Bioinspired thymine functionalized polymeric systems: from synthesis to nano applications

Nature is an abundant source of elegant examples of synthesis of materials, and as in many other areas of science, polymer chemists have been drawing on bioinspiration to create sophisticated functional materials. Thymine, one of the nucleic bases in DNA, is well known for its ability to form relatively strong hydrogen bonds as well as its propensity to undergo reversible photo-dimerization upon UV exposure. The focus of this thesis is to develop a bioinspired thymine functionalized polymeric system based on hydrogen bonding and photo-crosslinking of thymine with potential nano applications such as in drug delivery and nanopatterned polymer films. In this research, thymine functionalized block copolymers were synthesized using controlled living radical polymerization. The block copolymers were used to prepare a stability enhanced core bound polymeric micelle system based on hydrogen bonding and photo-crosslinking of thymine. The stability of polymeric micelles was investigated in detail using various characterization techniques such UV-Vis spectroscopy, transmission electron microscopy, fluorescence spectroscopy and dynamic light scattering. Further to this, the chemical loading and release potential of polymeric micelles was investigated using suitable drugs (6-mercaptopurine and 6-thioguanine). The results demonstrated that hydrogen bonding of thymine plays an important role in the stability of micelles and can be exploited for chemical loading and release of encapsulated materials. Furthermore, it was found that photo-crosslinking can be used as a tool to tune the stability of polymeric micelles, and hence to control the release of encapsulated materials. The photo-crosslinking of thymine was also exploited to develop reversible polymers and crosslinked nanogels. Overall, these studies demonstrated the scope and versatility of incorporation of thymine in polymers in order to develop functional materials for various applications such as drug delivery systems, nanopatterned films, reversible polymers and nanogels.