Due to their opto-electronic properties, two-dimensional gold nanoparticle arrays are being explored for various applications, such as sensing and catalysis. In particular, many of these applications take advantage of the nanoparticles' localized surface plasmon resonances, in which the conduction electrons on the surfaces of the gold nanoparticles in a 2D array oscillate at a well-defined frequency when excited by light that is resonant with this frequency. This excitation of the LSPRs results in the absorption of light at a specific wavelength and the generation of an intense electric field near the surface of the nanoparticle array. The frequency of the LSPR in a 2D gold nanoparticle array is greatly affected by the extent to which the LSPRs of neighboring nanoparticles can couple, and thus how the nanoparticles are specifically arranged in the array. In order for gold nanoparticle arrays to be successfully used in applications dependent on this opto-electronic property, it is critical to fabricate arrays in which the exact 2D patterning of the nanoparticles can be carefully controlled. Traditionally, the synthesis of highly ordered 2D gold nanoparticle arrays is often either expensive (if done through lithography) or uncontrollable (if done through self-assembly). This study explores a new strategy to mitigate these issues by using peptoid nanosheets as platforms to organize dodecanethiol functionalized gold nanoparticles into ordered arrays. These nanosheets form through a unique film collapse mechanism at the toluene-water interface. UV-vis spectra of nanosheets prepared with different nanoparticle concentrations were obtained, showing that the optical properties of the sheets can be tuned by altering their synthesis parameters. The sheets were characterized using light microscopy, scanning electron microscopy, and atomic force microscopy to determine how the structure and morphology of these sheets is affected by the concentration of gold nanoparticles. Based on their tunable optical properties, these new composite materials are promising candidates for applications like sensing and catalysis.