wavelength and power. Encouraged by the intriguing results in the previous section, the next series of experiments was carried out on a laser system that could be varied in wavelength and power. Additionally, it was desirable to use a laser system that could be programmed to control the site and duration of laser exposure. For these purposes, a Horiba XplorRA confocal Raman microscope was used (S6-S7). This instrument was not used for Raman spectroscopy of Materials 1-4, but rather as a platform for controlled and automated exposure of the materials to varying wavelengths of laser light. The Horiba system contains 786 nm and 638 nm diode lasers, and a 532 nm Nd:YAG laser with a diode pump source. The power of the lasers could be modulated, and the movement of the microscope stage could be automated for precise control of the polymer modifications. Initial experiments on this system involved programming the stage to move in a line relative to the laser at speeds of 9, 18, and 74 µm/s (S25-S38). This setup enabled a line of laser light to be traced across the surface of Materials 1-4 with controlled exposure time. The aim was to establish which laser settings result in polymer modification and how that modification could be controlled in dimension and type (e.g. swelling vs ablation). Additionally, it was important to analyze the elemental composition at the site of the modification to gain some understanding of the chemical changes that may occur during exposure to the laser. For each speed, the laser power was varied using attenuators (1, 7, 10, 17.5, 25 and 50% of full power) across the three wavelengths (532, 638 and 786 nm). These preliminary tests indicated that the speed of laser movement across the surface of the polymer could impart some control over the width and depth of the resulting channel formed by ablation (S39-S44). However, the laser power had a greater impact on the resulting modification, as discussed below.