INFORMED DESIGN OF POLYMER-SELECTIVE NANOPROBES FOR OPTICAL SUPER-RESOLUTION MICROSCOPY

Abstract

Polymer systems and nanocomposites thereof encompass an enormous array of materials with applications in virtually all aspects of life, from clothing and construction to drug delivery and optics. This versatility is largely due to their incredible range of compositions, architectures, and, by extension, properties and capabilities. The advancement of polymers in highly specialized and varied roles relies directly on scientific knowledge of the parameters governing their properties; that is, understanding polymer fundamentals translates to fine control over the preparation, behavior, and potential functions of these invaluable materials. Elucidating the principles that determine polymer interactions requires a multifaceted approach, combining traditional strategies with cutting-edge tools to strengthen and expand on such mechanistic insights. Conventionally, characterization of polymer systems has deferred to scanning probe– and electron-based techniques like atomic force microscopy (AFM) and transmission electron microscopy (TEM). While indispensable on their own, these investigative tools stand to benefit from a newer set of visualization techniques in the form of optical super-resolution microscopy (OSRM). Using various strategies to overcome the diffraction limit of light, OSRM facilitates optical imaging of nanoscale features, thereby enabling in situ and/or multidimensional exploration of organic materials noninvasively. As OSRM was developed in and for biology, with environments often inconducive to condensed-state systems, a number of challenges have hindered the rapid adaptation of OSRM to polymer science. At the forefront of these impediments is the preparation of ultrabright, photostable, and polymer-specific optical probes that can faithfully label even nonpolar nanostructures. This dissertation revolves around the synthesis, characterization, and application of optical nanoprobes enabling the use of use stochastic optical reconstruction microscopy (STORM) to image nanostructures of block copolymer (BCP) thin films as a model system to evaluate the feasibility and performance of such designer probes. By enhancing the properties of encapsulated fluorescent dyes, core–shell (alumino)silica(te) nanoparticles serve as excellent optical probe candidates for STORM. The unique compositions of both the core and the shell translate to superior photophysical activity and chemical tunability, respectively, as compared to their parent dyes. These studies take advantage of their tailorable surface chemistries to enable compatibilization with chemically dissimilar nanodomains in amphiphilic BCPs using both reactive click chemistry attachment and noncovalent association in the form of solution-based mixing. In conjunction with AFM and TEM, multicolor STORM imaging of these nanocomposite BCP thin films facilitates well-rounded characterization of a polymer system. In doing so, thorough investigation of these materials showcases the potential of OSRM as a powerful complementary nanocharacterization tool in polymer science.