<br/>Efficient, long-range transport of excitons (electron-hole pairs) is an ongoing and non-facile challenge in the design of molecular materials. We are developing a new approach to the design of molecular photonic materials that combines biologically inspired design principles with the exciting new physics of strong light-matter coupling. The functionalisation of polymer brushes grown from gold nanostructure arrays with pigments provides three-dimensional organisation of excitons at interfaces – an essential requirement for long-range exciton transport. We have shown that numerous factors impact the post-polymerisation functionalization of water-soluble aldehyde-functional polymer brushes (PAGEO5MA). Surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) was employed to synthesise PAGEO5MA brushes at various grafting densities. The grafting density was varied by diluting the coverage of initiator on the surface. PAGEO5MA brushes underwent reductive amination with dyes of various molecular weights. UV/vis spectroscopy allowed for qualitative detection of the dyes while XPS studies were used to determine the number of dye-functionalised segments. Increasing the size of the dye reduced the extent of dye incorporation within the brush, attributed to steric exclusion of the larger dyes. However, the extent of dye incorporation could be regulated by the grafting density, with more diffuse brushes allowing greater dye incorporation. Poorer polymer solvents collapsed the PAGEO5MA brushes, resulting in a reduction in dye functionalised segments. Understanding how to regulate post-polymerisation functionalization of brushes is essential for controlling the 3D organisation of pigments at interfaces.<br/><br/>Figure 1. Schematics showing the design principle for dye functionalised polymer brushes. Reducing the grafting density increased the extent of dye incorporation but reduced the amount of polymer material at the interface.

Polymer brush scaffolds for the immobilization of pigments at interfaces: Interrogating the factors which influence post-polymerization functionalization

ACS Spring 2022

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