence of the g-Fe2O3 nanoparticles had a negligible effect on the Young's modulus. Roughness analysis was carried out on areas of 1 mm by 0.1 mm for Materials 1-4 using optical profilometry. Surface roughness parameters Ra and Rq for all materials range from 90 nm ± 5 nm to 124 ±1 nm, and 120 ± 8 nm to 141 ± 2 nm, respectively. These measurements indicate Materials 1-4 are relatively flat over their surface, which is important for imaging laser modifications with dimensions ranging from hundreds of nm to microns. Surface modification of Materials 1-4 using a 690 nm, 1.10 mW diode laser. During routine analysis of Material 1 by AFM, it was discovered that the laser used in this microscopy system could rapidly modify the surface of the poly(S-r-CPD) polymer. These modifications occurred immediately on exposure of Material 1 to the laser light, and the optical microscope on the instrument could be used to image the dots and lines generated when the laser light was manually moved across the surface. A video of this process is provided in the Supporting Information (Video S1). This was a surprising result given the low power of this laser-a mere 1.10 mW-and the general inertness of many common polymers to this laser light (S23-S24).