Stable Organic Interfaces Having Unnatural Compositions: Nanoscale Control of Heterogeneity

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Professor T. Randall Lee of the University of Houston is supported by the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry to design and synthesize new organic chemical agents. A major goal of the proposed research is to tune the chemical composition of thin organic coatings to afford surfaces with compositions that are not found in nature. Given the unique compositions targeted, the coatings are likely to be extraordinarily non-adhesive and therefore useful for coating not only electronic devices (e.g., ultrathin cell phones, laptops, and flat-screen televisions), but also artificial implants (e.g., heart stents) and nanoparticles for medical applications (e.g., cancer therapy). During the grant period, the PI seeks to broaden the participation of women and minorities through several educational/outreach activities, including the Welch Summer Scholars program, the UH STEM Center, the NSF-supported Houston Louis Stokes Alliance for Minority Participation (H-LSAMP) program, and visits to campus and research mentoring for local high school students. The proposed research seeks to design, synthesize, and utilize multidentate adsorbates for the generation of unnatural "conflicted" self-assembled monolayers (SAMs) on gold. Three systems of current technological interest are emphasized: (1) the design and synthesis of multidentate adsorbates for fabricating highly stable thin-film coatings with uniquely controlled surface composition of chemical entities that are either phase incompatible or structurally dissimilar, for the purpose of generating homogeneously mixed heterogeneous "conflicted" interfaces; (2) the use of specifically fluorinated adsorbate molecules to generate nanoscale films having well-defined composition and structure, with an ultimate goal of defining the critical elements (e.g., minimum degree of fluorination) needed to construct organic interfaces with controlled hydrophobicity, anti-adhesiveness, and lubricity; and (3) the generation and study of thin-film architectures, including surface-grafted oligomeric films, in which the terminal functional groups mimic the backbones of industrially relevant polymers, with the goal of evaluating the interfacial properties and reactivity of well-defined polymer surfaces. Advantages offered by the targeted multidentate adsorbates include films with markedly greater stability than those derived from n-alkanethiols, leading in part to advances in nanoscale lubrication, corrosion resistance, nanoparticle stabilization, and anti-adhesive coatings. Furthermore, due to the restricted surface mobility of the multidentate adsorbates, mixed monolayers of these adsorbates functionalized with disparate chemical tailgroups offer "conflicted" organic nanoscale coatings with tailored chemical heterogeneity and controlled nanoscale roughness.