Development of a Route to Functional Polymers via Click Chemistry
Abstract
Functional polymers are desirable due to their use in applications such as drug delivery and bioimaging. This work describes the development of a functional polymer template, expanding upon current routes to creating functional polymer libraries. The methodology utilizes a masking-unmasking strategy to protect and then reveal a strained alkyne for the introduction of functional entities via post-polymerization modification.
The synthesis and characterization by high-resolution mass spectrometry as well as 1H NMR, UV-Vis, and FT-IR spectroscopy of a masked strained alkyne monomer is presented. First, the strained alkyne, masked by a cyclopropenone moiety, was synthesized. Next, a norbornene derivative was covalently attached to the masked strained alkyne to make a monomer capable of ring-opening polymerization and post-polymerization functionalization. The polymerization of masked monomer was then performed and characterized by 1H NMR, UV-Vis, and FT-IR spectroscopy which confirmed the retention of the cyclopropenone moiety. The unmasking of strained alkyne polymer via UV light irradiation and modification via strain-promoted azide-alkyne cycloaddition is also presented. The azides introduced included benzyl azide and a Au25 azide nanocluster. The benzyl functionalized polymer was characterized by 1H NMR, UV-Vis, and FT-IR spectroscopy. The Au25 functionalized polymer was characterized by UV-Vis, FT-IR, and X-ray photoelectron spectroscopy.
The amenability of this strategy to both small molecule and more complex azides is displayed. This provides an exciting new route towards post-polymerization modification to yield a library of functional polymers. This strategy also has the potential for applications in photopatterning as the unmasking method has spatiotemporal control.