UBC Theses and Dissertations
Surface-initiated polymerization for the preparation of organic electronic materials Poisson, Jade
Polymer organic electronics are pervasive in materials chemistry and life sciences. These materials demonstrate mechanical properties ideal for solution processing and flexible electronic applications. The molecular weight and dispersity of a polymer can also have a profound effect on the properties of the material. Consequently, the use of controlled polymerization techniques is critical in the preparation of organic electronics. Herein, controlled polymerization techniques are used to prepare semiconducting materials demonstrating unique charge-transport and photophysical properties. Thermally activated delayed fluorescent (TADF) materials have been used widely in bioimaging, photocatalysis and organic light emitting diodes (OLEDs). TADF materials can, in theory, achieve full conversion of electricity to light making them particularly useful in OLEDs. However, many of these materials demonstrate low rates of reverse intersystem crossing process. These rates can improve when utilizing TADF materials demonstrating through space rather than through bond charge transfer. Thus, in this work a library of through-space charge transfer materials is explored. However, the charge transfer character of the emission in TADF materials results in broad emission bands. The colour purity can be improved by including an appropriate fluorophore to which the TADF moiety can transfer energy, termed thermally assisted fluorescence (TAF). Surface-initiated polymerization (SIP) is an approach to prepare densely grafted polymers on a surface. These “polymer brushes” often demonstrate properties that differ from “free” polymers. Thus, the incorporation of luminophores into polymer brushes could result in unique photophysical properties. Additionally, the use of SIP approaches enable optoelectronically relevant materials to be grown directly from substrates. However, polymer brushes containing TADF and TAF moieties have yet to be explored. Thus, in this work, controlled surface-initiated polymerization techniques are used to prepare polymer brushes incorporating TADF and TAF that show promise for use in lighting and spatially resolved sensing applications. Finally, these SIP approaches are leveraged to investigate unique polymer brush architectures known as bottlebrush brushes. These materials enable high surface coverage of the polymer coating on a substrate while still allowing mass transport of molecules through the brushes affording a molecular wire-type structure. This architecture shows promise as a polyelectrolyte material.
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