Novel Thymine-Functionalized Polystyrenes for Applications in Biotechnology. Polymer Synthesis and Characterization

Abstract

Novel polystyrenes (PS) carrying thymine functional groups were synthesized by copolymerizing styrene (St) and 1-(vinylbenzyl)thymine (1-VBT) in the presence and absence of divinylbenzene (DVB) in batch free radical emulsion polymerization. Microsphere latexes were obtained with an average particle size of ≈60 nm (3.0 and 5.0 wt % [VBT]0) with ≈80% conversion and ≈38 nm (10 wt % [VBT]0) with 91% conversion. The final copolymer latexes were freeze-dried to obtain particles in the size range of 32−544 μm. Copolymer compositions were determined by FTIR-DRIFT, 1H NMR, and elemental analysis and were found to be close to the composition of the monomer charges. XPS analysis revealed that VBT concentration on the surface of the particles was much higher (17, 24, and 36 wt %) than in the bulk. Phenol was selected as a model compound to examine adsorption onto the thymine functional groups. Hydrogen bonding between the phenolic hydroxyl group and the thymine units of soluble polymers was evidenced by 1H NMR and FTIR spectroscopy. Adsorption isotherms obtained with all samples showed a good fit with Langmuir's model, supporting evidence for a monolayer chemisorption model in the heterogeneous adsorbent−phenol/hexane system investigated. 89.4% of the phenol was desorbed by adding Borax buffer solution of pH ≥ 10 to the adsorbent−phenol/hexane system. These novel copolymers have potential in biotechnology.