Bioinspired water-soluble thymine based polymers

Jennifer Raudys and John Warner, Department of Chemistry, University of Massachusetts/Boston

100 Morrissey Blvd, Boston MA 02125, USA

Tel: 617-287-6515, Fax: 617-287-6127, E-mail: jraudys@hotmail.com

A benign control-release mechanism was developed using bioinspired water-soluble thymine based polymers co-polymerized with quaternary ammonium salts. It was shown that UV exposure induced photo-dimerization between the thymine molecules in the polymer. It was also demonstrated that the photodimerization increased proportionally to increased UV exposure.

Vinyl benzyl Thymine when copolymerized with a quaternary ammonium salt is water-soluble. When this polymer is exposed to 254nm UV light a 2p + 2p photodimerization takes place between the thymine molecules and renders the polymer water insoluble.

The amount of exposure to the UV light is proportional to the amount of 2p + 2p photodimerization that takes place.

The control – release mechanism was developed by utilizing the thymine cross link phenomena and the fact that the polymer can be polymerized in different monomer ratios. It was demonstrated that the thymine cross links could trap a molecule into the polymer by its water insoluble crosslink matrix and that the size of the cross link matrix can be controlled by changing the monomer ratios from 1:1 up to 1:32.

It was also demonstrated that the amount of the molecule trapped in the matrix could be controlled by the length of time that the polymer was exposed to the UV light. To increase the amount of molecules trapped in the polymer, the exposure to UV light must be increased.

Experiments were performed where a substance and the polymer were coated onto a film and exposed to UV light for different time intervals. The films were then immersed into water and measured by a UV-VIS spectrophotometer to determine the amount of substance that diffused out of the polymer matrix. It was demonstrated that the amount of diffusion decreased with longer exposure times.

The design of this polymer control – release system is environmentally benign in that it is water soluble, energy efficient, and reusable. It also eliminates the common problem of monomer leakage into the environment that is common to many organic polymers.