Mass Spectrometry and Fluorescence Investigations of Physisorbed Self Assembled Monolayer Polymerization

Wilczek, Luke

Full Metadata

Overview

Year:: 2022
Contributor:: Wilczek, Luke (creator); Zimmt, Matthew (Advisor); Basu, Amit (Reader); Robinson, Jerome (Reader); Brown University. Department of Chemistry (sponsor)
Genre:: theses
Subject:: Fluorescence; Mass spectrometry; Polymerization; Scanning tunneling microscopy; monolayer
Extent:: xviii, 220 p.

Files

Description

Abstract:: Physisorbed, multi-component self-assembled monolayers (SAMs) that exhibit designed patterns of molecules on graphite surface have garnished attention in recent years. In principle, spatial arrangements of functional groups in patterned monolayers (ML) can be leveraged to build patterned 3-D structures. Unfortunately, physisorbed MLs are highly susceptible to desorption upon exposure to common organic solvents including acetone, THF, DCM, toluene and others. Post assembly polymerization of SAMs is sometimes used to increase ML durability. Most reported polymerization approaches react functional groups that also play a role in determining ML morphology. Structural changes required for reaction can limit the extent of polymerization or disrupt the ML morphology. This thesis investigates a novel molecular design for ML polymerization at the solution – HOPG interface: each assembled triphenylethynylene (TPE) molecule in the ML extends two chains into solution that can react without altering ML packing interactions. The goals of polymerizing the solution assessable portions of these SAMs are to incorporate every physisorbed molecule into polymer, to greatly enhance ML adhesion to graphite (HOPG), and to expand the number of post-assembly applications of physisorbed, patterned ML systems. Two novel mass spectroscopy methodologies are used to characterize the formation and properties of the polymerized monolayers (p-ML). MALDI FTICR mass spec is used to track ML polymerization kinetics induced by Glaser-Hay reaction of physisorbed TPE molecules bearing two, short terminal alkyne, linker chains. LDI TOF mass spec is used as part of a vacancy assay to quantify the amount of ‘bare’ HOPG surface produced when solvent challenges desorb TPE polymers from the HOPG. A complementary fluorescence method is used to quantify the number of p-ML TPE units desorbed by the solvent challenge, taking advantage of TPEs’ strong solution luminescence. The effects of TPE linker length on p-ML formation kinetics and p-ML durability are assessed. The results demonstrate that these TPE MLs undergo a diffusionless step-growth polymerization and that polymerization dramatically increases the durability of physisorbed monolayer exposure to common organic solvents.
Notes:: Thesis (Ph. D.)--Brown University, 2022

Content

Citation

Wilczek, Luke, "Mass Spectrometry and Fluorescence Investigations of Physisorbed Self Assembled Monolayer Polymerization" (2022). Chemistry Theses and Dissertations. Brown Digital Repository. Brown University Library. https://repository.library.brown.edu/studio/item/bdr:xfey75ww/

Relations

Collection:

Chemistry Theses and Dissertations

Theses and Dissertations for the Chemistry department.
...